Bulletin of the American Physical Society
APS April Meeting 2021
Volume 66, Number 5
Saturday–Tuesday, April 17–20, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session G21: Instrumentation IILive
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Sponsoring Units: DNP Chair: Evangeline Downie, GWU |
Sunday, April 18, 2021 8:30AM - 8:42AM Live |
G21.00001: A new gamma-ray facility at HIGS: The Clover array U. Friman-Gayer, A.D. Ayangeakaa, R.V.F. Janssens, X.K.-H. James, S.R. Johnson, M Emamian, S. Finch, M.P. Carpenter, J Isaak, D. Savran, B. Loeher, O. Papst A new gamma-ray facility has recently been commissioned at the HIGS facility at TUNL. The clover array is composed of 8 HPGe detectors of the clover type as well as of 12 CeBr$_3$ scintillators. The facility is expandable to 12 clover systems, and can also accommodate other scintillators as well as other types of detectors as needed. This setup is designed to enable multi-parameter coincidence measurements and will have sub-nanosecond timing capabilities. It will also take full advantage of the increased gamma-ray fluxes which have recently become available at HIGS. Digital electronics is used for signal processing. The facility has been successfully commissioned very recently in a nuclear resonance fluorescence measurement. The performance of the full array will be discussed based on the data from this first experiment. [Preview Abstract] |
Sunday, April 18, 2021 8:42AM - 8:54AM Live |
G21.00002: Design and Operation of a Penning Ion Trap Source for the CHIP-TRAP Mass Spectrometer Madhawa Horana Gamage, Nadeesha Gamage, Ramesh Bhandari, Matthew Redshaw In this presentation, I will discuss the design and operation of a Penning Ion Trap (PIT) source that we have developed at Central Michigan University (CMU). It is similar to in concept to a PIG source, but produces small bunches of $\sim$100s to 1000s of ions from minimal gas samples in short duration ($\sim$1 $\mu$s) pulses. It is comprised of a cylindrical trap structure consisting of a ring and two end caps, inside a 0.55 T permanent neodymium ring magnet with a trap volume of about 0.8 cm$^{3}$. Ions are produced by electron impact ionization of gas admitted into the trap via a precision leak valve using a $\sim$1 $\mu$A electron beam from a thermal emitter applied for typically 1 ms. Ions produced within the trapping region are automatically confined and stored for a period of typically 5 ms before being released from the trap by lowering the voltage on one of the end caps in about 250 ns. The PIT source is incorporated into the CMU High Precision Penning Trap (CHIP-TRAP) mass spectrometer that we are currently developing at CMU. CHIP-TRAP aims to perform measurements on stable and long-lived radioactive isotopes, some of which will be supplied by the PIT source. [Preview Abstract] |
Sunday, April 18, 2021 8:54AM - 9:06AM Live |
G21.00003: Saturation Corrections for the High Momentum Spectrometer in Hall C at Jefferson Lab Jacob Murphy, Mark Jones With the 12 GeV upgrade at Jefferson Lab, experiments in Hall C require precise measurements of particles at high momenta in the High Momentum Spectrometer (HMS). The HMS central momentum ranges from 0.5 to 7.5 GeV/c. However, when set above 5 GeV/c, saturation effects begin to occur in the dipole and quadrupole magnets of the HMS. These saturation effects significantly affect both the angle and momentum reconstruction of the particle, information which is essential for precise cross section measurements. I will present the results of a new magnetic optics calibration for correcting saturation effects at a central momentum of 6.59 GeV/c. This calibration was performed in two parts, first using Deep Inelastic Scattering data with a carbon foil target and a sieve slit to calibrate angle reconstruction, then using elastic scattering off a hydrogen target to calibrate momentum reconstruction. [Preview Abstract] |
Sunday, April 18, 2021 9:06AM - 9:18AM Live |
G21.00004: Analysis of Backgrounds and Kinematic Factors for PREX-2 and CREX Devi Adhikari PREX-2 and CREX took place in Hall A at Jefferson Lab in 2019/2020 and measured the parity-violating asymmetry ($A_{pv}$) in $^{208}$Pb and $^{48}$Ca, respectively, using an electroweak interaction probe. The measurements are statistics limited and require extreme control over systematic uncertainties. Some of the major systematics include: contamination from rescattering, inelastic backgrounds, and sensitivity of finite acceptance in $Q^2$ normalization. The High-Resolution Spectrometers (HRSs) of the Hall A allow precise alignment of the detectors within the kinematic acceptance -- minimizing contamination from inelastic events, which have largely unknown asymmetries. There are also some possibilities for the inelastically scattered electrons, and the electrons in the radiative tail, to reach the integrating detectors by rescattering off the spectrometer walls. Finally, the measured asymmetry is averaged over a range of $Q^2$ across the finite acceptance of the HRSs, which needs to be accounted for to make an accurate theoretical interpretation of the asymmetry. In this talk, we will discuss the corrections to $A_{pv}$ and the systematic error contributions due to these sources. [Preview Abstract] |
Sunday, April 18, 2021 9:18AM - 9:30AM Live |
