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    From DOE’s Thomas Jefferson National Accelerator Facility (US): “Electrons Set the Stage for Neutrino Experiments” 

    From DOE’s Thomas Jefferson National Accelerator Facility (US)

    1

    Early-career nuclear physicists show that a better understanding of how neutrinos interact with matter is needed to make the most of upcoming experiments.

    Neutrinos may be the key to finally solving a mystery of the origins of our matter-dominated universe, and preparations for two major, billion-dollar experiments are underway to reveal the particles’ secrets. Now, a team of nuclear physicists have turned to the humble electron to provide insight for how these experiments can better prepare to capture critical information. Their research, which was carried out at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility and recently published in Nature, reveals that major updates to neutrino models are needed for the experiments to achieve high-precision results.

    Neutrinos are ubiquitous, generated in copious numbers by stars throughout our universe. Though prevalent, these shy particles rarely interact with matter, making them very difficult to study.

    “There is this phenomenon of neutrinos changing from one type to another, and this phenomenon is called neutrino oscillation. It’s interesting to study this phenomenon, because it is not well understood,” said Mariana Khachatryan, a co-lead author on the study who was a graduate student at Old Dominion University (US) in Professor and Eminent Scholar Larry Weinstein’s research group when she contributed to the research. She is now a postdoctoral research associate at The Florida International University (US).

    One way to study neutrino oscillation is to build gigantic, ultra-sensitive detectors to measure neutrinos deep underground. The detectors typically contain dense materials with large nuclei, so neutrinos are more likely to interact with them. Such interactions trigger a cascade of other particles that are recorded by the detectors. Physicists can use that data to tease out information about the neutrinos.

    “The way that neutrino physicists are doing that is by measuring all particles coming out of the interaction of neutrinos with nuclei and reconstructing the incoming neutrino energy to learn more about the neutrino, its oscillations, and to measure them very, very precisely,” explained Adi Ashkenazi. Ashkenazi is the study’s contact author who worked on this project as a research scholar in Professor Or Hen’s research group at The Massachusetts Institute of Technology (US). She is now a senior lecturer at Tel Aviv University [ אוּנִיבֶרְסִיטַת תֵּל אָבִיב ](IL).

    “The detectors are made of heavy nuclei, and the interactions of neutrinos with these nuclei are actually very complicated interactions,” Ashkenazi said. “Those neutrino energy reconstruction methods are still very challenging, and it is our work to improve the models we use to describe them.”

    These methods include modeling the interactions with a theoretical simulation called GENIE, allowing physicists to infer the energies of the incoming neutrinos. GENIE is an amalgam of many models that each help physicists reproduce certain aspects of interactions between neutrinos and nuclei. Since so little is known about neutrinos, it’s difficult to directly test GENIE to ensure it will produce both accurate and high-precision results from the new data that will be provided by future neutrino experiments, such as the Deep Underground Neutrino Experiment (DUNE) or Hyper-Kamiokande.

    FNAL DUNE LBNF (US) from FNAL to Sanford Underground Research Facility, Lead, South Dakota, USA.

    FNAL DUNE LBNF (US) Caverns at Sanford Underground Research Facility.

    Hyper-Kamiokande [(神岡宇宙素粒子研究施設](JP) a neutrino physics laboratory to be located underground in the Mozumi Mine of the Kamioka Mining and Smelting Co. near the Kamioka section of the city of Hida in Gifu Prefecture, Japan.

    To test GENIE, the team turned to a humble particle that nuclear physicists know a lot more about: the electron.

    “This exploits the similarities between electrons and neutrinos. We are using electron studies to validate neutrino-nucleus interaction models,” said Khachatryan.

    Neutrinos and electrons have many things in common. They both belong to the subatomic particle family called leptons, so they are both elementary particles that aren’t affected by the strong force.

    In this study, the team used an electron-scattering version of GENIE, dubbed e-GENIE, to test the same incoming energy reconstruction algorithms that neutrino researchers will use. Instead of using neutrinos, they used recent electron results.

    “Electrons have been studied for years, and the beams of the electrons have very precise energies,” said Ashkenazi. “We know their energies. And when we are trying to reconstruct that incoming energy, we can compare that to what we know. We can test how well our methods work for various energies, which is something you can’t do with neutrinos.”

    The input data for the study came from experiments conducted with the CLAS detector at Jefferson Lab’s Continuous Electron Beam Accelerator Facility [below], a DOE user facility. CEBAF is the world’s most advanced electron accelerator for probing the nature of matter. The team used data that directly mirrored the simplest case to be studied in neutrino experiments: interactions that produced an electron and a proton (vs. a muon and a proton) from nuclei of helium, carbon and iron. These nuclei are similar to materials used in neutrino experiment detectors.

    Further, the group worked to ensure that the electron version of GENIE was as parallel as possible to the neutrino version.

    “We used the exact same simulation as used by neutrino experiments, and we used the same corrections,” explained Afroditi Papadopoulou, co-lead author on the study and a graduate student at MIT who is also in Hen’s research group. “If the model doesn’t work for electrons, where we are talking about the most simplified case, it will never work for neutrinos.”

    Even in this simplest case, accurate modeling is crucial, because raw data from electron-nucleus interactions typically reconstruct to the correct incoming electron beam energy less than half the time. A good model can account for this effect and correct the data.

    However, when GENIE was used to model these data events, it performed even worse.

    “This can bias the neutrino oscillation results. Our simulations must be able to reproduce our electron data with its known beam energies before we can trust they will be accurate in neutrino experiments,” said Papadopoulou.

    Khachatryan agreed.

    “The result is actually to point out that there are aspects of these energy reconstruction methods and models that need to be improved,” said Khachatryan. “It also shows a pathway to achieve this for future experiments.”

    The next step for this research is to test specific target nuclei of interest to neutrino researchers and at a broader spectrum of incoming electron energies. Having these specific results for direct comparison will assist neutrino researchers in fine-tuning their models.

    According to the study team, the aim is to achieve broad agreement between data and models, which will help ensure DUNE and Hyper-Kamiokande can achieve their expected high-precision results.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    JLab campus
    DOE’s Thomas Jefferson National Accelerator Facility (US) is supported by the Office of Science of the U.S. Department of Energy. DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, visit science.energy.gov.

    Jefferson Science Associates, LLC, a joint venture of the Southeastern Universities Research Association, Inc. and PAE Applied Technologies, manages and operates the Thomas Jefferson National Accelerator Facility for the U.S. Department of Energy’s Office of Science.

    History

    DOE’s Thomas Jefferson National Accelerator Facility(US) was established in 1984 (first initial funding by DOE, Department of Energy) as the Continuous Electron Beam Accelerator Facility (CEBAF); the name was changed to Thomas Jefferson National Accelerator Facility in 1996. The full funding for construction was appropriated by US Congress in 1986 and on February 13, 1987, the construction of the main component, the CEBAF accelerator begun. First beam was delivered to experimental area on 1 July 1994. The design energy of 4 GeV for the beam was achieved during the year 1995. The laboratory dedication took place 24 May 1996 (at this event the name was also changed). Full initial operations with all three initial experiment areas online at the design energy was achieved on June 19, 1998. On August 6, 2000 the CEBAF reached “enhanced design energy” of 6 GeV. In 2001, plans for an energy upgrade to 12 GeV electron beam and plans to construct a fourth experimental hall area started. The plans progressed through various DOE Critical Decision-stages in the 2000s decade, with the final DOE acceptance in 2008 and the construction on the 12 GeV upgrade beginning in 2009. May 18, 2012 the original 6 GeV CEBAF accelerator shut down for the replacement of the accelerator components for the 12 GeV upgrade. 178 experiments were completed with the original CEBAF.

