XEMIS2: A liquid xenon detector for small animal medical imaging Gallego Manzano, L.; Abaline, J.M.; Acounis, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2018, Volume:
912
Journal Article
Peer reviewed
Open access
We report a new liquid xenon Compton camera, called XEMIS2 (XEnon Medical Imaging System), developed to image for the first time small animals using 3γ imaging. This technique proposes an alternative ...to reduce the administered radiopharmaceutical activity while preserving diagnostic image quality using liquid xenon as detection medium. Given the success of its predecessor, a small dimension liquid xenon time projection chamber called XEMIS1, we are currently building a larger scale detector for preclinical applications. This second prototype, XEMIS2, is a single phase liquid xenon cylindrical camera with a large axial field of view for full-body small animal imaging. XEMIS2 holds around 200 kg of xenon and it has been designed to enable high-efficiency and simultaneous detection of the three γ-rays emitted by a 44Sc radionuclide. The innovative geometry of XEMIS2 will allow to discriminate and measure the position and deposited energy of most Compton interactions inside the detector. In order to manage such a large quantity of xenon, an innovative high-pressure subsystem known as ReStoX has been developed and successfully qualified. ReStoX allows to maintain the xenon in liquid state at the desired temperature and pressure, transfer the xenon into XEMIS2 and store it during long term periods. XEMIS2 will be installed at a non controlled radioactive area of Nantes Hospital. The goal is to evaluate image quality of a 20 min whole-body preclinical exam with an injected activity of 20 kBq.
•The first 3 gamma whole-body small animal scanner is presented.•The XEMIS2 camera is a single-phase liquid xenon detector with a 24 cm axial field of view.•A dedicated 32-channels low power circuit called XTRACT is described.•ReStoX is an advanced cryogenic system developed to liquefy, recover and store the xenon.•A reconstructed image using the innovative 3 gamma reconstruction algorithm is reported.
We present the first constraints on the spin-dependent, inelastic scattering cross section of weakly interacting massive particles (WIMPs) on nucleons from XENON100 data with an exposure of 7.64×103 ...kg·days. XENON100 is a dual-phase xenon time projection chamber with 62 kg of active mass, operated at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy and designed to search for nuclear recoils from WIMP-nucleus interactions. Here we explore inelastic scattering, where a transition to a low-lying excited nuclear state of Xe129 is induced. The experimental signature is a nuclear recoil observed together with the prompt deexcitation photon. We see no evidence for such inelastic WIMP-Xe129 interactions. A profile likelihood analysis allows us to set a 90% C.L. upper limit on the inelastic, spin-dependent WIMP-nucleon cross section of 3.3×10−38 cm2 at 100 GeV/c2. This is the most constraining result to date, and sets the pathway for an analysis of this interaction channel in upcoming, larger dual-phase xenon detectors.
Abstract We correct an overestimation of the production rate of $$^{137}$$ 137 Xe in the DARWIN detector operated at LNGS. This formerly dominant intrinsic background source is now at a level similar ...to the irreducible background from solar $$^8$$ 8 B neutrinos, thus unproblematic at the LNGS depth. The projected half-life sensitivity for the neutrinoless double beta decay ( $$0\nu \beta \beta $$ 0 ν β β ) of $$^{136}$$ 136 Xe improves by $$22\%$$ 22 % compared to the previously reported number and is now $$T^{0\nu }_{1/2}= {3.0\times 10^{27}} \hbox { yr}$$ T 1 / 2 0 ν = 3.0 × 10 27 yr (90% C.L.) after 10 years of DARWIN operation.
