Directional detection of nuclear recoils is broadly desirable in nuclear and particle physics. At low recoil energies, this capability may be used to confirm the cosmological origin of a dark matter signal, to penetrate the so-called neutrino floor, or to distinguish between different neutrino sources. Gas Time Projection Chambers (TPCs) can enable directional recoil detection if the readout granularity is sufficiently high, as is the case when micro-pattern gaseous detectors (MPGDs) are utilized. A key challenge in such detectors is identifying and rejecting background electron recoil events caused by gamma rays from radioactive contaminants in the detector materials and the environment. We define new observables that can distinguish electron and nuclear recoils, even at keV-scale energies, based on the simulated ionization's topology. We perform a simulation study that shows these observables outperform the traditionally used discriminant, dE/dx, by up to three orders of magnitude. Furthermore, these new observables work well even at ionization energies well below 10 keV and remain robust even in the regime where directionality fails.
We present measurements of light and charge signals in a dual-phase time projection chamber at electric fields varying from 10 V/cm up to 500 V/cm and at zero field using 511 keV gamma rays from a $^{22}$Na source. We determine the drift velocity, electron lifetime, diffusion constant, and light and charge yields at 511 keV as a function of the electric field. In addition, we fit the scintillation pulse shape to an effective exponential model, showing a decay time of 43.5 ns at low field that decreases to 25 ns at high fields.
Recoil-imaging gaseous time projection chambers (TPCs) with directional sensitivity are attractive for dark matter (DM) searches. Detectors capable of reconstructing 3D nuclear recoil directions would be uniquely sensitive to the predicted dipole angular distribution of DM recoils that would unambiguously establish the galactic origin of a claimed DM signal and provide powerful discrimination against background recoils from solar neutrinos. These advantages can only be exploited however, if electron recoil backgrounds from gamma rays can be sufficiently suppressed. We introduce a deep learning…
Bubble chambers using liquid xenon (and liquid argon) have been operated (resp. planned) by the Scintillating Bubble Chamber (SBC) collaboration for GeV-scale dark matter searches and CE$ν$NS from reactors. This will require a robust calibration program of the nucleation efficiency of low-energy nuclear recoils in these target media. Such a program has been carried out by the PICO collaboration, which aims to directly detect dark matter using $\mathrm{C_3 F_8}$ bubble chambers. Neutron calibration data from mono-energetic neutron beam and Am-Be source has been collected and analyzed, leading t…
Gaseous time projection chambers (TPCs) with high readout segmentation are capable of reconstructing detailed 3D ionization distributions of nuclear recoils resulting from elastic neutron scattering. Using a system of six compact TPCs with pixel ASIC readout, filled with a 70:30 mixture of He:CO$_2$ gas, we analyze the first directional measurements of beam-induced neutron backgrounds in the tunnel regions surrounding the Belle II detector at the SuperKEKB $e^+e^-$ collider. With the use of 3D recoil tracking, we show that these TPCs are capable of maintaining nearly $100\%$ nuclear recoil pur…
The viability of using a Bubble Chamber for rare event searches and in particular for the detection of dark matter particle candidates is considered. Techniques leading to the deactivation of inhomogeneous nucleation centers and subsequent enhanced stability in such a detector are described. Results from prototype trials indicate that sensitivity to low-energy nuclear recoils like those expected from Weakly Interacting Massive Particles can be obtained in conditions of near total insensitivity to minimum ionizing backgrounds. An understanding of the response of superheated heavy refrigerants t…
We develop and validate a new algorithm called \textit{primary track recovery} (\ptr) that effectively deconvolves known physics and detector effects from nuclear recoil tracks in gas time projection chambers (TPCs) with high-resolution readout. This gives access to the primary track charge, length, and vector direction (helping to resolve the "head-tail" ambiguity). Additionally, \ptr provides a measurement of the transverse and longitudinal diffusion widths, which can be used to determine the absolute position of tracks in the drift direction for detector fiducialization. Using simulated hel…
We describe the first demonstration of a sub-keV electron recoil energy threshold in a dual-phase liquid argon time projection chamber. This is an important step in an effort to develop a detector capable of identifying the ionization signal resulting from nuclear recoils with energies of order a few keV and below. We obtained this result by observing the peaks in the energy spectrum at 2.82 keV and 0.27 keV, following the K- and L-shell electron capture decay of Ar-37, respectively. The Ar-37 source preparation is described in detail, since it enables calibration that may also prove useful in…
