Underground argon (UAr) with lower cosmogenic activities of $^{39}Ar$ and $^{42}Ar$ has been planned as a detector in detecting scintillation light and charge collection using time projection chambers for dark matter searches and as a veto detector in suppressing backgrounds for neutrinoless double beta decay (0$νββ$) experiments. Long-lived radioactive isotopes, $^{39}Ar$ and $^{42}Ar$, can also be produced on the surface when UAr is pumped out from a deep well. Understanding the production of long-lived isotopes in Ar is important for utilizing UAr for dark matter and 0$νββ$ experiments in terms of its production, transportation, and storage. Ar exposure to cosmic rays at sea-level is simulated using Geant4 for a given cosmic ray muon, neutron, and proton energy spectrum. We report the simulated cosmogenic production rates of $^{39}Ar$, $^{42}Ar$, and other long-lived isotopes at sea-level from fast neutrons, high energy muons, and high energy protons. Total production rates of 938.53/kg$_{Ar}\cdot$day and 5.81$\times$10$^{-3}$/kg$_{Ar}\cdot$day for $^{39}$Ar and $^{42}$Ar are found from our simulation. Utilizing these production rates, we set a time limit of 954 days constrained by the production of $^{39}$Ar for UAr to be on the surface before it compromises the sensitivity for a dark matter experiment. Similarly, a time limit of 1702 days constrained by the production of $^{42}$Ar is found for a 0$νββ$ experiment.
We perform simulation study for a 10-kg $^{100}$Mo-based bolometeric demonstration experiment for neutrinoless double-beta decay ($0νββ$) search at China JinPing underground Laboratory (CJPL). Cosmogenic production of radionuclides in $^{100}$Mo-enriched lithium molybdate crystals and copper components of the detector system are studied using Geant4 toolkit based on the simulated cosmic ray data from the CRY library. Background energy spectra of the cosmogenic radionuclides including $^{56}$Co, $^{82}$Rb and $^{88}$Y which are harmful for the $^{100}$Mo-based $0νββ$ experiment are investigated…
The discovery of argon from underground sources with significantly less 39Ar than atmospheric argon was an important step in the development of direct-detection dark matter experiments using argon as the active target. We report on the design and operation of a low background detector with a single phase liquid argon target that was built to study the 39Ar content of the underground argon. Underground argon from the Kinder Morgan CO2 plant in Cortez, Colorado was determined to have less than 0.65% of the 39Ar activity in atmospheric argon.
Neutrons produced by cosmic muon interactions are important contributors to backgrounds in underground detectors when searching for rare events. Typically such neutrons can dominate the background, as they are particularly difficult to shield and detect. Since actual data is sparse and not well documented, simulation studies must be used to design shields and predict background rates. Thus validation of any simulation code is necessary to assure reliable results. This work compares in detail the predictions of the FLUKA simulation code to existing data, and uses this code to report a simulatio…
130Te is one of the candidates for the search for neutrinoless double beta decay. It is currently planned to be used in two experiments: CUORE and SNO+. In the CUORE experiment TeO2 crystals cooled at cryogenic temperatures will be used. In the SNO+ experiment natTe will be deployed up to 0.3% loading in the liquid scintillator volume. A possible background for the signal searched for, are the high Q-value, long-lived isotopes, produced by cosmogenic neutron and proton spallation reaction on the target material. A total of 18 isotopes with Q-value larger than 2 MeV and T1/2 >20 days have been …
The DarkSide-50 experiment demonstrated the ability to extract and purify argon from deep underground sources and showed that the concentration of $^{39}$Ar in that argon was greatly reduced from the level found in argon derived from the atmosphere. That discovery broadened the physics reach of argon-based detector and created a demand for low-radioactivity underground argon (UAr) in high-energy physics, nuclear physics, and in environmental and allied sciences. The Global Argon Dark Matter Collaboration (GADMC) is preparing to produce UAr for DarkSide-20k, but a general UAr supply for the com…
DarkSide-20k (DS-20k) will exploit the physical and chemical properties of liquid argon housed within a large dual-phase time project chamber (TPC) in its direct search for dark matter. The TPC will utilize a compact, integrated design with many novel features to enable the \SI{20}{t} fiducial volume of underground argon. Underground Argon (UAr) is sourced from underground CO$_2$ wells and depleted in the radioactive isotope $^{39}$Ar, greatly enhancing the experimental sensitivity to dark matter interactions. Sourcing and transporting the $\mathcal{O}$(\SI{100}{t}) of UAr for DS-20k is costly…