    In addition to the accelerator, the laboratory has housed and continues to house a free electron laser (FEL) instrument. The construction of the FEL started 11 June 1996. It achieved first light on June 17, 1998. Since then, the FEL has been upgraded numerous times, increasing its power and capabilities substantially.

    Jefferson Lab was also involved in the construction of the Spallation Neutron Source (SNS) at DOE’s Oak Ridge National Laboratory (US). Jefferson built the SNS superconducting accelerator and helium refrigeration system. The accelerator components were designed and produced 2000–2005.

    Accelerator

    The laboratory’s main research facility is the CEBAF accelerator, which consists of a polarized electron source and injector and a pair of superconducting RF linear accelerators that are 7/8-mile (1400 m) in length and connected to each other by two arc sections that contain steering magnets.

    As the electron beam makes up to five successive orbits, its energy is increased up to a maximum of 6 GeV (the original CEBAF machine worked first in 1995 at the design energy of 4 GeV before reaching “enhanced design energy” of 6 GeV in 2000; since then the facility has been upgraded into 12 GeV energy). This leads to a design that appears similar to a racetrack when compared to the classical ring-shaped accelerators found at sites such as European Organization for Nuclear Research [Organisation européenne pour la recherche nucléaire](CH) or DOE’s Fermi National Accelerator Laboratory(US). Effectively, CEBAF is a linear accelerator, similar to DOE’s SLAC National Accelerator Laboratory (US) at Stanford University (US), that has been folded up to a tenth of its normal length.

    The design of CEBAF allows the electron beam to be continuous rather than the pulsed beam typical of ring shaped accelerators. (There is some beam structure, but the pulses are very much shorter and closer together.) The electron beam is directed onto three potential targets (see below). One of the distinguishing features of Jefferson Lab is the continuous nature of the electron beam, with a bunch length of less than 1 picosecond. Another is Jefferson Lab’s use of superconducting Radio Frequency (SRF) technology, which uses liquid helium to cool niobium to approximately 4 K (−452.5 °F), removing electrical resistance and allowing the most efficient transfer of energy to an electron. To achieve this, Jefferson Lab houses the world’s largest liquid helium refrigerator, and it was one of the first large-scale implementations of SRF technology. The accelerator is built 8 meters below the Earth’s surface, or approximately 25 feet, and the walls of the accelerator tunnels are 2 feet thick.

    The beam ends in four experimental halls, labelled Hall A, Hall B, Hall C, and Hall D. Each hall contains specialized spectrometers to record the products of collisions between the electron beam or with real photons and a stationary target. This allows physicists to study the structure of the atomic nucleus, specifically the interaction of the quarks that make up protons and neutrons of the nucleus.

    With each revolution around the accelerator, the beam passes through each of the two LINAC accelerators, but through a different set of bending magnets in semi-circular arcs at the ends of the linacs. The electrons make up to five passes through the linear accelerators.

    When a nucleus in the target is hit by an electron from the beam, an “interaction”, or “event”, occurs, scattering particles into the hall. Each hall contains an array of particle detectors that track the physical properties of the particles produced by the event. The detectors generate electrical pulses that are converted into digital values by analog-to-digital converters (ADCs), time to digital converters (TDCs) and pulse counters (scalers).

    This digital data is gathered and stored so that the physicist can later analyze the data and reconstruct the physics that occurred. The system of electronics and computers that perform this task is called a data acquisition system.

    12 GeV upgrade

    As of June 2010, construction began on a $338 million upgrade to add an end station, Hall D, on the opposite end of the accelerator from the other three halls, as well as to double beam energy to 12 GeV. Concurrently, an addition to the Test Lab, (where the SRF cavities used in CEBAF and other accelerators used worldwide are manufactured) was constructed.

    As of May 2014, the upgrade achieved a new record for beam energy, at 10.5 GeV, delivering beam to Hall D.

    As of December 2016, the CEBAF accelerator delivered full-energy electrons as part of commissioning activities for the ongoing 12 GeV Upgrade project. Operators of the Continuous Electron Beam Accelerator Facility delivered the first batch of 12 GeV electrons (12.065 Giga electron Volts) to its newest experimental hall complex, Hall D.

    In September 2017, the official notification from the DOE of the formal approval of the 12 GeV upgrade project completion and start of operations was issued. By spring 2018, all fours research areas were successfully receiving beam and performing experiments. On 2 May 2018 the CEBAF 12 GeV Upgrade Dedication Ceremony took place.

    As of December 2018, the CEBAF accelerator delivered electron beams to all four experimental halls simultaneously for physics-quality production running.

     
  • richardmitnick 2:52 pm on November 24, 2021 Permalink | Reply
    Tags: , , CEBAF: Jefferson Lab’s Continuous Electron Beam Accelerator Facility., DOE's Thomas Jefferson National Accelerator Facility (US), , GENIE is an amalgam of many models that each help physicists reproduce certain aspects of interactions between neutrinos and nuclei., Hyper-Kamiokande [(神岡宇宙素粒子研究施設](JP), Modeling the interactions with a theoretical simulation called GENIE, , , , The group worked to ensure that the electron version of GENIE was as parallel as possible to the neutrino version., The team used an electron-scattering version of GENIE dubbed e-GENIE to test the same incoming energy reconstruction algorithms that neutrino researchers will use., To test GENIE the team turned to a humble particle that nuclear physicists know a lot more about: the electron., When GENIE was used to model these data events it performed even worse.   

    From DOE’s Thomas Jefferson National Accelerator Facility (US): “Electrons Set the Stage for Neutrino Experiments” 

    From DOE’s Thomas Jefferson National Accelerator Facility (US)

    11/24/2021
    Kandice Carter
    Jefferson Lab Communications Office
    kcarter@jlab.org

    1

    Neutrinos may be the key to finally solving a mystery of the origins of our matter-dominated universe, and preparations for two major, billion-dollar experiments are underway to reveal the particles’ secrets. Now, a team of nuclear physicists have turned to the humble electron to provide insight for how these experiments can better prepare to capture critical information. Their research, which was carried out at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility and recently published in Nature, reveals that major updates to neutrino models are needed for the experiments to achieve high-precision results.

    Neutrinos are ubiquitous, generated in copious numbers by stars throughout our universe. Though prevalent, these shy particles rarely interact with matter, making them very difficult to study.

    “There is this phenomenon of neutrinos changing from one type to another, and this phenomenon is called neutrino oscillation. It’s interesting to study this phenomenon, because it is not well understood,” said Mariana Khachatryan, a co-lead author on the study who was a graduate student at Old Dominion University (US) in Professor and Eminent Scholar Larry Weinstein’s research group when she contributed to the research. She is now a postdoctoral research associate at Florida International University (US).

