Acrylic is widely used in low background experiments such as underground neutrino experiments and dark matter experiments around the world for its good transmittance, low radioactive background and good chemical compatibility with water and liquid scintillator. Jiangmen underground neutrino oscillation experiment (JUNO) has a 35.4 meters diameter 566-ton acrylic sphere shell for holding liquid...
The search for neutrinoless double beta decay could cast light on one critical piece missing in our knowledge i.e. the nature of the neutrino mass. Its observation is indeed the most sensitive experimental way to prove that neutrino is a Majorana particle. The observation of such a potentially rare process demands a detector with an excellent energy resolution, an extremely low radioactivity...
For many current detectors aimed at rare-event searches, radon is a dominating source of background. These experiments can strongly benefit from the reduction of ${}^{222}\mathrm{Rn}$ that is released by metallic surfaces within the setup. A new radon mitigation strategy employing thin surface coatings has been studied and significant reduction factors of the ${}^{220}\mathrm{Rn}$ and...
SABRE (Sodium Iodide with Active Background Rejection) is a new project to search for the annually modulating signal expected from Dark Matter (DM), using an array of ultra-pure NaI(Tl) detectors surrounded by an active scintillator veto to further reduce the intrinsic and external background.
The first phase of the experiment is the SABRE Proof of Principle (PoP), a single 5-kg crystal...
The COSINUS (Cryogenic Observatory for SIgnatures seen in Next-generation Underground Searches) project is in the final planning phase of building up the experiment at an underground site.
Crystals made of NaI will be operated as cryogenic detectors to search for DM-nucleus scattering with the aim of probing the long-standing results of the DAMA/LIBRA collaboration. Operating the detectors at...
For more than three decades UK astrophysicists have been operating experiments to search for Dark Matter 1100m below ground in a purpose-built 'low-background' facilities at Boulby mine in the North East of England. This facility - the Boulby Underground Laboratory - is one of just a few places in the world suited to hosting these and other science projects requiring a 'quiet environment',...
Superconducting circuits are emerging as leading candidates in the development of Quantum Bits (qubits). Their main limit with respect to the other technologies resides in the poor coherence time, i.e. the time in which they retain a quantum behaviour. The DEMETRA project proposes environmental radioactivity as one of the sources of decoherence: interactions in the substrates on which the...
Determination of 210Po in metals and electronic components down to 0.5 mBq/kg
T. Mróz, P. Czudak, M. Wojcik, G. Zuzel
Institute of Physics, Jagiellonian University, Krakow, Poland
The bottom part of the 238U chain, containing 210Pb, 210Bi and 210Po is difficult to detect. 210Pb emits low energy betas and a weak gamma (46.4 keV) with relatively low probability thus, gamma ray spectrometers...
In nuclear and particle physics experiments, reduction of radioactive intrinsic background is one of the keys for the success of the experiments. In many cases the radioactive background generated from decay products of radio nuclides such as $^{232}$Th, $^{238}$U and $^{40}$K could exactly overlap the observable energy regions of interest.
In this context it is crucial to develop...
In the current state of rare-event searches, an increase in target mass is necessary to improve the experiments sensitivity. This will be the case of the multi-ton liquid xenon DARWIN detector aiming at the direct detection of dark matter as well as studying neutrino physics. Even if very low background levels have already been achieved in such detectors, further control and reduction are both...
The 13C(a,n)16O reaction is very important in astrophysical context. This reaction is the dominant neutron source for the synthesis of the main s-process component of heavy elements in thermally pulsing, low-mass AGB stars. The stellar temperature of s process in AGB translates to a Gamow window between 140 - 230 keV, far below the Coulomb barrier.
Various measurements of the low energy cross...
The next generation low-background detectors operating deep underground aim for unprecedented low levels of radioactive backgrounds. The deposition and presence of radon progeny on detector surfaces and surrounding materials is an added source of energetic background events.
In addition to limiting the detector material's radon exposure to reduce potential surface backgrounds, it is just as...
The Neutrino Experiment with a Xenon TPC (NEXT) searches for the neutrinoless double beta decay of $^{136}$Xe using a high pressure xenon gas time projection chamber. This detector technology has several key advantages, including excellent energy resolution, powerful event classification based on track topology, and favorable mass scalability. The rareness of the decay demands low-background...
The MAJORANA Collaboration is searching for neutrinoless double-beta decay in Ge-76 with an array of p-type, point-contact Ge detectors. The MAJORANA DEMONSTRATOR is comprised of 44 kg (30 kg enriched in Ge-76) of Ge detectors split between two modules contained in a low background passive and active shield at the Sanford Underground Research Facility in Lead, South Dakota. Our latest results...
The DarkSide-50 dark matter search experiment demonstrated that argon derived from underground can be highly reduced in $^{39}$Ar, and since then the demand for this commodity has risen. Several fundamental physics experiments need argon that is reduced in $^{39}$Ar as well as $^{42}$Ar, and there are needs in other scientific fields as well (e.g., age-dating). With the increased needs for...
The DAMIC (Dark Matter in CCDs) experiment employs the bulk silicon of scientific-grade charge coupled devices (CCDs) to detect Dark Matter particles. DAMIC-100, a 41 g detector, is operating in the SNOLAB laboratory, located 2 km below the surface within the Vale Creighton Mine near Sudbury, Ontario, Canada. We present a powerful technique to distinguish and reject background events....
The new shallow-underground laboratory Felsenkeller (140\,m.w.e.) in Dresden, Germany hosts a new 5\,MV underground ion accelerator in tunnels VIII and IX, as well as a low-radioactivity counting facility. For the laboratory commissioning both the muon and neutron background were measured and matched by Monte Carlo simulations.
A portable muon detector based on the close cathode chamber...