Double beta decay is a very rare nuclear process and, therefore, experiments intended to detect it must be operated deep underground and in ultra-low background conditions. Long-lived radioisotopes produced by the previous exposure of materials to cosmic rays on the Earth's surface or even underground can become problematic for the required sensitivity. Here, the studies developed to quantify and reduce the activation yields in detectors and materials used in the set-up of these experiments will be reviewed, considering target materials like germanium, tellurium and xenon together with other o…
The parameters of the seasonal modulations (variations) in the intensity of muons and cosmogenic neutrons generated by them at a mean muon energy of 280 GeV have been determined in the LVD (Large Volume Detector) experiment. The modulations of muons and neutrons are caused by a temperature effect, the seasonal temperature and density variations of the upper atmospheric layers. The analysis performed here leads to the conclusion that the variations in the mean energy of the muon flux are the main source of underground cosmogenic neutron variations, because the energy of muons is more sensitive …
The rare event search experiments using germanium detectors are performed in the underground laboratories to prevent cosmic rays. However, the cosmogenic activation of the cupreous detector components on the ground will generate long half-life radioisotopes and contribute continually to the expected background level. We present a study on the cosmogenic activation of copper after 504 days of exposure at an altitude of 2469.4 m outside the China Jinping Underground Laboratory (CJPL). The specific activities of the cosmogenic nuclides produced in the copper bricks were measured using a low backg…
Measurement of the $^{39}$Ar specific activity in atmospheric argon with DArT at the Canfranc Underground Laboratory
INFN Cagliari（意大利核物理研究所卡利亚里分部）；Physics Department, Università degli Studi di Cagliari（卡利亚里大学物理系）；CIEMAT, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas（能源、环境和技术研究中央中心）；Savannah River National Laboratory（萨凡纳河国家实验室）；Centro de Astropartículas y Física de Altas Energías (CAPA), Universidad de Zaragoza（萨拉戈萨大学高能天体粒子与物理学中心）；INFN Laboratori Nazionali del Gran Sasso（意大利核物理研究所格兰萨索国家实验室）；Department of Physics, University of California, Davis（加州大学戴维斯分校物理系）；University of Oxford（牛津大学）；Department of Physics, Carleton University（卡尔顿大学物理系）；AstroCeNT, Nicolaus Copernicus Astronomical Center of the Polish（波兰科学院尼古拉·哥白尼天文学中心）
The cosmogenic production of long-lived radioactive isotopes in materials is an hazard for experiments demanding ultra-low background conditions. Although NaI(Tl) scintillators have been used in this context for a long time, very few activation data were available. We present results from two 12.5 kg NaI(Tl) detectors, developed within the ANAIS project and installed at the Canfranc Underground Laboratory. The prompt data taking starting made possible a reliable quantification of production of some I, Te and Na isotopes with half-lives larger than ten days. Initial activities underground were …
We have experimentally determined the production rate of $^{39}$Ar and $^{37}$Ar from cosmic ray neutron interactions in argon at sea level. Understanding these production rates is important for argon-based dark matter experiments that plan to utilize argon extracted from deep underground because it is imperative to know what the ingrowth of $^{39}$Ar will be during the production, transport, and storage of the underground argon. These measurements also allow for the prediction of $^{39}$Ar and $^{37}$Ar concentrations in the atmosphere which can be used to determine the presence of other sour…
Experiments looking for rare events like the direct detection of dark matter particles, neutrino interactions or the nuclear double beta decay are operated deep underground to suppress the effect of cosmic rays. But the production of radioactive isotopes in materials due to previous exposure to cosmic rays is an hazard when ultra-low background conditions are required. In this context, the generation of long-lived products by cosmic nucleons has been studied for many detector media and for other materials commonly used. Here, the main results obtained on the quantification of activation yields…
DarkSide (DS) at Gran Sasso underground laboratory is a direct dark matter search program based on TPCs with liquid argon from underground sources. The DS-50 TPC, with 50 kg of liquid argon is installed inside active neutron and muon detectors. DS-50 has been taking data since Nov 2013, collecting more than 10^7 events with atmospheric argon. This data represents an exposure to the largest background, beta decays of 39Ar, comparable to the full 3 y run of DS-50 with underground argon. When analysed with a threshold that would give a sensitivity in the full run of about 10^-45 cm2 at a WIMP mas…