    One way to study neutrino oscillation is to build gigantic, ultra-sensitive detectors to measure neutrinos deep underground. The detectors typically contain dense materials with large nuclei, so neutrinos are more likely to interact with them. Such interactions trigger a cascade of other particles that are recorded by the detectors. Physicists can use that data to tease out information about the neutrinos.

    “The way that neutrino physicists are doing that is by measuring all particles coming out of the interaction of neutrinos with nuclei and reconstructing the incoming neutrino energy to learn more about the neutrino, its oscillations, and to measure them very, very precisely,” explained Adi Ashkenazi. Ashkenazi is the study’s contact author who worked on this project as a research scholar in Professor Or Hen’s research group at The Massachusetts Institute of Technology (US). She is now a senior lecturer at Tel Aviv University [ אוּנִיבֶרְסִיטַת תֵּל אָבִיב ](IL).

    “The detectors are made of heavy nuclei, and the interactions of neutrinos with these nuclei are actually very complicated interactions,” Ashkenazi said. “Those neutrino energy reconstruction methods are still very challenging, and it is our work to improve the models we use to describe them.”

    These methods include modeling the interactions with a theoretical simulation called GENIE, allowing physicists to infer the energies of the incoming neutrinos. GENIE is an amalgam of many models that each help physicists reproduce certain aspects of interactions between neutrinos and nuclei. Since so little is known about neutrinos, it’s difficult to directly test GENIE to ensure it will produce both accurate and high-precision results from the new data that will be provided by future neutrino experiments, such as the Deep Underground Neutrino Experiment (DUNE) or Hyper-Kamiokande.

    FNAL DUNE LBNF (US) from FNAL to Sanford Underground Research Facility, Lead, South Dakota, USA.
    FNAL DUNE LBNF (US) Caverns at Sanford Underground Research Facility.

    Hyper-Kamiokande [(神岡宇宙素粒子研究施設](JP) a neutrino physics laboratory to be located underground in the Mozumi Mine of the Kamioka Mining and Smelting Co. near the Kamioka section of the city of Hida in Gifu Prefecture, Japan.

    To test GENIE the team turned to a humble particle that nuclear physicists know a lot more about: the electron.

    “This exploits the similarities between electrons and neutrinos. We are using electron studies to validate neutrino-nucleus interaction models,” said Khachatryan.

    Neutrinos and electrons have many things in common. They both belong to the subatomic particle family called leptons, so they are both elementary particles that aren’t affected by the strong force.

    Standard Model of Particle Physics, Quantum Diaries

    In this study, the team used an electron-scattering version of GENIE dubbed e-GENIE to test the same incoming energy reconstruction algorithms that neutrino researchers will use. Instead of using neutrinos, they used recent electron results.

    “Electrons have been studied for years, and the beams of the electrons have very precise energies,” said Ashkenazi. “We know their energies. And when we are trying to reconstruct that incoming energy, we can compare that to what we know. We can test how well our methods work for various energies, which is something you can’t do with neutrinos.”

    The input data for the study came from experiments conducted with the CLAS detector at Jefferson Lab’s Continuous Electron Beam Accelerator Facility, a DOE user facility.

    Jlab CEBAF Large Accelerator Spectrometer.

    CEBAF is the world’s most advanced electron accelerator for probing the nature of matter. The team used data that directly mirrored the simplest case to be studied in neutrino experiments: interactions that produced an electron and a proton (vs. a muon and a proton) from nuclei of helium, carbon and iron. These nuclei are similar to materials used in neutrino experiment detectors.

    Further, the group worked to ensure that the electron version of GENIE was as parallel as possible to the neutrino version.

    “We used the exact same simulation as used by neutrino experiments, and we used the same corrections,” explained Afroditi Papadopoulou, co-lead author on the study and a graduate student at The Massachusetts Institute of Technology (US) who is also in Hen’s research group. “If the model doesn’t work for electrons, where we are talking about the most simplified case, it will never work for neutrinos.”

    Even in this simplest case, accurate modeling is crucial, because raw data from electron-nucleus interactions typically reconstruct to the correct incoming electron beam energy less than half the time. A good model can account for this effect and correct the data.

    However, when GENIE was used to model these data events it performed even worse.

    “This can bias the neutrino oscillation results. Our simulations must be able to reproduce our electron data with its known beam energies before we can trust they will be accurate in neutrino experiments,” said Papadopoulou.

    Khachatryan agreed.

    “The result is actually to point out that there are aspects of these energy reconstruction methods and models that need to be improved,” said Khachatryan. “It also shows a pathway to achieve this for future experiments.”

    The next step for this research is to test specific target nuclei of interest to neutrino researchers and at a broader spectrum of incoming electron energies. Having these specific results for direct comparison will assist neutrino researchers in fine-tuning their models.

    According to the study team, the aim is to achieve broad agreement between data and models, which will help ensure DUNE and Hyper-Kamiokande can achieve their expected high-precision results.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    JLab campus
    DOE’s Thomas Jefferson National Accelerator Facility (US) is supported by the Office of Science of the U.S. Department of Energy. DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, visit science.energy.gov.

    Jefferson Science Associates, LLC, a joint venture of the Southeastern Universities Research Association, Inc. and PAE Applied Technologies, manages and operates the Thomas Jefferson National Accelerator Facility for the U.S. Department of Energy’s Office of Science.

    History

    DOE’s Thomas Jefferson National Accelerator Facility(US) was established in 1984 (first initial funding by DOE, Department of Energy) as the Continuous Electron Beam Accelerator Facility (CEBAF); the name was changed to Thomas Jefferson National Accelerator Facility in 1996. The full funding for construction was appropriated by US Congress in 1986 and on February 13, 1987, the construction of the main component, the CEBAF accelerator begun. First beam was delivered to experimental area on 1 July 1994. The design energy of 4 GeV for the beam was achieved during the year 1995. The laboratory dedication took place 24 May 1996 (at this event the name was also changed). Full initial operations with all three initial experiment areas online at the design energy was achieved on June 19, 1998. On August 6, 2000 the CEBAF reached “enhanced design energy” of 6 GeV. In 2001, plans for an energy upgrade to 12 GeV electron beam and plans to construct a fourth experimental hall area started. The plans progressed through various DOE Critical Decision-stages in the 2000s decade, with the final DOE acceptance in 2008 and the construction on the 12 GeV upgrade beginning in 2009. May 18, 2012 the original 6 GeV CEBAF accelerator shut down for the replacement of the accelerator components for the 12 GeV upgrade. 178 experiments were completed with the original CEBAF.

    In addition to the accelerator, the laboratory has housed and continues to house a free electron laser (FEL) instrument. The construction of the FEL started 11 June 1996. It achieved first light on June 17, 1998. Since then, the FEL has been upgraded numerous times, increasing its power and capabilities substantially.

    Jefferson Lab was also involved in the construction of the Spallation Neutron Source (SNS) at DOE’s Oak Ridge National Laboratory (US). Jefferson built the SNS superconducting accelerator and helium refrigeration system. The accelerator components were designed and produced 2000–2005.