The three-dimensional (3-D) reconstruction of nuclear recoils is of interest for directional detection of fast neutrons and for direction-sensitive searches for weakly interacting massive particles(WIMPs), which may constitute the Dark Matter of the universe. We demonstrate this capability with a miniature gas target Time Projection Chamber (TPC) where the drift charge is avalanche-multiplied with Gas Electron Multipliers (GEMs) and detected with the ATLAS FE-I3 Pixel Application Specific Integrated Circuit (ASIC). We report on performance characterization of the detector, including measuremen…
The design and performance of a 1.2 liter liquid xenon chamber equipped with 7 two-inch photomultiplier tubes, with the purpose of studying the scintillation response of xenon to gamma-rays and neutrons, is described. Measurements with gamma-rays indicate a high VUV light collection efficiency resulting in ~5.5 photoelectrons per 1 keV of deposited energy. The energy resolution (FWHM) is 18% and 22%, for 122 keV and 511 keV gamma-rays, respectively. An algorithm for the reconstruction of the scintillation coordinates in (x,y) plane was developed and tested. The position resolution is estimated…
Measurement of the three dimensional trajectory and specific ionization of recoil protons using a hydrogen gas time projection chamber provides directional information about incident fast neutrons. Here we demonstrate directional fast neutron detection using such a device. The wide field of view and excellent gamma rejection that are obtained suggest that this device is well suited to searches for special nuclear materials, among other applications.
The primary advantage of moderately superheated bubble chamber detectors is their simultaneous sensitivity to nuclear recoils from WIMP dark matter and insensitivity to electron recoil backgrounds. A comprehensive analysis of PICO gamma calibration data demonstrates for the first time that electron recoils in C$_3$F$_8$ scale in accordance with a new nucleation mechanism, rather than one driven by a hot-spike as previously supposed. Using this semi-empirical model, bubble chamber nucleation thresholds may be tuned to be sensitive to lower energy nuclear recoils while maintaining excellent elec…
A 30-g xenon bubble chamber, operated at Northwestern University in June and November 2016, has for the first time observed simultaneous bubble nucleation and scintillation by nuclear recoils in a superheated liquid. This chamber is instrumented with a CCD camera for near-IR bubble imaging, a solar-blind photomultiplier tube to detect 175-nm xenon scintillation light, and a piezoelectric acoustic transducer to detect the ultrasonic emission from a growing bubble. The time of nucleation determined from the acoustic signal is used to correlate specific scintillation pulses with bubble-nucleating…
Studies of micro time projection chambers using negative ion gas (NI$μ$TPC) are conducted especially for direction-sensitive dark matter searches. A NI$μ$TPC enables to measure the absolute position in the drift direction for self-triggering TPCs. This study provides a development of a NI$μ$TPC using a micro pixel chamber ($μ$-PIC) with dedicated readout electronics, and an evaluation of the capability of three-dimensional absolute position reconstruction of nuclear recoil using a neutron source. The absolute track position was reconstructed throughout the drift volume with an efficiency of 70…
The PICO experiment uses bubble chambers filled with superheated C$_3$F$_8$ for spin-dependent WIMP dark matter searches. One of the main sources of background in these detectors is alpha particles from decays of environmental $^{222}\mathrm{Rn}$, which nucleate bubbles that are visually indistinguishable from WIMP candidate events. Alpha-induced bubbles can be discriminated acoustically, because the signal from alpha events is consistently larger in magnitude than that from nuclear recoil/WIMP-like events. By studying the dynamics of bubbles nucleated by these two types of ionizing radiation …
We have directly measured the energy threshold and efficiency for bubble nucleation from iodine recoils in a CF3I bubble chamber in the energy range of interest for a dark matter search. These interactions cannot be probed by standard neutron calibration methods, so we develop a new technique by observing the elastic scattering of 12 GeV/c negative pions. The pions are tracked with a silicon pixel telescope and the reconstructed scattering angle provides a measure of the nuclear recoil kinetic energy. The bubble chamber was operated with a nominal threshold of (13.6+-0.6) keV. Interpretation o…
We present a comprehensive analysis of electronic recoil vs. nuclear recoil discrimination in liquid/gas xenon time projection chambers, using calibration data from the 2013 and 2014-16 runs of the Large Underground Xenon (LUX) experiment. We observe strong charge-to-light discrimination enhancement with increased event energy. For events with S1 = 120 detected photons, i.e. equivalent to a nuclear recoil energy of $\sim$100 keV, we observe an electronic recoil background acceptance of $<10^{-5}$ at a nuclear recoil signal acceptance of 50%. We also observe modest electric field dependence of …