G21.00005: Low-Energy Radiation Detection with Superconducting Tunnel Junctions Spencer Fretwell The detection of low energy (sub-keV) radiation from nuclear decay is typically fraught with technical challenges due to induced backgrounds from the much higher energy radiation in these processes. Nonetheless, there are a number of important measurements of eV-scale decay products related to tests of fundamental symmetries, nuclear structure, nuclear astrophysics, and nuclear medicine on short-lived radionuclides that are outstanding. In order to perform such measurements, new detection methods are required which are sensitive to these energy regimes, while still remaining practical for nuclear physics. In this talk, I will briefly describe recent nuclear physics experiments involving modern quantum sensors, focusing specifically on what superconducting tunnel junction (STJs) are capable of, and where these experiments may go in the future. [Preview Abstract] |
Sunday, April 18, 2021 9:30AM - 9:42AM Live |
G21.00006: Design and Commissioning Progress of HCAL-J: A Segmented Hadron Calorimeter with Excellent Timing and Position Resolution Scott Barcus The design and commissioning progress for a new segmented hadron calorimeter (HCAL-J), constructed to measure the energy of several GeV protons and neutrons, will be presented. HCAL-J is composed of 288 individual calorimeter modules measuring 15cm$\times$15cm$\times$1m. These modules consist of 40 layers of iron, which cause the hadrons to shower, alternating with 40 layers of scintillator, which sample the energy. HCAL-J has a time resolution of 0.5 ns, a position resolution as good as 3-4 cm, and detects protons and neutrons with near identical efficiency. This calorimeter will be used in the upcoming Super BigBite Spectrometer (SBS) experiments, measuring the nucleon form factors in Jefferson Lab's Hall A. HCAL-J's role in the measurement of the neutron magnetic form factor, $G_M^n$, will be explained. Efforts to implement HCAL-J's trigger, using neural networks loaded onto FPGAs, will also be discussed. [Preview Abstract] |
Sunday, April 18, 2021 9:42AM - 9:54AM Live |
G21.00007: Simulation Study of Electromagnetic Endcap Calorimeter Jihee Kim The Electron-Ion Collider (EIC) will be an ultimate experimental facility to explore the gluon-dominated regime in nucleons and nuclei, shedding light on their structure and the interactions within. Among four detector concepts driven by the EIC community, the Timing Optimized PID Silicon Detector for the EIC (TOPSiDE) is introduced as in the ANL concept of an EIC detector. The TOPSiDE detector concept is designed to utilize ultra-fast silicon devices for particle identification in the central detector region with full 4$\pi$ coverage. In the electron-beam direction, a crystal endcap calorimeter is added for the scattered and decay lepton identification and precision energy resolution focusing on DVMP/DVCS exclusive measurements for the -3.5 $< \eta <$ -2 range. It is composed of lead tungstate (PbWO$_{4}$) crystals bars with a length of 22.5$X_{0}$, and a transverse size of 2$\times$2 cm$^2$ which includes the small Moli\`ere radius of 2~cm. In this work, I will present the energy resolution performance in the energy range up to 30~GeV of scattered leptons using homogeneous crystal endcap calorimeter in the TOPSiDE detector concept of the EIC detector. [Preview Abstract] |
Sunday, April 18, 2021 9:54AM - 10:06AM Live |
G21.00008: An Apparatus for Light Attenuation and Scattering Measurements in Highly Transparent Media Jake Hecla, Steven Dazeley, Oluwatomi Akindele, Adam Bernstein This paper presents a design for a horizontal, adjustable path-length attenuation and scattering measurement device that has successfully observed attenuation lengths in excess of 130m in deionized (DI) water. Absolute measurements of attenuation and scattering in water have proven challenging, and values reported in literature show high variance. This system bypasses limitations on prior designs by using an optical path which remains purely in the liquid medium. Path-length adjustment is performed using a hydraulic system to move an optical element (sensor or retroreflector) within the 5m fluid-filled cell. Scattering measurements are performed at multiple ports along the beam axis, where a system of adjustable polarizers and attenuators allows separation of Rayleigh and Mie scattering components. Attenuation measurements have been performed with DI water which show excellent agreement with past experimental results across the visible spectrum. Scattering measurements in optically pure water are ongoing. Subsequently, the system will be used to characterize the optical properties of water-based liquid scintillator, a medium under consideration as a fill for large scale neutrino detectors.~ [Preview Abstract] |
Sunday, April 18, 2021 10:06AM - 10:18AM Live |
G21.00009: MOLLER: High Precision Electron Beam Control Caryn Palatchi The MOLLER experiment at Jefferson Laboratory will measure the Moller (electron-electron scattering) parity-violating asymmetry, providing an unparalleled precision on the electroweak mixing angle. It will be part of a new generation of ultra high precision electroweak experiments. To achieve the parity quality beam necessary for the small systematic uncertainties required in MOLLER, it is critical to control helicity correlated false asymmetries in the polarized electron beam. Innovative techniques in the polarized electron source are required including using a newly installed RTP Pockels cell system in the laser optics of the source. This talk will describe the development of the this new RTP Pockels cell system, a critical component of the experiment. It will demonstrate precision control capabilities at the nano-meter level within the injector source which shows extreme promise for the future MOLLER Experiment. [Preview Abstract] |
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