    Accelerator

    The laboratory’s main research facility is the CEBAF accelerator, which consists of a polarized electron source and injector and a pair of superconducting RF linear accelerators that are 7/8-mile (1400 m) in length and connected to each other by two arc sections that contain steering magnets.

    As the electron beam makes up to five successive orbits, its energy is increased up to a maximum of 6 GeV (the original CEBAF machine worked first in 1995 at the design energy of 4 GeV before reaching “enhanced design energy” of 6 GeV in 2000; since then the facility has been upgraded into 12 GeV energy). This leads to a design that appears similar to a racetrack when compared to the classical ring-shaped accelerators found at sites such as European Organization for Nuclear Research [Organisation européenne pour la recherche nucléaire](CH) or DOE’s Fermi National Accelerator Laboratory(US). Effectively, CEBAF is a linear accelerator, similar to DOE’s SLAC National Accelerator Laboratory (US) at Stanford University (US), that has been folded up to a tenth of its normal length.

    The design of CEBAF allows the electron beam to be continuous rather than the pulsed beam typical of ring shaped accelerators. (There is some beam structure, but the pulses are very much shorter and closer together.) The electron beam is directed onto three potential targets (see below). One of the distinguishing features of Jefferson Lab is the continuous nature of the electron beam, with a bunch length of less than 1 picosecond. Another is Jefferson Lab’s use of superconducting Radio Frequency (SRF) technology, which uses liquid helium to cool niobium to approximately 4 K (−452.5 °F), removing electrical resistance and allowing the most efficient transfer of energy to an electron. To achieve this, Jefferson Lab houses the world’s largest liquid helium refrigerator, and it was one of the first large-scale implementations of SRF technology. The accelerator is built 8 meters below the Earth’s surface, or approximately 25 feet, and the walls of the accelerator tunnels are 2 feet thick.

    The beam ends in four experimental halls, labelled Hall A, Hall B, Hall C, and Hall D. Each hall contains specialized spectrometers to record the products of collisions between the electron beam or with real photons and a stationary target. This allows physicists to study the structure of the atomic nucleus, specifically the interaction of the quarks that make up protons and neutrons of the nucleus.

    With each revolution around the accelerator, the beam passes through each of the two LINAC accelerators, but through a different set of bending magnets in semi-circular arcs at the ends of the linacs. The electrons make up to five passes through the linear accelerators.

    When a nucleus in the target is hit by an electron from the beam, an “interaction”, or “event”, occurs, scattering particles into the hall. Each hall contains an array of particle detectors that track the physical properties of the particles produced by the event. The detectors generate electrical pulses that are converted into digital values by analog-to-digital converters (ADCs), time to digital converters (TDCs) and pulse counters (scalers).

    This digital data is gathered and stored so that the physicist can later analyze the data and reconstruct the physics that occurred. The system of electronics and computers that perform this task is called a data acquisition system.

    12 GeV upgrade

    As of June 2010, construction began on a $338 million upgrade to add an end station, Hall D, on the opposite end of the accelerator from the other three halls, as well as to double beam energy to 12 GeV. Concurrently, an addition to the Test Lab, (where the SRF cavities used in CEBAF and other accelerators used worldwide are manufactured) was constructed.

    As of May 2014, the upgrade achieved a new record for beam energy, at 10.5 GeV, delivering beam to Hall D.

    As of December 2016, the CEBAF accelerator delivered full-energy electrons as part of commissioning activities for the ongoing 12 GeV Upgrade project. Operators of the Continuous Electron Beam Accelerator Facility delivered the first batch of 12 GeV electrons (12.065 Giga electron Volts) to its newest experimental hall complex, Hall D.

    In September 2017, the official notification from the DOE of the formal approval of the 12 GeV upgrade project completion and start of operations was issued. By spring 2018, all fours research areas were successfully receiving beam and performing experiments. On 2 May 2018 the CEBAF 12 GeV Upgrade Dedication Ceremony took place.

    As of December 2018, the CEBAF accelerator delivered electron beams to all four experimental halls simultaneously for physics-quality production running.

     
  • richardmitnick 11:51 am on November 8, 2021 Permalink | Reply
    Tags: "Through the nuclear looking glass", A neutron star is born when a very large star becomes a supernova and explodes., , , Connecting the physics of the very small — nuclei — to the physics of the very large — neutron stars, DOE's Thomas Jefferson National Accelerator Facility (US), FRIB- Facility for Rare Isotope Beams, , National Superconducting Cyclotron Laboratory (US) at Michigan State University, Neutron stars are more massive than our sun yet they’re only about as big as Manhattan Island., , , Scientists can use the charge radii of a pair of mirror nuclei as one way to study the nature of neutron stars., There’s a force between the neutrons known as the strong interaction that works against gravity., These projects also underscore the importance of theorists and experimentalists working together.   

    From Michigan State University (US) : “Through the nuclear looking glass” 

    Michigan State Bloc

    From Michigan State University (US)

    03 November 2021

    1
    Scientists can use the charge radii of a pair of mirror nuclei as one way to study the nature of neutron stars. This pair is shown in the illustration in the looking glass. Image credit: Facility for Rare Isotope Beams.

    About 20 years ago, Michigan State University’s B. Alex Brown had an idea to reveal insights about a fundamental but enigmatic force at work in some of the most extreme environments in the universe.

    These environments include an atom’s nucleus and celestial bodies known as neutron stars, both of which are among the densest objects known to humanity. For comparison, matching the density of a neutron star would require squeezing all the Earth’s mass into a space about the size of Spartan Stadium.

    Brown’s theory laid the blueprints for connecting the properties of nuclei to neutron stars, but building that bridge with experiments would be challenging. It would take years and the unique capabilities of the DOE’s Thomas Jefferson National Accelerator Facility (US). The facility is a Department of Energy Office of Science (US) national laboratory in Virginia. So experimentalists got to work on a decades-long series of studies and Brown largely returned to his other projects.

    That is, until 2017. That’s when he said he started thinking about the beautiful precision experiments run by his colleague Kei Minamisono’s group at the National Superconducting Cyclotron Laboratory (US) at Michigan State University, and in the near-future at the Facility for Rare Isotope Beams, or FRIB. FRIB is a DOE-SC user facility at MSU that will start scientific user operation in early 2022.

    “It’s amazing how new ideas come to you,” said Brown, a professor of physics at FRIB and in MSU’s Department of Physics and Astronomy.

    The goal of this new idea was the same as his earlier theory, but it could be tested using what are known as “mirror nuclei” to provide a faster and simpler path to that destination.

    In fact, on Oct. 29, the team published a paper in the journal Physical Review Letters based on data from an experiment that took a few days to run. This comes on the heels of new data from the Jefferson Lab experiments that took years to acquire.

    “It’s quite incredible,” Brown said. “You can do experiments that take a few years to run and experiments that take a few days and get results that are very similar.”

    To be clear, the experiments in Michigan and Virginia are not competing. Rather, Krishna Kumar, a member and past chair of the Jefferson Lab Users Organization, called the experiments “wonderfully complementary.”

