182 research outputs found
Measurement of the elastic scattering cross section of neutrons from argon and neon
Background: The most significant source of background in direct dark matter
searches are neutrons that scatter elastically from nuclei in the detector's
sensitive volume. Experimental data for the elastic scattering cross section of
neutrons from argon and neon, which are target materials of interest to the
dark matter community, were previously unavailable. Purpose: Measure the
differential cross section for elastic scattering of neutrons from argon and
neon in the energy range relevant to backgrounds from (alpha,n) reactions in
direct dark matter searches. Method: Cross-section data were taken at the
Triangle Universities Nuclear Laboratory (TUNL) using the neutron
time-of-flight technique. These data were fit using the spherical optical
model. Results: The differential cross section for elastic scatting of neutrons
from neon at 5.0 and 8.0 MeV and argon at 6.0 MeV was measured. Optical-model
parameters for the elastic scattering reactions were determined from the best
fit to these data. The total elastic scattering cross section for neon was
found to differ by 6% at 5.0 MeV and 13% at 8.0 MeV from global optical-model
predictions. Compared to a local optical-model for 40Ar, the elastic scattering
cross section was found to differ from the data by 8% at 6.0 MeV. Conclusions:
These new data are important for improving Monte-Carlo simulations and
background estimates for direct dark matter searches and for benchmarking
optical models of neutron elastic scattering from these nuclei
Low-Background gamma counting at the Kimballton Underground Research Facility
The next generation of low-background physics experiments will require the
use of materials with unprecedented radio-purity. A gamma-counting facility at
the Kimballton Underground Research Facility (KURF) has been commissioned to
perform initial screening of materials for radioactivity primarily from
nuclides in the 238U and 232Th decay chains, 40K and cosmic-ray induced
isotopes. The facility consists of two commercial low-background high purity
germanium (HPGe) detectors. A continuum background reduction better than a
factor of 10 was achieved by going underground. This paper describes the
facility, detector systems, analysis techniques and selected assay results.Comment: 7 pages, 7 figures. Submitted to NIM
Measurement of airborne fission products in Chapel Hill, NC, USA from the Fukushima Dai-ichi reactor accident
We present measurements of airborne fission products in Chapel Hill, NC, USA,
from 62 days following the March 11, 2011, accident at the Fukushima Dai-ichi
nuclear power plant. Airborne particle samples were collected daily in air
filters and radio-assayed with two high-purity germanium (HPGe) detectors. The
fission products I-131 and Cs-137 were measured with maximum activities of 4.2
+/- 0.6 mBq/m^3 and 0.42 +/- 0.07 mBq/m^3 respectively. Additional activity
from I-131, I-132, Cs-134, Cs-136, Cs-137 and Te-132 were measured in the same
air filters using a low-background HPGe detector at the Kimballton Underground
Research Facility (KURF).Comment: 10 pages, 4 figure
- …