Ton-scale direct dark matter search experiments should be sensitive to neutrino-induced recoil events from either $^8$B solar neutrinos or the brief but intense flux from a core collapse supernova in the Milky Way. These low-threshold detectors are sensitive to the very low recoil energies, of order 10 keV, deposited via coherent elastic scatters between supernova neutrinos and target nuclei. Large superheated fluid detectors like PICO-500, a bubble chamber to be initially filled with an active target of 1 t of C$_3$F$_8$, should see multiple-bubble events from CE$ν$NS if the detector is live …
Understanding the ability to measure and discriminate particle events at the lowest possible energy is an essential requirement in developing new experiments to search for weakly interacting massive particle (WIMP) dark matter. In this paper we detail an assessment of the potential sensitivity below 10 keV in the 1 m^3 DRIFT-II directionally sensitive, low pressure, negative ion time projection chamber (NITPC), based on event-by-event track reconstruction and calorimetry in the multiwire proportional chamber (MWPC) readout. By application of a digital smoothing polynomial it is shown that the …
New data are reported from the operation of a 2-liter C$_3$F$_8$ bubble chamber in the 2100 meter deep SNOLAB underground laboratory, with a total exposure of 211.5 kg-days at four different recoil energy thresholds ranging from 3.2 keV to 8.1 keV. These data show that C3F8 provides excellent electron recoil and alpha rejection capabilities at very low thresholds, including the first observation of a dependence of acoustic signal on alpha energy. Twelve single nuclear recoil event candidates were observed during the run. The candidate events exhibit timing characteristics that are not consiste…
Recent computational results suggest that directional dark matter detectors have potential to probe for WIMP dark matter particles below the neutrino floor. The DRIFT-IId detector used in this work is a leading directional WIMP search time projection chamber detector. We report the first measurements of the detection of the directional nuclear recoils in a fully fiducialised low-pressure time projection chamber. In this new operational mode, the distance between each event vertex and the readout plane is determined by the measurement of minority carriers produced by adding a small amount of ox…
We present a measurement of scintillation efficiency for a few tens of keV nuclear recoils (NR) with a liquid argon time projection chamber under electric fields ranging from $0$ to $3\ {\rm kV/cm}$. The calibration data are taken with $^{252}{\rm Cf}$ radioactive source. Observed scintillation and electroluminescence spectra are simultaneously fit with spectra derived from Geant4-based Monte Carlo simulation and an NR model. The scintillation efficiency extracted from the fit is reported as a function of recoil energy and electric field. This result can be used for designing the detector and …
MIMAC (MIcro-TPC MAtrix of Chambers) is a directional WIMP Dark Matter detector project. Direct dark matter experiments need a high level of electron/recoil discrimination to search for nuclear recoils produced by WIMP-nucleus elastic scattering. In this paper, we proposed an original method for electron event rejection based on a multivariate analysis applied to experimental data acquired using monochromatic neutron fields. This analysis shows that a $10^5$ rejection power is reachable for electron/recoil discrimination. Moreover, the efficiency was estimated by a Monte-Carlo simulation showi…
The AMANDE facility at IRSN-Cadarache produces mono-energetic neutron fields from 2 keV to 20 MeV with metrological quality. To be considered as a standard facility, characteristics of neutron field i.e fluence distribution must be well known by a device using absolute measurements. The development of new detector systems allowing a direct measurement of neutron energy and fluence has started in 2006. Using the proton recoil telescope principle with the goal of increase the efficiency, two systems with full localization are studied. A proton recoil telescope using CMOS sensor (CMOS-RPT) is stu…
The HARP system of resistive plate chambers (RPCs) was designed to perform particle identification by the measurement of the difference in the time-of-flight of different particles. In previous papers an apparent discrepancy was shown between the response of the RPCs to minimum ionizing pions and heavily ionizing protons. Using the kinematics of elastic scattering off a hydrogen target a controlled beam of low momentum recoil protons was directed onto the chambers. With this method the trajectory and momentum, and hence the time-of-flight of the protons can be precisely predicted without need …
We report on the design, production, and performance of compact 40-cm$^3$ Time Projection Chambers (TPCs) that detect fast neutrons by measuring the three-dimensional (3D) ionization distribution of nuclear recoils in $^4$He:CO$_2$ gas at atmospheric pressure. We use these detectors to characterize the fast-neutron flux inside the Belle II detector at the SuperKEKB electron-positron collider in Tsukuba, Japan, where the primary design constraint is a small form factor. We find that the TPCs meet or exceed all design specifications, and are capable of measuring the 3D surface shape and charge d…