    “A detailed comparison of these measurements will allow us to test our assumptions and increase the robustness of connecting the physics of the very small — nuclei — to the physics of the very large — neutron stars,” said Kumar, who is also the Gluckstern Professor of Physics at The University of Massachusetts-Amherst (US). “The progress made in both experiment and theory on this broad topic underscores the importance and uniqueness of the capabilities of Jefferson Lab and NSCL, and the future will bring more such examples as new measurements are carried out at FRIB.”

    These projects also underscore the importance of theorists and experimentalists working together, especially when tackling fundamental mysteries of the universe. It was this type of collaboration that kicked off the Jefferson Lab’s experiments 20 years ago, and it’s this type of collaboration that will power future discoveries at FRIB.

    A mirror to examine the neutron skin

    One of the ironies here is that Brown hasn’t spent a lot of his time working on the two theories central to this story. Brown has published more than 800 scientific papers during his career, and the ones that inspired the experiments at NSCL and Jefferson Lab are distinct from his other work.

    “I work on many things and these are very isolated papers,” Brown said. Despite that, Brown shared them quickly. “I wrote both papers in a couple months.”

    When Brown completed the draft of his 2017 theory, he immediately shared it with Minamisono.

    “I remember I was at a conference when I got the email from Alex,” said Minamisono, a senior physicist at FRIB. “I was so excited when I read that paper.”

    The excitement came from Minamisono’s knowledge that his team could lead the experiments to test the paper’s ideas and from the theory’s implications for the cosmos.

    “This connects to neutron stars and that is so exciting as an experimentalist,” Minamisono said.

    Neutron stars are more massive than our sun yet they’re only about as big as Manhattan Island. Researchers can make accurate measurements for the mass of neutron stars, but getting exact numbers for their diameters is challenging.

    A better understanding of the push and pull of forces inside neutron stars would improve these size estimates, which is where nuclear physics comes in.

    A neutron star is born when a very large star becomes a supernova and explodes, leaving behind a core that is still more massive than our sun. The gravity of this massive leftover causes it to collapse on itself. As it collapses, the star also begins converting its matter — the stuff that makes it up — into neutrons. Hence, “neutron star.”

    There’s a force between the neutrons known as the strong interaction that works against gravity and helps puts the brakes on the collapse. This force is also in action in atomic nuclei, which are made up of neutrons and particles known as protons.

    “We know gravity, of course. There’s no issue there,” Brown said. “But we’re not so sure about what the strong interaction is for pure neutrons. There’s no laboratory on the Earth that has pure neutrons, so we make inferences from things we see in nuclei that have both protons and neutrons.”

    In atomic nuclei, the neutrons stick out a teensy bit, forming a thin, neutron-only layer that extends beyond the protons. This is called the neutron skin. Measuring the neutron skin enables researchers to learn about the strong force and, by extension, neutron stars.

    In the Jefferson Lab experiments, researchers sent electrons hurtling at lead and calcium nuclei. Based on how the electrons scatter or deflect from the nuclei, scientists could calculate upper and lower limits for the size of the neutron skin.

    For the NSCL experiments, the team needed to measure how much room the protons take up in a specific nickel nucleus. This is called the charge radius. In particular, the team examined the charge radius for nickel-54, a nickel nuclei or isotope with 26 neutrons. (All nickel isotopes have 28 protons, and those with 26 neutrons are called nickel-54 because the two numbers add up to 54.)

    What’s special about nickel-54 is that scientists already know the charge radius of its mirror nucleus, iron-54, an iron nucleus with 26 protons and 28 neutrons.

    “One nucleus has 28 protons and 26 neutrons. For the other, it’s flipped,” said Skyy Pineda, a lead author on the new research paper and a graduate student researcher on Minamisono’s team. By subtracting the charge radii, the researchers effectively remove the protons and are left with that thin neutron layer.

    “If you take the difference of the charge radii of the two nuclei, the result is the neutron skin,” Pineda said.

    To measure the charge radius of nickel-54, the team turned to its Beam Cooler and Laser Spectroscopy facility, abbreviated BECOLA. Using BECOLA, experimentalists overlap a beam of nickel-54 isotopes with a beam of laser light. Based on how the light interacts with the isotope beam, the Spartans can measure the nickel’s charge radius, Pineda said.

    Using Brown’s earlier theory, Jefferson Lab scientists needed on the order of a sextillion electrons for a measurement, or a trillion billion particles. Using the new theory, researchers instead need thousands, maybe millions of nuclei. That means that measurements that once required years can be replaced with experiments that take days.

    A future of discovery built on a history of teamwork

    This new research feels like the passing of a baton in a couple ways. For one, the Jefferson Lab experiments are entering their final phase, while FRIB stands poised to continue the exploration.

    FRIB itself represents another leg of the relay. BECOLA started running at NSCL and will continue operating at FRIB.

    Each leg builds on the last and on the collective work the runners have put in together.

    Again, that formula is nothing new. It’s what enabled a theorist at NSCL to inspire and inform experiments at a world-class lab in Virginia. What stands out about NSCL and FRIB, however, is that the user facilities are connected to a university, letting veterans and the next generation of leaders interact and share ideas that much sooner.

    “MSU is unique in having had NSCL and now FRIB. In most cases, labs like these aren’t integrated into a university campus,” said Kristian Koenig, a postdoctoral researcher on Minamisono’s team and a co-lead author on the new paper. “It gives everyone here a great opportunity.”

    Joining the MSU team on the Physical Review Letters publication were researchers from The Florida State University (US) along with The Technical University of Darmstadt [Technische Universität Darmstadt] (DE) and The GSI Helmholtz Centre for Heavy Ion Research [GSI Helmholtzzentrum für Schwerionenforschung] (DE).

    This work is supported in part by the National Science Foundation Grant No. PHY-14-30152, PHY-15-65546, PHY-18-11855, PHY-21-10365 and PHY-21-11185, the DOE-SC under Award No. DE-FG02-92ER40750, and German Research Foundation Project ID 279384907 SFB 1245.

    See the full article here .


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    Please help promote STEM in your local schools.

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    Michigan State Campus

    Michigan State University (US) is a public research university located in East Lansing, Michigan, United States. Michigan State University (US) was founded in 1855 and became the nation’s first land-grant institution under the Morrill Act of 1862, serving as a model for future land-grant universities.

    The university was founded as the Agricultural College of the State of Michigan, one of the country’s first institutions of higher education to teach scientific agriculture. After the introduction of the Morrill Act, the college became coeducational and expanded its curriculum beyond agriculture. Today, Michigan State University (US) is one of the largest universities in the United States (in terms of enrollment) and has approximately 634,300 living alumni worldwide.

    U.S. News & World Report ranks its graduate programs the best in the U.S. in elementary teacher’s education, secondary teacher’s education, industrial and organizational psychology, rehabilitation counseling, African history (tied), supply chain logistics and nuclear physics in 2019. Michigan State University (US) pioneered the studies of packaging, hospitality business, supply chain management, and communication sciences. Michigan State University (US) is a member of the Association of American Universities and is classified among “R1: Doctoral Universities – Very high research activity”. The university’s campus houses the National Superconducting Cyclotron Laboratory, the W. J. Beal Botanical Garden, the Abrams Planetarium, the Wharton Center for Performing Arts, the Eli and Edythe Broad Art Museum, the Facility for Rare Isotope Beams, and the country’s largest residence hall system.