The Argon Dark Matter (ArDM) experiment consists of a liquid argon (LAr) time projection chamber (TPC) sensitive to nuclear recoils resulting from scattering of hypothetical Weakly Interacting Massive Particles (WIMPs) on argon targets. With an active target of 850 kg, ArDM represents an important milestone in the quest for Dark Matter with LAr. We present the experimental apparatus currently installed underground at the Laboratorio Subterraneo de Canfranc (LSC), Spain. We show first data recorded during a single-phase commissioning run in 2015 (ArDM Run I), which overall confirm the good and …
The production of long-lived radioactive isotopes in materials due to the exposure to cosmic rays on Earth surface can be an hazard for experiments demanding ultra-low background conditions, typically performed deep underground. Production rates of cosmogenic isotopes in all the materials present in the experimental set-up, as well as the corresponding cosmic rays exposure history, must be both well known in order to assess the relevance of this effect in the achievable sensitivity of a given experiment. Although NaI(Tl) scintillators are being used in experiments aiming at the direct detectio…
In response to the growing need for low-radioactivity argon, community experts and interested parties came together for a 2-day workshop to discuss the worldwide low-radioactivity argon needs and the challenges associated with its production and characterization. Several topics were covered: experimental needs and requirements for low-radioactivity argon, the sources of low-radioactivity argon and its production, how long-lived argon radionuclides are created in nature, measuring argon radionuclides, and other applicable topics. The Low-Radioactivity Underground Argon (LRUA) workshop took plac…
The Argon Dark Matter (ArDM-1t) experiment is a ton-scale liquid argon (LAr) double-phase time projection chamber designed for direct Dark Matter searches. Such a device allows to explore the low energy frontier in LAr. After successful operation on surface at CERN, the detector has been deployed underground and is presently commissioned at the Canfranc Underground Laboratory (LSC). In this paper, we describe the status of the installation and present first results on data collected in gas phase.
Large liquid argon TPC detector programs such as LBNE and LAGUNA-LBNO will be able to make measurements of the proton lifetime which will outperform Cherenkov detectors in the proton decay channel $p \rightarrow K^{+}ν$. At the large depths which are proposed for such experiments, a non-negligible source of isolated charged kaons may be produced in the showers of cosmogenic muons. We present an estimate of the cosmogenic muon background to proton decay in the $p \rightarrow K^{+}ν$ channel. The simulation of muon transport to a depth of 4 km w.e, is performed in the MUSIC framework and the pro…
Cosmogenic activation in detector materials at shallow depths
South Dakota School of Mines and Technology（南达科他矿业理工学院）；University of South Dakota（南达科他大学）；Southern Methodist University（南方卫理公会大学）；Pacific Northwest National Laboratory（太平洋西北国家实验室）
The Deep Underground Neutrino Experiment (DUNE) will be a premier facility for exploring long-standing questions about the boundaries of the standard model. Acting in concert with the liquid argon time projection chambers underpinning the far detector design, the DUNE photon detection system will capture ultraviolet scintillation light in order to provide valuable timing information for event reconstruction. To maximize the active area while maintaining a small photocathode coverage, the experiment will utilize a design based on plastic light guides coated with a wavelength-shifting compound, …
The Argon Dark Matter experiment is a ton-scale double phase argon Time Projection Chamber designed for direct Dark Matter searches. It combines the detection of scintillation light together with the ionisation charge in order to discriminate the background (electron recoils) from the WIMP signals (nuclear recoils). After a successful operation on surface at CERN, the detector was recently installed in the underground Laboratorio Subterráneo de Canfranc, and the commissioning phase is ongoing. We describe the status of the installation and present first results from data collected underground …
GLACIER (Giant Liquid Argon Charge Imaging ExpeRiment) is a large underground observatory for proton decay search, neutrino astrophysics and CP-violation studies in the lepton sector. Possible underground sites are studied within the FP7 LAGUNA project (Europe) and along the JPARC neutrino beam in collaboration with KEK (Japan). The concept is scalable to very large masses.
