Engineering topics

Tsang, R. H. M.

Publications and source records attributed to Tsang, R. H. M..

5 records

DOE OSTI2023

Search for MeV electron recoils from dark matter in EXO-200

We present a search for electron-recoil signatures from the charged-current absorption of fermionic dark matter using the EXO-200 detector. We report an average electron-recoil background rate of 6.8×10 4 ⁢cts ⁢kg −1 yr −1 keV −1 above 4 MeV and find no statistically significant excess over our background projection. Using a total 136 Xe exposure of 234.1 kg yr, we exclude new parameter space for the charged-current absorption cross section for dark matter masses between 𝑚𝜒=2.6–11.6 MeV with a minimum of 6×10 −51 cm 2 at 8.3 MeV at the 90% confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2020

Cosmogenic activation of silicon

In the production of 3 H, 7 Be, and 22 Na by interactions of cosmic-ray particles with silicon can produce radioactive backgrounds in detectors used to search for rare events. Through controlled irradiation of silicon CCDs and wafers with a neutron beam that mimics the cosmic-ray neutron spectrum, followed by direct counting, we determined that the production rate from cosmic-ray neutrons at sea level is (112 ± 24) atoms/( kg day ) for 3 H, (8.1 ± 1.9) atoms/( kg day ) for 7 Be, and (43.0 ± 7.2) atoms/( kg day ) for 22 Na . Complementing these results with the current best estimates of activation cross sections for cosmic-ray particles other than neutrons, we obtain a total sea-level cosmic-ray production rate of (124 ± 25) atoms/(kg day) for 3 H, (9.4 ± 2.0) atoms/( kg day ) for 7 Be, and (49.6 ± 7.4) atoms/( kg day ) for 22 Na. These measurements will help constrain background estimates and determine the maximum time that silicon-based detectors can remain unshielded during detector fabrication before cosmogenic backgrounds impact the sensitivity of next-generation rare-event searches.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2019

GEANT4 models of HPGe detectors for radioassay

Radiation transport models of two high purity germanium detectors, GeII and GeIII, located at the University of Alabama have been created in GEANT4 (Agostinelli et al., 2003) [1].These detectors have been used extensively for radioassay measurements of materials used in various low background experiments. The two models have been validated against actual data under several scenarios typically seen in radioassay measurements. Furthermore, the systematic uncertainties of the models for GeII and GeIII are estimated to be ~12% and ~9% respectively.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2016

Measurement of cosmic-ray muons and muon-induced neutrons in the Aberdeen Tunnel Underground Laboratory

In this study, we have measured the muon flux and production rate of muon-induced neutrons at a depth of 611 m water equivalent. Our apparatus comprises three layers of crossed plastic scintillator hodoscopes for tracking the incident cosmic-ray muons and 760 L of a gadolinium-doped liquid scintillator for producing and detecting neutrons. The vertical muon intensity was measured to be I μ = (5.7±0.6)×10 –6 cm –2 s –1 sr –1 . The yield of muon-induced neutrons in the liquid scintillator was determined to be Y n = (1.19 ± 0.08(stat) ± 0.21(syst)) × 10 –4 neutrons/(μ•g•cm –2 ). A fit to the recently measured neutron yields at different depths gave a mean muon energy dependence of < E μ > 0.76±0.03 for liquid-scintillator targets.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2015

Neutron calibration sources in the Daya Bay experiment

We describe the design and construction of the low rate neutron calibration sources used in the Daya Bay Reactor Anti-neutrino Experiment. Such sources are free of correlated gamma-neutron emission, which is essential in minimizing induced background in the anti-neutrino detector. Thus, the design characteristics have been validated in the Daya Bay anti-neutrino detector.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