Measuring the scintillation and ionization yields of liquid xenon in response to ultra-low energy nuclear recoil events is necessary to increase the sensitivity of liquid xenon experiments to light dark matter. Neutron capture on xenon can be used to produce nuclear recoil events with energies below $0.3$ keV$_\text{NR}$ via the asymmetric emission of $γ$ rays during nuclear de-excitation. The feasibility of an ultra-low energy nuclear recoil measurement using neutron capture was investigated for the Michigan Xenon (MiX) detector, a small dual-phase xenon time projection chamber that is optimi…
The MIMAC experiment is a $μ$-TPC matrix project for directional dark matter search. Directional detection is a strategy based on the measurement of the WIMP flux anisotropy due to the solar system motion with respect to the dark matter halo. The main purpose of MIMAC project is the measurement of the energy and the direction of nuclear recoils in 3D produced by elastic scattering of WIMPs. Since June 2012 a bi-chamber prototype is operating at the Modane underground laboratory. In this paper, we report the first ionization energy and 3D track observations of nuclear recoils produced by the ra…
We present work on the detection of neutral particles via nuclear recoils in gas-filled Time Projection Chambers (TPCs). We employ Gas Electron Multipliers (GEMs) to amplify the signal and silicon pixel electronics to detect the avalanche charge. These technologies allow ionization in the target gas to be detected with low noise, improved position and time resolution, and high efficiency. We review experimental results obtained in previous years, and report on ongoing simulation studies and construction of the first prototype at the University of Hawaii. We also present prospects of using such…
The search for dark matter is one of today's most exciting fields. As bigger detectors are being built to increase their sensitivity, background reduction is an ever more challenging issue. To this end, a new type of dark matter detector is proposed, a xenon bubble chamber, which would combine the strengths of liquid xenon TPCs, namely event by event energy resolution, with those of a bubble chamber, namely insensitivity to electronic recoils. In addition, it would be the first time ever that a dark matter detector is active on all three detection channels, ionization and scintillation charact…
3D-Deuteron Track Recoils Produced by Neutron Capture in Hydrogen Measured by MIMAC-35 cm
LPSC, Université Grenoble Alpes, CNRS/IN2P3（格勒诺布尔阿尔卑斯大学粒子物理与核物理实验室）；Centre de Physique des Particules de Marseille, IN2P3/CNRS and Université Aix-Marseille（马赛粒子物理中心）
We present new measurements of the scintillation and ionization yields in liquid xenon for low energy electronic (about 3--7 keV$_{ee}$) and nuclear recoils (about 8--20 keV$_{nr}$) at different drift fields from 236 V/cm to 3.93 kV/cm, using a three-dimensional sensitive liquid xenon time projection chamber with high energy and position resolutions. Our measurement of signal responses to nuclear recoils agrees with predictions from the NEST model. However, our measured ionization (scintillation) yields for electronic recoils are consistently higher (lower) than those from the NEST model by ab…
We have exposed a dual-phase Liquid Argon Time Projection Chamber (LAr-TPC) to a low energy pulsed narrowband neutron beam, produced at the Notre Dame Institute for Structure and Nuclear Astrophysics to study the scintillation light yield of recoiling nuclei in a LAr-TPC. A liquid scintillation counter was arranged to detect and identify neutrons scattered in the LAr-TPC target and to select the energy of the recoiling nuclei. We report the observation of a significant dependence on drift field of liquid argon scintillation from nuclear recoils of 11 keV. This observation is important because,…
Liquid xenon-based direct detection dark matter experiments have recently expanded their searches to include high-energy nuclear recoil events as motivated by effective field theory dark matter and inelastic dark matter interaction models, but few xenon recoil calibrations above 100 keV are currently available. In this work, we measured the scintillation and ionization yields of xenon recoils up to 426 keV. The experiment uses 14.1 MeV neutrons to scatter off xenon in a compact liquid xenon time projection chamber and produce quasi-monoenergetic xenon recoils between 39 keV and 426 keV. We rep…
Directional detection of dark matter can provide unambiguous observation of dark matter interactions even in the presence of background. This article presents an experimental method to measure the direction tag ("head-tail") of the dark matter wind by detecting the scintillation light created by the elastic nuclear recoils in the scattering of dark matter particles with the detector material. The technique is demonstrated by tagging the direction of the nuclear recoils created in the scattering of low-energy neutrons with CF4 in a low-pressure time-projection chamber that is developed by the D…
