In this work, PENELOPE2008 and MCNP5 software packages were used to investigate the effect of simulation parameters such as cut-off energy of photons and electrons on the detector response function and peak escape intensity to assess their influence on the efficiency determination. The results showed a general agreement between the two codes, however both the intensity of escape peaks and total efficiency computed with PENELOPE2008 are higher than those obtained with MCNP5. Moreover, the calculated efficiencies are typically 8% higher than what is experimentally found in the low energy range. Further investigation was required to obtain better agreement and lead to better estimate of the real germanium crystal dimensions and dead layer.
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http://dx.doi.org/10.1016/j.apradiso.2013.03.065 | DOI Listing |
J Low Temp Phys
November 2024
Princeton University, Princeton, NJ USA.
The Simons Observatory (SO) is a cosmic microwave background (CMB) experiment located in the Atacama Desert in Chile that will make precise temperature and polarization measurements over six spectral bands ranging from 27 to 285 GHz. Three small aperture telescopes (SATs) and one large aperture telescope (LAT) will house 60,000 detectors and cover angular scales between one arcminute and tens of degrees. We present the performance of the dichroic, low-frequency (LF) lenslet-coupled sinuous antenna transition-edge sensor (TES) bolometer arrays with bands centered at 27 and 39 GHz.
View Article and Find Full Text PDFSensors (Basel)
December 2024
Freiburg Materials Research Center, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg im Breisgau, Germany.
Nuclear power plant decommissioning requires the rapid and accurate classification of radioactive waste in narrow spaces and under time constraints. Photon-counting detector technology offers an effective solution for the quick classification and detection of radioactive hotspots in a decommissioning environment. This paper characterizes a 5 mm CdTe Timepix3 detector and evaluates its feasibility as a single-layer Compton camera.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Division of Space, Ecological, Arctic, and Resource-limited (SPEAR) Medicine, Department of Emergency Medicine, Massachusetts General Hospital, Boston, MA 02114.
One of the most surprising and important findings of the first human landings on the Moon was the discovery of a very fine layer of lunar dust covering the entire surface of Moon along with the negative impacts of this dust on the well-being and operational effectiveness of the astronauts, their equipment, and instrumentation. The United States is now planning for human missions to Mars, a planet where dust can also be expected to be ubiquitous for many or most landing sites. For these missions, the design and operations of key hardware systems must take this dust into account, especially when related to crew health and safety.
View Article and Find Full Text PDFSci Rep
January 2025
School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
Nanoscale Fourier transform infrared (Nano-FTIR) imaging and spectroscopy correlated with photoluminescence measurements of lunar Apollo samples with different surface radiation exposure histories reveal distinct physical and chemical differences associated with space weathering effects. Analysis of two sample fragments: an ilmenite basalt (12016) and an impact melt breccia (15445) show evidence of intrinsic or delivered Nd and an amorphous silica glass component on exterior surfaces, whereas intrinsic Cr and/or trapped electron states are limited to interior surfaces. Spatially localized 1050 cm/935 cm band ratios in Nano-FTIR hyperspectral maps may further reflect impact-induced shock nanostructures, while shifts in silicate band positions indicate accumulated radiation damage at the nanoscale from prolonged space weathering due to micrometeorites, solar wind, energetic x-rays and cosmic ray bombardment.
View Article and Find Full Text PDFSpectrochim Acta A Mol Biomol Spectrosc
December 2024
Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, Rua Marquês de São Vicente 225, Rio de Janeiro 22451-900, RJ, Brazil.
The effects of cosmic-ray bombardment of chiral molecules in the interstellar medium are simulated in the laboratory by performing radiolysis experiments of pure α-pinene ices at four different temperatures. The identification and significance of α-pinene have not been fully understood because of the insufficient amount of spectral information of these compounds at low temperatures. A comparison of the temperature dependence of the mid-infrared spectra of pure α-pinene ices before and after irradiation its irradiation by 61.
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