    Research

    The university has a long history of academic research and innovation. In 1877, botany professor William J. Beal performed the first documented genetic crosses to produce hybrid corn, which led to increased yields. Michigan State University (US) dairy professor G. Malcolm Trout improved the process for the homogenization of milk in the 1930s, making it more commercially viable. In the 1960s, Michigan State University (US) scientists developed cisplatin, a leading cancer fighting drug, and followed that work with the derivative, carboplatin. Albert Fert, an Adjunct professor at MSU, was awarded the 2007 Nobel Prize in Physics together with Peter Grünberg.

    Today Michigan State University (US) continues its research with facilities such as the Department of Energy (US)-sponsored Plant Research Laboratory and a particle accelerator called the National Superconducting Cyclotron Laboratory [below]. The Department of Energy (US) Office of Science named Michigan State University as the site for the Facility for Rare Isotope Beams (FRIB). The $730 million facility will attract top researchers from around the world to conduct experiments in basic nuclear science, astrophysics, and applications of isotopes to other fields.

    In 2004, scientists at the Cyclotron produced and observed a new isotope of the element germanium, called Ge-60 In that same year, Michigan State University (US), in consortium with the University of North Carolina at Chapel Hill (US) and the government of Brazil, broke ground on the 4.1-meter Southern Astrophysical Research Telescope (SOAR) in the Andes Mountains of Chile.

    NSF NOIRLab NOAO Southern Astrophysical Research [SOAR ] telescope situated on Cerro Pachón, just to the southeast of Cerro Tololo on the NOIRLab NOAO AURA site at an altitude of 2,700 meters (8,775 feet) above sea level.

    The consortium telescope will allow the Physics & Astronomy department to study galaxy formation and origins. Since 1999, MSU has been part of a consortium called the Michigan Life Sciences Corridor, which aims to develop biotechnology research in the State of Michigan. Finally, the College of Communication Arts and Sciences’ Quello Center researches issues of information and communication management.


    The Michigan State University (US) Spartans compete in the NCAA Division I Big Ten Conference. Michigan State Spartans football won the Rose Bowl Game in 1954, 1956, 1988 and 2014, and the university claims a total of six national football championships. Spartans men’s basketball won the NCAA National Championship in 1979 and 2000 and has attained the Final Four eight times since the 1998–1999 season. Spartans ice hockey won NCAA national titles in 1966, 1986 and 2007. The women’s cross country team was named Big Ten champions in 2019.[12] In the fall of 2019, MSU student-athletes posted all-time highs for graduation success rates and federal graduation rates, according to NCAA statistics.

     
  • richardmitnick 3:23 pm on October 14, 2021 Permalink | Reply
    Tags: "Quarks and Antiquarks at High Momentum Shake the Foundations of Visible Matter", , , , DOE's Thomas Jefferson National Accelerator Facility (US), EMC effect: longstanding nuclear paradox,   

    From American Physical Society (US) : “Quarks and Antiquarks at High Momentum Shake the Foundations of Visible Matter” 

    AmericanPhysicalSociety

    From American Physical Society (US)

    10.14.21

    DOE’s Thomas Jefferson National Accelerator Facility (US) and DOE’s Fermi National Accelerator Laboratory (US) experiments present new results on nucleon structure

    Two independent studies have illuminated unexpected substructures in the fundamental components of all matter. Preliminary results using a novel tagging method could explain the origin of the longstanding nuclear paradox known as the EMC effect. Meanwhile, authors will share next steps after the recent observation of asymmetrical antimatter in the proton [Nature].

    1
    Artistic rendering of quarks in deuterium. Credit: Ran Shneor.

    Both groups will discuss their experiments at DOE’s Thomas Jefferson National Accelerator Facility and Fermilab during the 2021 Fall Meeting of the APS Division of Nuclear Physics. They will present the results and take questions from the press at a live virtual news briefing on October 12 at 2:15 p.m. EDT.

    One study presents new evidence on the EMC effect, identified nearly 40 years ago when researchers at European Organization for Nuclear Research [Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH) [CERN] discovered something surprising: Protons and neutrons bound in an atomic nucleus can change their internal makeup of quarks and gluons. But why such modifications arise, and how to predict them, remains unknown.

    For the first time, scientists have measured the EMC effect by tagging spectator neutrons, taking a major step toward solving the mystery.

    “We present initial and preliminary results from a new transformative measurement of a novel observable that provides direct insight into the origin of the EMC effect,” said Tyler T. Kutz, a postdoctoral researcher at The Massachusetts Institute of Technology (US) and Zuckerman Postdoctoral Scholar at The Tel Aviv University אוּנִיבֶרְסִיטַת תֵּל אָבִיב (IL), who will reveal the findings at the meeting.

    Inside the Backward Angle Neutron Detector (BAND) at Jefferson Lab, tagged spectator neutrons “split” the nuclear wave function into different sections. This process maps how momentum and density affect the structure of bound nucleons.

    The team’s initial results point to potential sizable, unpredicted effects. Preliminary observations suggest direct evidence that the EMC effect is connected with nucleon fluctuations of high local density and high momentum.

    “The results can have major implications for our understanding of the QCD structure of visible matter,” said Efrain Segarra, a graduate student at MIT working on the experiment. The research could shed light on the nature of confinement, strong interactions, and the fundamental composition of matter.

    A team from Fermilab found evidence that antimatter asymmetry also plays a crucial role in nucleon properties—a landmark observation published earlier this year in Nature. New analysis indicates that in the most extreme case, a single antiquark can be responsible for almost half the momentum of a proton.

    “This surprising result clearly shows that even at high momentum fractions, antimatter is an important part of the proton,” said Shivangi Prasad, a researcher at DOE’s Argonne National Laboratory (US). “It demonstrates the importance of nonperturbative approaches to the structure of the basic building block of matter, the proton.”

    Prasad will discuss the SeaQuest experiment that found more “down” antiquarks than “up” antiquarks within the proton. She will also share preliminary research on sea-quark and gluon distributions.

    “The SeaQuest Collaboration looked inside the proton by slamming a high-energy beam of protons into targets made of hydrogen (essentially protons) and deuterium (nuclei containing single protons and neutrons),” said Prasad.

    “Within the proton, quarks and antiquarks are held together by extremely strong nuclear forces—so great that they can create antimatter-matter quark pairs out of empty space!” she explained. But the subatomic pairings only exist for a fleeting moment before they annihilate.

    The antiquark results have renewed interest in several earlier explanations for antimatter asymmetry in the proton. Prasad plans to discuss future measurements that could test the proposed mechanisms.

    See the full article here .

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    Please help promote STEM in your local schools.