Absolute measurements of neutron flux are an essential prerequisite of neutron-induced cross section measurements, neutron beam lines characterization and dosimetric investigations. A new gaseous detector has been developed for measurements of 0.2 to 2 MeV neutron flux based on proton-recoil process. The detector, consisting of two segmented ionization chambers read by Micromegas technology, has beed conceived to provide quasi-absolute neutron flux measurements with an accuracy of \simeq3%. The gas pressure flexibility makes the telescope non sensitive to γ and electrons background, and theref…
New results are reported from the operation of the PICO-60 dark matter detector, a bubble chamber filled with 52 kg of C$_3$F$_8$ located in the SNOLAB underground laboratory. As in previous PICO bubble chambers, PICO-60 C$_3$F$_8$ exhibits excellent electron recoil and alpha decay rejection, and the observed multiple-scattering neutron rate indicates a single-scatter neutron background of less than 1 event per month. A blind analysis of an efficiency-corrected 1167-kg-day exposure at a 3.3-keV thermodynamic threshold reveals no single-scattering nuclear recoil candidates, consistent with the …
Directional detection of non-baryonic Dark Matter is a promising search strategy for discriminating WIMP events from neutrons, the ultimate background for dark matter direct detection. This strategy requires both a precise measurement of the energy down to a few keV and 3D reconstruction of tracks down to a few mm. The MIMAC (MIcro-tpc MAtrix of Chambers) collaboration has developed in the last years an original prototype detector based on the direct coupling of large pixelized micromegas with a special developed fast self-triggered electronics showing the feasibility of a new generation of di…
The aim of the CYGNO project is the construction and operation of a 1~m$^3$ gas TPC for directional dark matter searches and coherent neutrino scattering measurements, as a prototype toward the 100-1000~m$^3$ (0.15-1.5 tons) CYGNUS network of underground experiments. In such a TPC, electrons produced by dark-matter- or neutrino-induced nuclear recoils will drift toward and will be multiplied by a three-layer GEM structure, and the light produced in the avalanche processes will be readout by a sCMOS camera, providing a 2D image of the event with a resolution of a few hundred micrometers. Photom…
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 …
A new Radial Time Projection Chamber (RTPC) was developed at the Jefferson Laboratory to track low-energy nuclear recoils for the purpose of measuring exclusive nuclear reactions, such as coherent Deeply Virtual Compton Scattering and coherent meson production off $^4$He. In such processes, the $^4$He nucleus remains intact in the final state, however the CEBAF Large Acceptance Spectrometer (CLAS) cannot track the low energy $α$ particles. In 2009, we carried out measurements using the CLAS spectrometer supplemented by the RTPC positioned directly around a gaseous $^4$He target, allowing a det…
Searches for dark matter-induced recoils have made impressive advances in the last few years. Yet the field is confronted by several outstanding problems. First, the inevitable background of solar neutrinos will soon inhibit the conclusive identification of many dark matter models. Second, and more fundamentally, current experiments have no practical way of confirming a detected signal's galactic origin. The concept of directional detection addresses both of these issues while offering opportunities to study novel dark matter and neutrino-related physics. The concept remains experimentally cha…
Diamonds are very promising candidates for the neutron diagnostics in harsh environments such as fusion reactor. In the first place this is because of their radiation hardness, exceeding that of Silicon by an order of magnitude. Also, in comparison to the standard on-line neutron diagnostics (fission chambers, silicon based detectors, scintillators), diamonds are less sensitive to $γ$ rays, which represent a huge background in fusion devices. Finally, their low leakage current at high temperature suppresses the detector intrinsic noise. In this talk a CVD diamond based detector has been propos…
The Time Projection Chamber (TPC) is an ideal candidate to finely study the charged particle ionization in a gaseous medium. Large volumes TPCs can be read out with a suitable number of channels offering a complete 3D reconstruction of an ultra-relativistic charged particle track, that is the sequence of its energy releases in the TPC gas volume. Moreover, He-based TPCs are very promising to study keV energy particles as nuclear recoils, opening the possibility for directional searches of Dark Matter (DM) and the study of Solar Neutrinos (SN). In this paper, we report the analysis of the data …
