scholarly journals Identification of new isomers in $$^{228}$$Ac: impact on dark matter searches

2021 ◽  
Vol 81 (8) ◽  
Author(s):  
K. W. Kim ◽  
G. Adhikari ◽  
E. Barbosa de Souza ◽  
N. Carlin ◽  
J. J. Choi ◽  
...  

AbstractWe report the identification of metastable isomeric states of $$^{228}$$ 228 Ac at 6.28 keV, 6.67 keV and 20.19 keV, with lifetimes of an order of 100 ns. These states are produced by the $$\beta $$ β -decay of $$^{228}$$ 228 Ra, a component of the $$^{232}$$ 232 Th decay chain, with $$\beta $$ β Q-values of 39.52 keV, 39.13 keV and 25.61 keV, respectively. Due to the low Q-value of $$^{228}$$ 228 Ra as well as the relative abundance of $$^{232}$$ 232 Th and their progeny in low background experiments, these observations potentially impact the low-energy background modeling of dark matter search experiments.

2016 ◽  
Author(s):  
Philip Von Doetinchem ◽  
Tsuguo Aramaki ◽  
Steven Boggs ◽  
Hideyuki Fuke ◽  
Charles Hailey ◽  
...  

2014 ◽  
Vol 29 (19) ◽  
pp. 1443010 ◽  
Author(s):  
C. Cuesta ◽  
J. Amaré ◽  
S. Cebrián ◽  
E. García ◽  
C. Ginestra ◽  
...  

NaI(Tl) large crystals are applied in the search for galactic dark matter particles through their elastic scattering off the target nuclei in the detector by measuring the scintillation signal produced. However, energies deposited in the form of nuclear recoils are small, which added to the low efficiency to convert that energy into scintillation, makes that events at or very near the energy threshold, attributed either to radioactive backgrounds or to spurious noise (nonbulk NaI(Tl) scintillation events), can compromise the sensitivity goals of such an experiment. DAMA/LIBRA experiment, using 250 kg NaI(Tl) target, reported first evidence of the presence of an annual modulation in the detection rate compatible with that expected for a dark matter signal just in the region below 6 keVee (electron equivalent energy). In the frame of the ANAIS (Annual modulation with NaI Scintillators) dark matter search project a large and long effort has been carried out in order to understand the origin of events at very low energy in large sodium iodide detectors and develop convenient filters to reject those nonattributable to scintillation in the bulk NaI(Tl) crystal. 40K is probably the most relevant radioactive contaminant in the bulk for NaI(Tl) detectors because of its important contribution to the background at very low energy. ANAIS goal is to achieve levels at or below 20 ppb natural potassium. In this paper we will report on our effort to determine the 40K contamination in several NaI(Tl) crystals, by measuring in coincidence between two (or more) of them. Results obtained for the 40K content of crystals from different providers will be compared and prospects of the ANAIS dark matter search experiment will be briefly reviewed.


Author(s):  
Tomonori Ikeda ◽  
Kiseki Nakamura ◽  
Takuya Shimada ◽  
Ryota Yakabe ◽  
Takashi Hashimoto ◽  
...  

Abstract NEWAGE is a direction-sensitive dark matter search using a low-pressure gaseous time projection chamber. A low alpha-ray emission rate micro pixel chamber had been developed in order to reduce background for dark matter search. We conducted the dark matter search at the Kamioka Observatory in 2018. The total live time was 107.6 days corresponding to an exposure of 1.1 kg⋅days. Two events remained in the energy region of 50-60 keV which was consistent with 2.5 events of the expected background. A directional analysis was carried out and no significant forward-backward asymmetry derived from the WIMP-nucleus elastic scatterings was found. Thus a 90% confidence level upper limit on Spin-Dependent WIMP-proton cross section of 50 pb for a WIMP mass of 100 GeV/c2 was derived. This limit is the most stringent yet obtained from direction-sensitive dark matter search experiments.


2013 ◽  
Vol 8 (3) ◽  
pp. 27-38
Author(s):  
Aleksandr Bondar ◽  
Alexey Buzulutskov ◽  
Aleksandr Burdakov ◽  
Evgeny Grishnyaev ◽  
Aleksandr Dolgov ◽  
...  

The proposal of two neutron scattering systems for calibration of two-phase cryogenic avalanche detectors with high sensitivity being developed at Budker INP is presented. This kind of detectors is designed for the search of dark matter and low energy neutrino detection, in particular, coherent neutrino scattering on nuclei. Detector calibration is made with a measurement of ionization yield and scintillation quenching factor for low energy recoiling nuclei (in 0.5 to 100 keV range) originating from elastic scattering of neutrons. To provide wide range of recoiling nuclei energies two systems of neutron scattering are proposed. The first one is based on small-sized DD generator of fast (2.45 MeV) monoenergetic neutrons operating on sealed neutron tube. The second one is based on tandem proton accelerator and lithium target and capable of generation of monoenergetic epithermal neutrons with energy up to 100 keV


2017 ◽  
Vol 12 (03) ◽  
pp. C03009-C03009 ◽  
Author(s):  
M. Bondí ◽  
M. Battaglieri ◽  
M. Carpinelli ◽  
A. Celentano ◽  
M. De Napoli ◽  
...  

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
C. E. Aalseth ◽  
P. Agnes ◽  
A. Alton ◽  
K. Arisaka ◽  
D. M. Asner ◽  
...  

Although the existence of dark matter is supported by many evidences, based on astrophysical measurements, its nature is still completely unknown. One major candidate is represented by weakly interacting massive particles (WIMPs), which could in principle be detected through their collisions with ordinary nuclei in a sensitive target, producing observable low-energy (<100 keV) nuclear recoils. The DarkSide program aims at the WIPMs detection using a liquid argon time projection chamber (LAr-TPC). In this paper we quickly review the DarkSide program focusing in particular on the next generation experiment DarkSide-G2, a 3.6-ton LAr-TPC. The different detector components are described as well as the improvements needed to scale the detector from DarkSide-50 (50 kg LAr-TPC) up to DarkSide-G2. Finally, the preliminary results on background suppression and expected sensitivity are presented.


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