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    American Physical Society US)
    Physicists are drowning in a flood of research papers in their own fields and coping with an even larger deluge in other areas of physics. How can an active researcher stay informed about the most important developments in physics? Physics highlights a selection of papers from the Physical Review journals. In consultation with expert scientists, the editors choose these papers for their importance and/or intrinsic interest. To highlight these papers, Physics features three kinds of articles: Viewpoints are commentaries written by active researchers, who are asked to explain the results to physicists in other subfields. Focus stories are written by professional science writers in a journalistic style and are intended to be accessible to students and non-experts. Synopses are brief editor-written summaries.

     
  • richardmitnick 1:34 pm on May 1, 2021 Permalink | Reply
    Tags: "Unraveling the Secrets of Neutron Stars", DOE's Thomas Jefferson National Accelerator Facility (US), Pb Radius Experiment PREX at JLab,   

    From UMass Amherst : “Unraveling the Secrets of Neutron Stars” 

    U Mass Amherst

    From UMass Amherst

    April 29, 2021

    Neutron stars, the collapsed cores of dying massive stars, are one of the universe’s mysteries. With the exception of black holes, neutron stars are the smallest and densest things in existence. Thus, any insight into the nature of neutron stars helps illuminate the raw mechanics of the universe, but like black holes, they are difficult to observe directly.

    However, new research recently published in Physical Review Letters, to which Krishna Kumar, Gluckstern Professor of Physics, and his research group contributed, found some of the stars’ secrets here on earth – in a lump of lead.

    The international research team, known as Pb Radius Experiment PREX at JLab, which consists of over 90 scientists from 30 institutions, conducted their experiments at the DOE’s Thomas Jefferson National Accelerator Facility (US) in Virginia.

    The team noted that lead is a neutron-rich material – it has 126 neutrons to its 82 protons. These neutrons surround the protons, forming a “skin” that “bulges out beyond the protons in a heavy nucleus,” like lead’s, Kumar says. The question is why: why does the neutron skin bulge? By how much? And why does it matter?

    The PREx team is the first to observe this neutron skin using electron-scattering techniques, which involved an enormous machine called the Continuous Electron Beam Accelerator Facility (CEBAF).

    The facility shot a beam of electrons, whose spin was alternated 240 times per second, along a mile-long accelerator into a thin sheet of cryogenically cooled lead. “On average over the entire run, we knew where the right- and left-hand beams were, relative to each other, within a width of 10 atoms,” says Kumar, achieving the “sharpness” required to differentiate between the volumes occupied by neutrons compared to protons in the lead nucleus.

    What they discovered is that the neutron skin is about .28 millionths of a nanometer thick – nearly twice as thick as previously theorized. While only a fraction of a millionth of a nanometer might not seem like much at all, the implications are already sending waves through the physics world, in part because they relate to earlier astrophysical observations begun in 2017, when the global astronomy community trained dozens of telescopes on a pair of neutron stars that had collapsed into one another. This cataclysmic event, first discovered by the gravitational wave detector known as LIGO, was direct evidence that neutron star mergers are a significant source for the synthesis of heavy elements in the universe. LIGO’s data provided new information on the nuclear equation of state.

    Milliseconds before the final merger, the two neutron stars were so close together that they deformed into “teardrops.” What Kumar calls the “tidal deformability” of the neutron stars is affected by dense matter characteristics similar to the neutron skin in the nucleus of lead – a linkage made possible by the nuclear equation of state. “The same nuclear equation of state that governs the neutron skin of the lead nucleus impacts the bulk properties of neutron stars,” Kumar says.

    Though the PREx team only released its research results this week, the Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz](DE) in Mainz, Germany, is already planning follow-up experiments.

    1
    The Continuous Electron Beam Accelerator at Thomas Jefferson National Accelerator Facility.

    2
    Krishna Kumar and team members at Thomas Jefferson National Accelerator Facility.

    Pb Radius Experiment PREX at JLab

    See the full article here .

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    Stem Education Coalition

    U Mass Amherst campus

    UMass Amherst, the Commonwealth’s flagship campus, is a nationally ranked public research university offering a full range of undergraduate, graduate and professional degrees.

    As the flagship campus of America’s education state University of Massachusetts Amherst is the leader of the public higher education system of the Commonwealth, making a profound, transformative impact to the common good. Founded in 1863, we are the largest public research university in New England, distinguished by the excellence and breadth of our academic, research and community outreach programs. We rank 29th among the nation’s top public universities, moving up 11 spots in the past two years in the U.S. News & World Report’s annual college guide.

     
  • richardmitnick 4:36 pm on April 30, 2021 Permalink | Reply
    Tags: "Physicists suggest Neutron stars should be bigger than they are", , , , , DOE's Thomas Jefferson National Accelerator Facility (US), Neutron stars are the collapsed cores of dead stars., Parity-violating electron scattering, PREX Collaboration, University of Manitoba (CA)   

    From University of Manitoba (CA) with DOE’s Thomas Jefferson National Accelerator Facility (US): “Physicists suggest Neutron stars should be bigger than they are” 

    From University of Manitoba (CA)

    April 30, 2021

    1
    Photo credit. Kent Paschke. Jefferson Lab. Hall A.

    UM physicists Drs. Juliette Mammei and Micheal Gericke are part of an international research experiment that has made the most precise measurement yet of the neutron distribution in a heavy nucleus, with implications for the structure of neutron stars. Their paper has just been published in the Physical Review Letters.

    The Lead Radius Experiment (PREX Collaboration at the DOE’s Thomas Jefferson National Accelerator Facility (US) has determined the thickness of this neutron-rich skin in lead-208, a stable isotope with 44 more neutrons than protons. The measurement, which addresses questions relating to all four fundamental forces of nature, yields insight into the structure of neutron stars, the densest objects in our universe besides black holes.

    Neutron stars are the collapsed cores of dead stars; they are so dense that experts aren’t quite sure what lies at their core. It’s been suggested that they may be the source of axions, a candidate to explain dark matter.

    Mammei explains, sometimes, examining the microscopic behaviors of subatomic particles can tell you more about the forces that act at a cosmic scale, than peering at a star through a telescope.

    “We can learn about neutron stars, which are more than 15 orders of magnitude larger and more massive than earth-bound nuclei, by measuring how much the neutrons in a pure isotope of lead stick out from the protons.”

    2
    The primary detector elements for the PREX-2 experiment, with the light-tight covers, removed. The transparent quartz crystals (mounted on thin rails, at an angle to the thick aluminum frame) collect light from the passage of more than 2 billion high-energy electrons per second.

    “We use a technique called parity-violating electron scattering because the weak charge of the proton is close to zero, but that of the neutron is large. This allows us to make a measurement of the energy cost in having unequal numbers of neutrons and protons, which in turn tells us about the equation of the state of neutron matter.

    This will help in determining the phase diagram of nuclear matter, much like the phase diagram for water, which at different temperatures and pressures can be water, ice, or steam. Only in this case, it can help determine if the neutrons in a neutron star stay together as neutrons or have a phase change to quark matter, explains Mammei”

    3
    PREX-2 collaborators Sanghwa Park, Kent Paschke, and Simona Malace discuss improvements to a detector.

    Another benefit, says Mammei, is that the PREX experiment also provides a valuable opportunity to study the upgraded accelerator in preparation for the future MOLLER experiment, a bold project that will peer inside fundamental particles, called Measurement Of a Lepton Lepton Electroweak Reaction (MOLLER).