DarkSide-50 is the first physics detector of the DarkSide dark matter search program. The detector features a dual-phase underground-argon Time Projection Chamber (TPC) of 50 kg active mass surrounded by an organic liquid-scintillator neutron veto (30 tons) and a water-Cherenkov muon detector (1000 tons). The TPC is currently fully shielded and operating underground at Gran Sasso National Laboratory. A first run of 1422 kg-day exposure with atmospheric argon represents the most sensitive dark matter search using a liquid argon target. The TPC is now filled with underground argon, greatly reduc…
The Deep Underground Neutrino Experiment (DUNE), a next-generation long-baseline neutrino oscillation experiment, is a powerful tool to perform low energy physics searches. DUNE will be uniquely sensitive to the electron-neutrino-flavour component of the burst of neutrinos expected from the next Galactic core-collapse supernova, and also capable of detecting solar neutrinos. DUNE will have four modules of 70-kton liquid argon mass in total, placed 1.5 km underground at the Sanford Underground Research Facility in the USA. These modules are being designed exploiting different liquid argon time …
One of the most powerful techniques for direct detection of dark matter via elastic scattering of galactic WIMPs is the use of liquid argon time projection chambers. Atmospheric argon (AAr) has a naturally occurring radioactive isotope, \ar{}, of cosmogenic origin. The use of argon extracted from underground wells, deprived of \ar{}, is key to the physics potential of these experiments. The DarkSide-20k (DS-20k) dark matter search experiment will operate with 50 tonnes of radio-pure underground argon (UAr), extracted from the Urania plant in Cortez (USA) and purified in the Aria distillation p…
ArgoNeuT (Argon Neutrino Test), a NSF/DOE project at Fermilab, is the first LArTPC to go in a low energy neutrino beam and just the second LArTPC to go in a neutrino beam ever. ArgoNeuT sits just upstream of the on-axis MINOS near detector in the NuMI beamline, about 1 km from the target station and 100 m underground. The detector features a 47X40X90 cm (169 L) active volume TPC with a fully contained recirculation and purification system. Among other physics, ArgoNeuT will measure the charged-current quasi-elastic (anti-) neutrino cross section on argon at an energy of ~3 GeV.
The Deep Underground Neutrino Experiment (DUNE) is a project to design, construct and operate a next-generation long-baseline neutrino detector with a liquid argon (LAr) target capable also of searching for proton decay and supernova neutrinos. It is a merger of previous efforts of the LBNE and LBNO collaborations, as well as other interested parties to pursue a broad programme with a staged 40 kt LAr detector at the Sanford Underground Research Facility (SURF) 1300 km from Fermilab. This programme includes studies of neutrino oscillations with a powerful neutrino beam from Fermilab, as well a…
The MicroBooNE experiment is a liquid argon TPC experiment designed for short-baseline neutrino physics, currently running at Fermilab. Due to its location near the surface, cosmic muons can be a source of backgrounds to many analyses and having a good understanding of the cosmic rays will be very valuable for the experiment. These proceedings describe the physics motivation, setup, and performance of a small external muon counter system, which will provide improved calibration for the liquid argon TPC and better understanding of the cosmogenic background.
