Design and Characterization of a Neutron Calibration Facility for the Study of sub-keV Nuclear Recoils

As part of an experimental effort to demonstrate sensitivity in a large-mass detector to the ultra-low energy recoils expected from coherent neutrino-nucleus elastic scattering, we have designed and built a highly monochromatic 24 keV neutron beam at the Kansas State University Triga Mark-II reactor. The beam characteristics were chosen so as to mimic the soft recoil energies expected from reactor antineutrinos in a variety of targets, allowing to understand the response of dedicated detector technologies in this yet unexplored sub-keV recoil range. A full characterization of the beam properties (intensity, monochromaticity, contaminations, beam profile) is presented, together with first tests of the calibration setup using proton recoils in organic scintillator.Comment: submitted to Nucl. Instr. Meth.

Beryllium-7 analyses in seawater by low background gamma-spectroscopy

Author Posting. © Akadémiai Kiadó, 2008. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Journal of Radioanalytical and Nuclear Chemistry 277 (2008): 253-259, doi:10.1007/s10967-008-0739-y.7Be is a cosmogenic isotope produced in the stratosphere and troposphere. 7Be has a half-life of 53.4 days and decays to 7Li emitting a 477 keV gamma line with a branching ratio of 0.104. It is predominantly washed out of the atmosphere through wet deposition. It is a tool for oceanographers to study air sea interaction and water mass mixing. Beryllium’s largely non-reactive nature in the open ocean makes it an excellent conservative tracer. Its conservative nature and extreme dilution in seawater also makes it difficult to concentrate and analyze. Early experiments at WHOI with Fe(OH)3 cartridges to directly collect 7Be by insitu underwater pumps proved ineffective. Collection efficiencies of the cartridges were too low to be consistently useful. At sea chemistry of whole water samples became the method of choice. The use of stable 9Be as a yield monitor further improved the accuracy of the procedure. The method was optimized at WHOI in 2005 using a seawater line that enters WHOI’s coastal research lab. The procedure was then used on an oceanographic cruise on the R/V Oceanus out of Bermuda in the oligotrophic Sargasso Sea.The authors would like to thank DOE, ONR and NSF for funding of this research

Feasibility of low energy radiative capture experiments at the LUNA underground accelerator facility

The LUNA (Laboratory Underground for Nuclear Astrophysics) facility has been designed to study nuclear reactions of astrophysical interest. It is located deep underground in the Gran Sasso National Laboratory, Italy. Two electrostatic accelerators, with 50 and 400 kV maximum voltage, in combination with solid and gas target setups allowed to measure the total cross sections of the radiative capture reactions $^2$H(p,$\gamma$)3He and $^{14}$N(p,$\gamma$)$^{15}$O within their relevant Gamow peaks. We report on the gamma background in the Gran Sasso laboratory measured by germanium and bismuth germanate detectors, with and without an incident proton beam. A method to localize the sources of beam induced background using the Doppler shift of emitted gamma rays is presented. The feasibility of radiative capture studies at energies of astrophysical interest is discussed for several experimental scenarios.Comment: Submitted to Eur. Phys. J.

The Borexino detector at the Laboratori Nazionali del Gran Sasso

Borexino, a large volume detector for low energy neutrino spectroscopy, is currently running underground at the Laboratori Nazionali del Gran Sasso, Italy. The main goal of the experiment is the real-time measurement of sub MeV solar neutrinos, and particularly of the mono energetic (862 keV) Be7 electron capture neutrinos, via neutrino-electron scattering in an ultra-pure liquid scintillator. This paper is mostly devoted to the description of the detector structure, the photomultipliers, the electronics, and the trigger and calibration systems. The real performance of the detector, which always meets, and sometimes exceeds, design expectations, is also shown. Some important aspects of the Borexino project, i.e. the fluid handling plants, the purification techniques and the filling procedures, are not covered in this paper and are, or will be, published elsewhere (see Introduction and Bibliography).Comment: 37 pages, 43 figures, to be submitted to NI

A Low-Energy HPGe Detector Dedicated to Radioactivity Measurements Far Below the Environmental Levels

Successive background reduction factors of a low-background high-purity semi-planar Germanium detection system, N type, were achieved with various shielding conditions, at ground level and underground locations. The optimal working conditions, achieved at a depth of 500 m water equivalent (m w.e.) lead to a background reduction factor of about 100 in the energy region from 5 to 1000 keV in comparison with a measurement at sea level. The integral count rate as low as (0.00361 +/- 0.00004) s-1 over this energy interval is mainly attributable to the influence of the cosmic rays but also to the residuals of the natural decay chains inside the various constituents of the detection system, the radon and progenies from the environment, the weak level of man-made radionuclides and finally the cosmogenic activation of the shielding materials formerly stored at sea level. About one event per day, or less, corresponding to the the -rays of interest, are recorded in energy intervals of four times the FWHM resolution of the detector. Detection limits were deduced for 210Pb and uranium metal activities and for a few radionuclides of interest. Materials studied are: clay standard, uranium metal, biological matrix exposed to radon flux; gold and silver foils, various lead and copper batches, as a contribution to material selection with respect to their low level of radiocontaminants, in particular for the solar neutrino and dark matter experiment BOREXINO.JRC.DG.D-Institute for Reference Materials and Measurements (Geel

An Active Background Discrimination Technique Using a Multiple Detector Event by Event Recording System.

Abstract not availableJRC.D-Institute for Reference Materials and Measurements (Geel