NSUF 23-1840: Measurement of 254-eV Nuclear Recoils in Germanium
Nuclear recoils within a high-purity germanium detector (HPGe) will be produced via a three-step sequence: thermal neutron capture on Ge-72, excitation to a metastable nuclear state of Ge-73m, and decay back to the ground state via gamma emission. Low energy, <1 keV, nuclear recoils will be produced from the emission of high energy, 5.8 MeV gamma rays. A University of Michigan (UM)-owned Ortec GLP low-energy germanium detector will serve as both the nuclear target for irradiation as well as the measurement instrument for the induced nuclear recoils. The detector will be irradiated with 3.4x10^6 n/cm^2/s, while a large BGO detector will be used for tagging the 5.8 MeV gamma ray. All waveforms will be digitized and saved using modern small-footprint CAEN data acquisition systems for offline analysis. A one-week campaign at the Ohio State University Thermal Neutron Beam Facility is envisioned. The first day will be reserved for set-up and calibration. Three and a half days will be reserved for data taking of the experiment. The last half-day will be used for tear down and packing up. This experiment only requires access to the thermal neutron beam and would not interfere with any experiments at other research facilities at the OSU reactor. The ionization and/or scintillation produced by nuclear recoils is a key methodology of neutron (and neutral particle) measurement. The ratio of ionization/scintillation as a function of nucleon kinetic energy (denoted the quenching factor) is well understood at higher energies above ~100 keV; however, experimental measurements under ~10keVnr vary considerably both for individual detector materials as well as from detector material to detector material. This experiment aims at the precision measurement of the ionization produced via ultra-low energy nuclear recoils utilizing modern digitizer and data analysis techniques for better interpretation of the underlying physics. Saving the raw digitized waveforms, as opposed to only saving pulse height data via multi-channel analyzers, will also allow for the reconciliation of several conflicting measurements of low-energy nuclear recoils in germanium specifically. A better understanding of the micro-physics and detector response of low-energy nuclear recoils will inform both the expected response of next-generation neutral particle detectors. It will also enable the evaluation of the viability of reactor monitoring via coherent elastic neutrino-nucleus scattering (CEvNS), an interaction directly analogous to neutrons scattering off detector nuclei.
Additional Info
| Field | Value |
|---|---|
| Abstract | Nuclear recoils within a high-purity germanium detector (HPGe) will be produced via a three-step sequence: thermal neutron capture on Ge-72, excitation to a metastable nuclear state of Ge-73m, and decay back to the ground state via gamma emission. Low energy, <1 keV, nuclear recoils will be produced from the emission of high energy, 5.8 MeV gamma rays. A University of Michigan (UM)-owned Ortec GLP low-energy germanium detector will serve as both the nuclear target for irradiation as well as the measurement instrument for the induced nuclear recoils. The detector will be irradiated with 3.4x10^6 n/cm^2/s, while a large BGO detector will be used for tagging the 5.8 MeV gamma ray. All waveforms will be digitized and saved using modern small-footprint CAEN data acquisition systems for offline analysis. A one-week campaign at the Ohio State University Thermal Neutron Beam Facility is envisioned. The first day will be reserved for set-up and calibration. Three and a half days will be reserved for data taking of the experiment. The last half-day will be used for tear down and packing up. This experiment only requires access to the thermal neutron beam and would not interfere with any experiments at other research facilities at the OSU reactor. The ionization and/or scintillation produced by nuclear recoils is a key methodology of neutron (and neutral particle) measurement. The ratio of ionization/scintillation as a function of nucleon kinetic energy (denoted the quenching factor) is well understood at higher energies above ~100 keV; however, experimental measurements under ~10keVnr vary considerably both for individual detector materials as well as from detector material to detector material. This experiment aims at the precision measurement of the ionization produced via ultra-low energy nuclear recoils utilizing modern digitizer and data analysis techniques for better interpretation of the underlying physics. Saving the raw digitized waveforms, as opposed to only saving pulse height data via multi-channel analyzers, will also allow for the reconciliation of several conflicting measurements of low-energy nuclear recoils in germanium specifically. A better understanding of the micro-physics and detector response of low-energy nuclear recoils will inform both the expected response of next-generation neutral particle detectors. It will also enable the evaluation of the viability of reactor monitoring via coherent elastic neutrino-nucleus scattering (CEvNS), an interaction directly analogous to neutrons scattering off detector nuclei. |
| Award Announced Date | 2023-02-08T10:48:24.577 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Raymond Cao |
| Irradiation Facility | Ohio State University Research Reactor |
| PI | Igor Jovanovic |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 4513 |