DarkSide is a staged experimental project based on radiopure argon aiming at direct dark matter detection. The DarkSide-50 (DS-50) detector is currently operating underground at the Gran Sasso National Laboratory. DS-50 detector is a dual-phase, 50 kg, liquid argon time-projection-chamber readout by 38 cryogenic PMTs (Hamamatsu R11065), surrounded by an active liquid scintillator veto and contained in a water Cherenkov detector acting as a muon veto. DS-50 has been been operating continuously since 2013, first with atmospheric argon and subsequently filled in 2015 with argon from an undergroun…
We evaluated rates of transversing muons, muon-induced fast neutrons, and production of $^{40}$Cl and other cosmogenically produced nuclei that pose as potential sources of background to the physics program proposed for an argon-based long baseline neutrino experiment at the Sanford Underground Research Facility (SURF). The Geant4 simulations were carried out with muons and muon-induced neutrons for both 800 ft (0.712 km.w.e.) and 4850 ft levels (4.3 km.w.e.). We developed analytic models to independently calculate the $^{40}$Cl production using the measured muon fluxes at different levels of …
Muon-induced neutrons can lead to potentially irreducible backgrounds in rare event search experiments. We have investigated the implication of laboratory depth on the muon induced background in a future dark matter experiment capable of reaching the so-called neutrino floor. Our simulation study focuses on a xenon-based detector with 71 tonnes of active mass, surrounded by additional veto systems including an instrumented water shield. Two locations at the Boulby Underground Laboratory (UK) served as a case study: an experimental cavern in salt at a depth of 2850 m w.e. (similar to the locati…
The ANAIS experiment aims at the confirmation of the DAMA/LIBRA signal. A detailed analysis of two NaI(Tl) crystals of 12.5 kg each grown by Alpha Spectra will be shown: effective threshold at 1 keVee is at reach thanks to outstanding light collection and robust PMT noise filtering protocols and the measured background is well understood down to 3 keVee, having quantified K, U and Th content and cosmogenic activation in the crystals. A new detector was installed in Canfranc in March 2015 together with the two previous modules and preliminary characterization results will be presented. Finally,…
Large (up to $\sim 100$ kt) liquid argon time-projection chamber detectors are presently being considered for proton decay searches and neutrino astrophysics, as well as for far detectors for the next generation of long-baseline neutrino oscillation experiments that aim to determine neutrino mass hierarchy and search for CP violation in the leptonic sector. These detectors rely on the capabilities to assemble large volumes of LAr in ultrahigh-purity conditions, possibly in an underground environment, and to achieve relatively long drifts for the ionization charge. Several proposals have been d…
\Xe{136} is used as the target medium for many experiments searching for \bbnonu. Despite underground operation, cosmic muons that reach the laboratory can produce spallation neutrons causing activation of detector materials. A potential background that is difficult to veto using muon tagging comes in the form of \Xe{137} created by the capture of neutrons on \Xe{136}. This isotope decays via beta decay with a half-life of 3.8 minutes and a \Qb\ of $\sim$4.16 MeV. This work proposes and explores the concept of adding a small percentage of \He{3} to xenon as a means to capture thermal neutrons …
Liquid Argon Time Projection Chambers (LArTPCs) are ideal detectors for precision neutrino physics. These detectors, when located deep underground, can also be used for measurements of proton decay, and astrophysical neutrinos. The technology must be completely developed, up to very large mass scales, and fully mastered to construct and operate these detectors for this physics program. As part of an integrated plan of developing these detectors, accurate measurements in LArTPC of known particle species in the relevant energy ranges are now deemed as necessary. The LArIAT program aims to direct…
Liquid Argon Time Projection Chambers (LArTPCs) have been selected for the future long-baseline Deep Underground Neutrino Experiment (DUNE). To allow LArTPCs to operate in the high-multiplicity near detector environment of DUNE, a new charge readout technology is required. Traditional charge readout technologies introduce intrinsic ambiguities, combined with a slow detector response, these ambiguities have limited the performance of LArTPCs, until now. Here, we present a novel pixelated charge readout that enables the full 3D tracking capabilities of LArTPCs. We characterise the signal to nois…
Liquid Argon Time Projection Chambers are planned to comprise a central role in the future of the U.S. High Energy Physics neutrino program. In particular, this detector technology will form the basis for the 40 kton Deep Underground Neutrino Experiment (DUNE). In this paper we take as a starting point the dual phase far detector design proposed by the DUNE experiment and ask what changes are necessary to allow one of the four 10 kt modules to be sensitive to heavy Weakly Interacting Massive Particle (WIMP) dark matter. We show that with control over backgrounds and the use of low radioactivit…