Neutron-induced background may cause problems for many underground experiments looking for rare events. A number of computer codes are available to calculate cross-sections of (alpha,n) reactions, excitation functions and neutron yields. We have used EMPIRE2.19/3.3 and TALYS1.9 to calculate neutron production cross-sections and excitation functions, and modified SOURCES4 to evaluate neutron...
There are two major underground experiments in Korea, AMoRE and COSINE, searching for neutrinoless double beta decay and WIMP (Weakly Interacting Massive Particle) type dark matter respectively. The Advanced Molybdenum based Rare process Experiment (AMoRE) is searching for the neutrinoless double beta decay of 100Mo isotopes in molybdate crystals using high-resolution cryogenic detectors in...
Removal of long-lived Rn-222 daughters from metal surfaces
Surface contamination with long-lived daughters of Rn-222 is of great interest for experiments looking for rare events. These include the detection of low energy solar neutrinos, searches for neutrino-less double beta decay or searches or dark matter. Decays of Pb-210, Bi-210 and
finally Po-210 may contribute significantly to the...
The DEAP-3600 Collaboration recently released results describing an ultra-low background search
for non-baryonic dark matter at SNOLAB, reaching a sensitivity of $3.9\times 10^{-45}\;\mbox{cm}^2$
for a 100 GeV/c$^2$ WIMP mass. A background model was constructed, tuned on the sidebands,
used to inform data-selection cuts, and used to predict rates in the region of interest for
WIMP...
GERDA (GErmanium Detector Array) situated in the Laboratori Nazionali del Gran Sasso (LNGS) of INFN searches for the lepton-number violating neutrinoless double beta ($0\nu\beta\beta$) decay of $^{76}$Ge. Bare high-purity germanium (HPGe) detectors enriched in the double beta decay isotope $^{76}$Ge are deployed in liquid argon (LAr). Background discrimination is achieved both by analyzing the...
SNO+ water purification and radium and radon assay techniques
Autor: Nasim Fatemighomi, SNOLAB
The SNO+ cavity is currently filled with 7400 tonnes of ultra pure water. The water purification system was developed for the SNO experiment prior to SNO+ and is now fully recommissioned and used to refill the SNO+ cavity and acrylic vessel. The water from Creighton mine is purified by going...
Recently, the DAMA/LIBRA collaboration confirmed observation of a modulated signal consistent with the DM hypothesis at a 13σ level. However, independent observation of the signal at another location and verification of its connection to the DM scattering off atoms are required. For that purpose, we created underground laboratory at the Kamioka mine and specialized laboratory for crystal...
Studies of poly(ethylene naphthalate) for use as a structural scintillator in low background experiments
Poly(ethylene naphthalate), PEN, has been observed to scintillate in the blue wavelength region, without the need for additional materials.
Combined with measurements of a high intrinsic radiopurity, this has sparked interest in the material for use in low-background experiments.
This...
The intrinsic radioactive contamination of detector components and surrounding materials is typically the most relevant and limiting source of background for experiments studying rare events, such as those searching for direct evidence of dark matter or neutrinoless double beta decay. Primordial radionuclides Th-232 and U-238 and their daughters, as well as K-40 are of primary concern. Based...
We have studied on surface and bulk Pb210/Po210 contamination
on copper and PTFE using low background alpha counter. Copper and PTFE
are the material used in various low background underground experiments
such as dark matter search and neutrino double beta decay search.
It is important to know the Pb210/Po210 contamination in copper and PTFE.
At the last LRT workshop, we reported that we had...
The ANDES (Agua Negra Deep Experiment Site) project aims at the construction of an underground laboratory between Argentina and Chili, taking advantage of the construction of the Agua Negra Tunnel between the two countries. After a pre-feasibility study in 2005, the final project for the construction of the road tunnel was approved and the international tender started in 2013.
The ANDES...
The PandaX-4T dark matter experiment will utilize a two-phase liquid/gas xenon time projection chamber containing 4 tonnes of liquid xenon. The PandaX-4T detector will be located at the Jinping Underground laboratory with 2400m overburden in Sichuan, China. Multiple low background techniques are used to assay and screen materials and parts to control the intrinsic/surface backgrounds. Also...
GeMSE (Germanium Material and Meteorite Screening Experiment) is a large-volume gamma-ray spectrometer devoted to the screening of meteorite samples and the selection of materials for rare-event search experiments. Located underground at 620 m.w.e. and featuring a multi-layer shielding, its current background level is below 240 counts/day in the 100 - 2700 keV range.
GeMSE is an ideal...
The most modern mechanical technologies and cutting edge radio-analytical techniques merged for extremely low background achievement
S.Nisi1, D. Orlandi1
1National Institute of Nuclear Physics, Gran Sasso National Laboratory, 67100 Assergi (AQ), Italy
The sensitivity of the experiments, searching for rare and low energy processes which could explain the most fascinating open questions...
Rare event detection experiments, such as direct dark matter and neutrino-less double beta decay searches, pose stringent limits on the experimental backgrounds in order to achieve the required sensitivities to discover new physics. The backgrounds introduced by radioisotopes in the detector construction materials must be carefully considered. Thanks to having no long-lived radioisotopes and...
In the last years, liquid xenon detectors became very popular in the field of low energy rare-event search. With the increasing size of the detectors, external radiation is no longer the dominant background source in the latest generation of experiments. Instead, the achievable radio-purity is limited by internal contamination due to radioactive noble gas impurities, in particular 85Kr and...
The XENON1T detector is a dual-phase time projection chamber devoted to dark matter searches through their scattering off xenon atoms in a 2 tonne liquid xenon target. The background rate in the central volume of the XENON1T detector is the lowest achieved so far with a liquid xenon-based direct detection experiment. In this talk I describe the response model of the detector, the challenges of...