In this work, we expand on the XENON1T nuclear recoil searches to study the individual signals of dark matter interactions from operators up to dimension eight in a chiral effective field theory ...(ChEFT) and a model of inelastic dark matter (iDM). We analyze data from two science runs of the XENON1T detector totaling 1 t × yr exposure. For these analyses, we extended the region of interest from 4.9 , 40.9 keV NR to 4.9 , 54.4 keV NR to enhance our sensitivity for signals that peak at nonzero energies. We show that the data are consistent with the background-only hypothesis, with a small background overfluctuation observed peaking between 20 and 50 keV NR , resulting in a maximum local discovery significance of 1.7 σ for the Vector ⊗ Vector strange ChEFT channel for a dark matter particle of 70 GeV / c 2 and 1.8 σ for an iDM particle of 50 GeV / c 2 with a mass splitting of 100 keV / c 2 . For each model, we report 90% confidence level upper limits. We also report upper limits on three benchmark models of dark matter interaction using ChEFT where we investigate the effect of isospin-breaking interactions. We observe rate-driven cancellations in regions of the isospin-breaking couplings, leading to up to 6 orders of magnitude weaker upper limits with respect to the isospin-conserving case. Published by the American Physical Society 2024
This paper details the first application of a software tagging algorithm to reduce radon-induced backgrounds in liquid noble element time projection chambers, such as XENON1T and XENONnT. The ...convection velocity field in XENON1T was mapped out using Rn 222 and Po 218 events, and the rms convection speed was measured to be 0.30 ± 0.01 cm / s . Given this velocity field, Pb 214 background events can be tagged when they are followed by Bi 214 and Po 214 decays, or preceded by Po 218 decays. This was achieved by evolving a point cloud in the direction of a measured convection velocity field, and searching for Bi 214 and Po 214 decays or Po 218 decays within a volume defined by the point cloud. In XENON1T, this tagging system achieved a Pb 214 background reduction of 6.2 − 0.9 + 0.4 % with an exposure loss of 1.8 ± 0.2 % , despite the timescales of convection being smaller than the relevant decay times. We show that the performance can be improved in XENONnT, and that the performance of such a software-tagging approach can be expected to be further improved in a diffusion-limited scenario. Finally, a similar method might be useful to tag the cosmogenic Xe 137 background, which is relevant to the search for neutrinoless double-beta decay. Published by the American Physical Society 2024
The measurements foreseen in the COMPASS experiment at CERN, require high resolution tracking detectors, with low radiation length and high rate capability. For this purpose we have developed and ...optimized a gaseous microstrip detector ‘Micromegas’. Twelve planes with 1024 strips each, assembled in 3 stations of 4 views XYUV, have been operated with success in the summer of 2002 in the COMPASS environment. We describe here the performances and results obtained.
We describe the purification of xenon from traces of the radioactive noble gas radon using a cryogenic distillation column. The distillation column was integrated into the gas purification loop of ...the XENON100 detector for online radon removal. This enabled us to significantly reduce the constant Rn-222 background originating from radon emanation. After inserting an auxiliary 222Rn emanation source in the gas loop, we determined a radon reduction factor of R > 27 (95% C.L.) for the distillation column by monitoring the Rn-222 activity concentration inside the XENON100 detector.
A low-energy electronic recoil calibration of XENON1T, a dual-phase xenon time projection chamber, with an internal 37Ar source was performed. This calibration source features a 35-day half-life and ...provides two mono-energetic lines at 2.82 keV and 0.27 keV. The photon yield and electron yield at 2.82 keV are measured to be (32.3±0.3) photons/keV and (40.6±0.5) electrons/keV, respectively, in agreement with other measurements and with NEST predictions. The electron yield at 0.27 keV is also measured and it is (68.0+6.3−3.7) electrons/keV. The 37Ar calibration confirms that the detector is well-understood in the energy region close to the detection threshold, with the 2.82 keV line reconstructed at (2.83±0.02) keV, which further validates the model used to interpret the low-energy electronic recoil excess previously reported by XENON1T. The ability to efficiently remove argon with cryogenic distillation after the calibration proves that 37Ar can be considered as a regular calibration source for multi-tonne xenon detectors.
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