The direct detection of dark matter particles requires ultra-low background conditions at energies below a few tens of keV. Radioactive isotopes are produced via cosmogenic activation in detectors and other materials and those isotopes constitute a background source which has to be under control. In particular, tritium is specially relevant due to its decay properties (very low endpoint energy and long half-life) when induced in the detector medium, and because it can be generated in any material as a spallation product. Quantification of cosmogenic production of tritium is not straightforward…
ICARUS T600 liquid argon time projection chamber is the first large mass electronic detector of a new generation able to combine the imaging capabilities of the old bubble chambers with the excellent calorimetric energy measurement. After the three months demonstration run on surface in Pavia during 2001, the T600 cryogenic plant was significantly revised, in terms of reliability and safety, in view of its long-term operation in an underground environment. The T600 detector was activated in Hall B of the INFN Gran Sasso Laboratory during Spring 2010, where it was operated without interruption …
We propose to measure the coherent elastic neutrino nucleus scattering (CE$ν$NS) using a dual-phase liquid argon time projection chamber (TPC) with 200kg fiducial mass. The detector is expected to be adjacent to the JUNO-TAO experiment and to be about 35m from a reactor core with 4.6GW thermal power at Taishan. The antineutrino flux is approximately 6$\times10^{12}$cm$^{-1}$s$^{-1}$ at this location, leading to more than 11,000 coherent scattering events per day in the fiducial mass. However, the nuclear recoil energies concentrate in the sub-keV region, corresponding to less than ten ionisati…
The China Dark Matter Experiment (CDEX) is a low background experiment at China Jinping Underground Laboratory (CJPL) designed to directly detect dark matter with a high-purity Germanium (HPGe) detector. In the second phase CDEX-10 with a 10 kg Germanium array detector system, the liquid argon (LAr) anti-compton active shielding and cooling system is proposed. For purpose of studying the properties of LAr detector, a prototype with an active volume of 7 liters of liquid argon was built and operated. The photoelectron yields, as a critically important parameter for the prototype detector, have …
ArDM is a new-generation WIMP detector which will measure simultaneously light and charge from scintillation and ionization of liquid argon. Our goal is to construct, characterize and operate a 1 ton liquid argon underground detector. The project relies on the possibility to extract the electrons produced by ionization from the liquid into the gas phase of the detector, to amplify and read out with Large Electron Multipliers detectors. Argon VUV scintillation light has to be converted with wavelength shifters such as TetraPhenyl Butadiene in order to be detected by photomultipliers with bialka…
The Deep Underground Neutrino Experiment (DUNE) is a 40-kton underground liquid argon time-projection-chamber (LAr TPC) detector, for long-baseline neutrino oscillation studies and for neutrino astrophysics and nucleon decay searches. Photon detector systems embedded within the LAr TPC add precise timing capabilities for non-beam events. The ProtoDUNE dual phase detector will consist of a 6x6x6 m3 liquid argon time-projection chamber placed at CERN and the light readout will be formed by 8-inch cryogenic photomultipliers from Hamamatsu. The characterization of the 36 photomultipliers, the base…
This paper will discuss a new method of signal read-out from photon detectors in ultra-large, underground liquid argon time projection chambers. In this design, the signal from the light collection system is coupled via capacitive plates to the TPC wire-planes. This signal is then read out using the same cabling and electronics as the charge information. This greatly benefits light collection: it eliminates the need for an independent readout, substantially reducing cost; It reduces the number of cables in the vapor region of the TPC that can produce impurities; And it cuts down on the number …
The last decade was remarkable for neutrino physics. In particular, the phenomenon of neutrino flavor oscillations has been firmly established by a series of independent measurements. All parameters of the neutrino mixing are now known and we have elements to plan a judicious exploration of new scenarios that are opened by these recent advances. With precise measurements, we can test the 3-neutrino paradigm, neutrino mass hierarchy and CP asymmetry in the lepton sector. The future long-baseline experiments are considered to be a fundamental tool to deepen our knowledge of electroweak interacti…
The SABRE (Sodium iodide with Active Background REjection) experiment aims to detect an annual rate modulation from dark matter interactions in ultra-high purity NaI(Tl) crystals in order to provide a model independent test of the signal observed by DAMA/LIBRA. It is made up of two separate detectors; SABRE South located at the Stawell Underground Physics Laboratory (SUPL), in regional Victoria, Australia, and SABRE North at the Laboratori Nazionali del Gran Sasso (LNGS). SABRE South is designed to disentangle seasonal or site-related effects from the dark matter-like modulated signal by using…
