Radon emanation from construction materials has emerged as a dominant background to current and next generation dark matter searches, particularly those deploying noble liquid targets where radon progeny is expected to decay uniformly across fiducial volumes. Sensitivity studies show that radon activities of ~0.1uBq/kg must be achieved in order to probe the remaining parameter space accessible...
Radon emanated from detector materials and their decay daughters are potentially dangerous sources of rare event search experiments. In order to measure and control emanated radon for PandaX-4T detector, a radon emanation measurement system with electrostatic collection technique was designed. This system is consisting of a hemispherical copper counting chamber, a spiral cold trap and an...
The LEGEND collaboration is developing an experimental search for the neutrinoless double-beta ($0\nu\beta\beta$) decay of the isotope $^{76}$Ge. The first stage, LEGEND-200, is based on 200kg of $^{76}$Ge-enriched high-purity germanium detectors immersed in liquid argon. It is currently under construction at the Laboratori Nazionali del Gran Sasso in Italy.
Among others, novel inverted...
The Underground Laboratory of Modane (LSM, Laboratoire Souterrain de Modane) is the deepest European underground multidisciplinary platform. Under 4800 m.w.e ( Meter Water Equivalent), the LSM gives the opportunity to all experiments need to be sheltered from cosmic rays and/or looking for rare events to be hosted.
From Electronics, Biology, HPGe gamma spectrometry up to fundamental physic,...
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...
In rare event search experiments, activation of detector materials can lead to significant backgrounds. Typically, trace radioactive contaminants are activated by cosmic-ray interactions while the detector materials are being stored or transported above ground. In highly sensitive experiments, these cosmogenic backgrounds can limit sensitivity. It is therefore necessary to determine the...
The radon deposition is a critical background for many underground experimment through it's daughter 210Pb. Depending on the energy region the final background could be influenced by 210Pb,210Bi or 210Po. The energy emitted by the contaminated pieces is influence by the depth of implantation. In this work, I present a simulation of penetration depth. This depth is simulated by Geant 4 but is...
Neutrinoless double beta (0$\nu\beta\beta$) decay is a most compelling approach to determine the Majorana nature of neutrino and measure absolute value of neutrino mass. The LEGEND collaboration is aiming to look for a rare nuclear decay, ${}^{76}$Ge $\rightarrow$ ${}^{76}$Se + e$^-$ + e$^-$. Cosmologically induced isotope ${}^{42}$Ar and its decay progeny ${}^{42}$K in a liquid argon could...
Neutron-induced backgrounds are a key concern in low radioactivity experiments searching for rare events. One common source of neutrons is (α,n) reactions induced by α-particles from the radioactive isotopes present in detector materials. Since carbon-rich materials, such as plastic and epoxy, are often widely used in low-background experiments, 13C(α, n)16O could be a major source of...
The most discussed topic in direct search for dark matter is arguably the verification of the DAMA claim. In fact, the observed annual modulation of the signal rate in an array of NaI(Tl) detectors can be interpreted as the awaited signature of dark matter interaction. Several experimental groups are currently engaged in the attempt to verify such a game-changing claim in a model-independent...
Invented in the 1970s, High-Purity Germanium (HPGe) detection technology is still the reference for gamma-ray spectroscopy. Its excellent detection properties are unanimously recognized: in particular, its energy resolution performance is still unparalleled to this day. Despite its challenging operating conditions, HPGe detectors have become increasingly suitable for use in very diverse...
Neutrinoless double beta decay (0νββ) is a rare nuclear transition. If it is observed, it would answer open questions about neutrino masse and nature. To convert the 0νββ half-life into the neutrino Majorana mass a precise knowledge of the Nuclear Matrix Elements (NMEs) is required, but their current evaluation is strongly model-dependent. The measurement of highly suppressed β-decay spectral...
Experiments employing Xe and Ar as particle detectors often make use of heated zirconium getters to remove electronegative impurities from the gaseous phase. For low background experiments, a key design consideration is to choose a purifier model which is large enough to achieve adequate electronegative removal, but no larger than necessary to avoid excess radon emanation from the getter...
It is possible to increase sensitivity to low energy physics in a third or fourth DUNE-like module with better radiopurity measures and suitable modifications to a detector similar to the DUNE Far Detector design. In particular, sensitivity to supernova and solar neutrinos can be enhanced with improved MeV-scale reach. With a 136Xe doping in the liquid argon, the detector can also be used for...
HPGe detectors made of material enriched in Ge-76 were and are used by many experiments (Heidelberg-Moscow, IGEX, GERDA MAJORANA, LEGEND) for searches of neutrinoless double beta (0vbb) decay. Their main advantage is high detection efficiency (detector = source), high intrinsic radiopurity and excellent energy resolution. In order to achieve high discovery potential of the 0vbb decay, the...
A study was performed to look at the impact of varying the lower-level threshold settings of an ultra-low-background counting system’s (ULBCS) cosmic veto and the impact on background rates as seen by ultra-low-background proportional counters (ULBPC). The first ULBCS shield was constructed in the shallow underground laboratory at the Pacific Northwest National Laboratory (PNNL) over a decade...
Most underground laboratories (UL) were originally constructed for studies of fundamental physics, such as dark matter and neutrino-less double beta decay experiments. The fundamental physics experiments mentioned require ultra-sensitive detection at underground. Similarly, ultra-low background facility is invaluable for studies of radionuclides analysis from the perspective of reducing the...
Background Explorer is a toolkit for modeling backgrounds in sensitive detectors from radioactive sources. Originally developed for the SuperCDMS dark matter search, it is now open-source and freely available at https://github.com/bloer/bgexplorer. The components that make up the detector and shielding system, associated material assays of radioactive contamination levels, and radiation...
The nuclear isomer 180mTa has yet to have an observed decay as it has an expected half-life of over 1015 years—which is much longer than the current age of the Universe. The conditions necessary to detect such a rare event exist only in ultra-clean, radio-silent detectors, such as the MAJORANA DEMONSTRATOR. The uniqueness of this isomer arises from the nature of its stability: the isomeric...
The SuperCDMS SNOLAB experiment, currently under construction, will attempt to directly detect dark matter particles. Shielding surrounding the experiment’s detectors will
reduce interactions of particles from radioactivity and cosmic rays. A gas purge will remove radon from gaps in the shielding to reduce backgrounds further. Gaskets used to seal
this purge volume must allow sufficiently...
Expected backgrounds for electrostatic PIN-diode radon-emanation systems consist of three basic terms: a grow-in term, due to radon emanating from the detection chamber itself; a decaying term, due to radon that is transferred into the chamber along with radon from the sample; and a term constant in time due to environmental backgrounds such as cosmic rays. The first two backgrounds should...