    See the full article here .

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    JLab campus

    DOE’s Thomas Jefferson National Accelerator Facility (US) is supported by the Office of Science of the U.S. Department of Energy. DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, visit science.energy.gov.

    Jefferson Science Associates, LLC, a joint venture of the Southeastern Universities Research Association, Inc. and PAE Applied Technologies, manages and operates the Thomas Jefferson National Accelerator Facility for the U.S. Department of Energy’s Office of Science.

    History

    DOE’s Thomas Jefferson National Accelerator Facility(US) was established in 1984 (first initial funding by DOE, Department of Energy) as the Continuous Electron Beam Accelerator Facility (CEBAF); the name was changed to Thomas Jefferson National Accelerator Facility in 1996. The full funding for construction was appropriated by US Congress in 1986 and on February 13, 1987, the construction of the main component, the CEBAF accelerator begun. First beam was delivered to experimental area on 1 July 1994. The design energy of 4 GeV for the beam was achieved during the year 1995. The laboratory dedication took place 24 May 1996 (at this event the name was also changed). Full initial operations with all three initial experiment areas online at the design energy was achieved on June 19, 1998. On August 6, 2000 the CEBAF reached “enhanced design energy” of 6 GeV. In 2001, plans for an energy upgrade to 12 GeV electron beam and plans to construct a fourth experimental hall area started. The plans progressed through various DOE Critical Decision-stages in the 2000s decade, with the final DOE acceptance in 2008 and the construction on the 12 GeV upgrade beginning in 2009. May 18, 2012 the original 6 GeV CEBAF accelerator shut down for the replacement of the accelerator components for the 12 GeV upgrade. 178 experiments were completed with the original CEBAF.

    In addition to the accelerator, the laboratory has housed and continues to house a free electron laser (FEL) instrument. The construction of the FEL started 11 June 1996. It achieved first light on June 17, 1998. Since then, the FEL has been upgraded numerous times, increasing its power and capabilities substantially.

    Jefferson Lab was also involved in the construction of the Spallation Neutron Source (SNS) at DOE’s Oak Ridge National Laboratory (US). Jefferson built the SNS superconducting accelerator and helium refrigeration system. The accelerator components were designed and produced 2000–2005.

    Accelerator

    The laboratory’s main research facility is the CEBAF accelerator, which consists of a polarized electron source and injector and a pair of superconducting RF linear accelerators that are 7/8-mile (1400 m) in length and connected to each other by two arc sections that contain steering magnets.

    As the electron beam makes up to five successive orbits, its energy is increased up to a maximum of 6 GeV (the original CEBAF machine worked first in 1995 at the design energy of 4 GeV before reaching “enhanced design energy” of 6 GeV in 2000; since then the facility has been upgraded into 12 GeV energy). This leads to a design that appears similar to a racetrack when compared to the classical ring-shaped accelerators found at sites such as European Organization for Nuclear Research [Organisation européenne pour la recherche nucléaire](CH) or DOE’s Fermi National Accelerator Laboratory(US). Effectively, CEBAF is a linear accelerator, similar to DOE’s SLAC National Accelerator Laboratory (US) at Stanford University (US), that has been folded up to a tenth of its normal length.

    The design of CEBAF allows the electron beam to be continuous rather than the pulsed beam typical of ring shaped accelerators. (There is some beam structure, but the pulses are very much shorter and closer together.) The electron beam is directed onto three potential targets (see below). One of the distinguishing features of Jefferson Lab is the continuous nature of the electron beam, with a bunch length of less than 1 picosecond. Another is Jefferson Lab’s use of superconducting Radio Frequency (SRF) technology, which uses liquid helium to cool niobium to approximately 4 K (−452.5 °F), removing electrical resistance and allowing the most efficient transfer of energy to an electron. To achieve this, Jefferson Lab houses the world’s largest liquid helium refrigerator, and it was one of the first large-scale implementations of SRF technology. The accelerator is built 8 meters below the Earth’s surface, or approximately 25 feet, and the walls of the accelerator tunnels are 2 feet thick.

    The beam ends in four experimental halls, labelled Hall A, Hall B, Hall C, and Hall D. Each hall contains specialized spectrometers to record the products of collisions between the electron beam or with real photons and a stationary target. This allows physicists to study the structure of the atomic nucleus, specifically the interaction of the quarks that make up protons and neutrons of the nucleus.

    With each revolution around the accelerator, the beam passes through each of the two LINAC accelerators, but through a different set of bending magnets in semi-circular arcs at the ends of the linacs. The electrons make up to five passes through the linear accelerators.

    When a nucleus in the target is hit by an electron from the beam, an “interaction”, or “event”, occurs, scattering particles into the hall. Each hall contains an array of particle detectors that track the physical properties of the particles produced by the event. The detectors generate electrical pulses that are converted into digital values by analog-to-digital converters (ADCs), time to digital converters (TDCs) and pulse counters (scalers).

    This digital data is gathered and stored so that the physicist can later analyze the data and reconstruct the physics that occurred. The system of electronics and computers that perform this task is called a data acquisition system.

    12 GeV upgrade

    As of June 2010, construction began on a $338 million upgrade to add an end station, Hall D, on the opposite end of the accelerator from the other three halls, as well as to double beam energy to 12 GeV. Concurrently, an addition to the Test Lab, (where the SRF cavities used in CEBAF and other accelerators used worldwide are manufactured) was constructed.

    As of May 2014, the upgrade achieved a new record for beam energy, at 10.5 GeV, delivering beam to Hall D.

    As of December 2016, the CEBAF accelerator delivered full-energy electrons as part of commissioning activities for the ongoing 12 GeV Upgrade project. Operators of the Continuous Electron Beam Accelerator Facility delivered the first batch of 12 GeV electrons (12.065 Giga electron Volts) to its newest experimental hall complex, Hall D.

    In September 2017, the official notification from the DOE of the formal approval of the 12 GeV upgrade project completion and start of operations was issued. By spring 2018, all fours research areas were successfully receiving beam and performing experiments. On 2 May 2018 the CEBAF 12 GeV Upgrade Dedication Ceremony took place.

    As of December 2018, the CEBAF accelerator delivered electron beams to all four experimental halls simultaneously for physics-quality production running.

    The University of Manitoba (CA) (U of M, UMN, or UMB) is a public university in the province of Manitoba, Canada. Located in Winnipeg and founded in 1877, it was Western Canada’s first university. The university maintains a reputation as a top research-intensive post-secondary educational institution and conducts more research annually than any other university in the region. It is the largest university both by total student enrollment and campus area in the province of Manitoba, and the 17th largest in all of Canada. The university’s raised admissions standards, wide array of professional disciplines, and global outreach have resulted in one of the most diverse student bodies in Western Canada. The campus includes both Faculties of Law and Medicine, and boasts hundreds of degree programs.

    As of 2010, there have been 96 Rhodes Scholars from the University of Manitoba, more than from any other university in Western Canada.

     
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