We present results from the first deployment of novel, high definition, compact gas Time Projection Chambers (TPCs) with pixel chip readout as part of the BEAST II beam background measurement project at SuperKEKB. The TPCs provide detailed 3D imaging of ionization from neutron-induced nuclear recoils in a helium and carbon dioxide target gas mixture at standard temperature and pressure. We find excellent electron background rejection, leading to background-free nuclear recoil measurements above 50 keVee, despite the extreme high-background environment. We measure an angular resolution better t…
We propose a new technique for the calibration of nuclear recoils in large noble element dual-phase time projection chambers used to search for WIMP dark matter in the local galactic halo. This technique provides an $\textit{in situ}$ measurement of the low-energy nuclear recoil response of the target media using the measured scattering angle between multiple neutron interactions within the detector volume. The low-energy reach and reduced systematics of this calibration have particular significance for the low-mass WIMP sensitivity of several leading dark matter experiments. Multiple strategi…
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 …
We report a systematic determination of the responses of PandaX-II, a dual phase xenon time projection chamber detector, to low energy recoils. The electron recoil (ER) and nuclear recoil (NR) responses are calibrated, respectively, with injected tritiated methane or $^{220}$Rn source, and with $^{241}$Am-Be neutron source, within an energy range from $1-25$ keV (ER) and $4-80$ keV (NR), under the two drift fields of 400 and 317 V/cm. An empirical model is used to fit the light yield and charge yield for both types of recoils. The best fit models can well describe the calibration data. The sys…
Directional detection is a promising direct Dark Matter (DM) search strategy. The angular distribution of the nuclear recoil tracks from WIMP events should present an anisotropy in galactic coordinates. This strategy requires both a measurement of the recoil energy with a threshold of about 5 keV and 3D recoil tracks down to few millimeters. The MIMAC project, based on a \textmu-TPC matrix, with $CF_4$ and $CHF_3$, is being developed. In June 2012, a bi-chamber prototype was installed at the LSM (Laboratoire Souterrain de Modane). A preliminary analysis of the first four months data taking all…
A gaseous time-projection chamber (TPC) with a reconstructable $z$ coordinate for nuclear recoil tracks has been developed for dark-matter searches and $α$ particle imagings in a low radioactivity background. A TPC with a sheet-resistor field cage shows a potential to detect charge and photons produced by tracks if the sheet resistor has optical transmittance for visible light, and determine a drift length from a time difference between these signals. In this study, an optical transmittance of sheet resistors was measured to be $24.5\pm0.1_{\rm stat}\pm0.6_{\rm syst}\%$ for the $\rm {CF}_4$ ga…
This paper describes a novel directional neutron detector prototype. The low pressure time projection chamber uses a mix of helium and CF4 gases. The detector reconstructs the energy and angular distribution of fast neutron recoils. This paper reports results of energy calibration using an alpha source and angular reconstruction studies using a collimated neutron source. The best performance is obtained with a 12.5% CF4 gas mixture. At low energies the target for fast neutrons transitions is primarily helium, while at higher energies, the fluorine contributes as a target. The reconstruction ef…
A liquid argon time projection chamber, constructed for the Argon Response to Ionization and Scintillation (ARIS) experiment, has been exposed to the highly collimated and quasi-monoenergetic LICORNE neutron beam at the Institute de Physique Nuclaire Orsay in order to study the scintillation response to nuclear and electronic recoils. An array of liquid scintillator detectors, arranged around the apparatus, tag scattered neutrons and select nuclear recoil energies in the [7, 120] keV energy range. The relative scintillation efficiency of nuclear recoils was measured to high precision at null f…
The DMTPC directional dark matter detection experiment is a low-pressure CF4 gas time projection chamber, instrumented with charge and scintillation photon readout. This detector design strategy emphasizes reconstruction of WIMP-induced nuclear recoil tracks, in order to determine the direction of incident dark matter particles. Directional detection has the potential to make the definitive observation of dark matter using the unique angular signature of the dark matter wind, which is distinct from all known backgrounds. This talk will briefly review the experimental technique and current stat…
The MuCap experiment at the Paul Scherrer Institute performed a high-precision measurement of the rate of the basic electroweak process of nuclear muon capture by the proton, $μ^- + p \rightarrow n + ν_μ$. The experimental approach was based on the use of a time projection chamber (TPC) that operated in pure hydrogen gas at a pressure of 10 bar and functioned as an active muon stopping target. The TPC detected the tracks of individual muon arrivals in three dimensions, while the trajectories of outgoing decay (Michel) electrons were measured by two surrounding wire chambers and a plastic scint…
