arXiv subjects

A. Manzur

Publications and source records attributed to A. Manzur.

14 recordsLinked to original sources

arXiv2013

A search for light dark matter in XENON10 data

We report results of a search for light (<10 GeV) particle dark matter with the XENON10 detector. The event trigger was sensitive to a single electron, with the analysis threshold of 5 electrons corresponding to 1.4 keV nuclear recoil energy. Considering spin-independent dark matter-nucleon scattering, we exclude cross sections σ_n>3.5x10^{-42} cm^2, for a dark matter particle mass m_χ=8 GeV. We find that our data strongly constrain recent elastic dark matter interpretations of excess low-energy events observed by CoGeNT and CRESST-II, as well as the DAMA annual modulation signal.

astro-ph.CO↗

arXiv2012

The distributed Slow Control System of the XENON100 Experiment

The XENON100 experiment, in operation at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy, was designed to search for evidence of dark matter interactions inside a volume of liquid xenon using a dual-phase time projection chamber. This paper describes the Slow Control System (SCS) of the experiment with emphasis on the distributed architecture as well as on its modular and expandable nature. The system software was designed according to the rules of Object-Oriented Programming and coded in Java, thus promoting code reusability and maximum flexibility during commissioning of the experiment. The SCS has been continuously monitoring the XENON100 detector since mid 2008, remotely recording hundreds of parameters on a few dozen instruments in real time, and setting emergency alarms for the most important variables.

astro-ph.IM↗

arXiv2010

Lowering the low-energy threshold of xenon detectors

We show that the energy threshold for nuclear recoils in the XENON10 dark matter search data can be lowered to ~1 keV, by using only the ionization signal. In other words, we make no requirement that a valid event contain a primary scintillation signal. We therefore relinquish incident particle type discrimination, which is based on the ratio of ionization to scintillation in liquid xenon. This method compromises the detector's ability to precisely determine the z coordinate of a particle interaction. However, we show for the first time that it is possible to discriminate bulk events from surface events based solely on the ionization signal.

astro-ph.IM↗

arXiv2010

Constraints on inelastic dark matter from XENON10

It has been suggested that dark matter particles which scatter inelastically from detector target nuclei could explain the apparent incompatibility of the DAMA modulation signal (interpreted as evidence for particle dark matter) with the null results from CDMS-II and XENON10. Among the predictions of inelastically interacting dark matter are a suppression of low-energy events, and a population of nuclear recoil events at higher nuclear recoil equivalent energies. This is in stark contrast to the well-known expectation of a falling exponential spectrum for the case of elastic interactions. We present a new analysis of XENON10 dark matter search data extending to E$_{nr}=75$ keV nuclear recoil equivalent energy. Our results exclude a significant region of previously allowed parameter space in the model of inelastically interacting dark matter. In particular, it is found that dark matter particle masses $m_χ\gtrsim150$ GeV are disfavored.

astro-ph.CO↗

arXiv2010

A 83Krm Source for Use in Low-background Liquid Xenon Time Projection Chambers

We report the testing of a charcoal-based Kr-83m source for use in calibrating a low background two-phase liquid xenon detector. Kr-83m atoms produced through the decay of Rb-83 are introduced into a xenon detector by flowing xenon gas past the Rb-83 source. 9.4 keV and 32.1 keV transitions from decaying 83Krm nuclei are detected through liquid xenon scintillation and ionization. The characteristics of the Kr-83m source are analyzed and shown to be appropriate for a low background liquid xenon detector. Introduction of Kr-83m allows for quick, periodic calibration of low background noble liquid detectors at low energy.

physics.ins-det↗

arXiv2010

Scintillation efficiency and ionization yield of liquid xenon for mono-energetic nuclear recoils down to 4 keV

Liquid Xenon (LXe) is an excellent material for experiments designed to detect dark matter in the form of Weakly Interacting Massive Particles (WIMPs). A low energy detection threshold is essential for a sensitive WIMP search. The understanding of the relative scintillation efficiency (Leff) and ionization yield of low energy nuclear recoils in LXe is limited for energies below 10 keV. In this paper, we present new measurements that extend the energy down to 4 keV, finding that Leff decreases with decreasing energy. We also measure the quenching of scintillation efficiency due to the electric field in LXe, finding no significant field dependence.

physics.ins-det↗

arXiv2010

Design and Performance of the XENON10 Dark Matter Experiment

XENON10 is the first two-phase xenon time projection chamber (TPC) developed within the XENON dark matter search program. The TPC, with an active liquid xenon (LXe) mass of about 14 kg, was installed at the Gran Sasso underground laboratory (LNGS) in Italy, and operated for more than one year, with excellent stability and performance. Results from a dark matter search with XENON10 have been published elsewhere. In this paper, we summarize the design and performance of the detector and its subsystems, based on calibration data using sources of gamma-rays and neutrons as well as background and Monte Carlo simulations data. The results on the detector's energy threshold, energy and position resolution, and overall efficiency show a performance that exceeds design specifications, in view of the very low energy threshold achieved (<10 keVr) and the excellent energy resolution achieved by combining the ionization and scintillation signals, detected simultaneously.

astro-ph.IM↗

arXiv2009

Calibration of a Liquid Xenon Detector with Kr-83m

We report the preparation of a Kr-83m source and its subsequent use in calibrating a liquid xenon detector. Kr-83m atoms were produced through the decay of Rb-83 atoms trapped in zeolite molecular sieve and were then introduced into liquid xenon. Decaying Kr-83m nuclei were detected through liquid xenon scintillation. Conversion electrons with energies of 9.4 keV and 32.1 keV from the decay of Kr-83m were both observed. This calibration source will allow the characterization of the scintillation and ionization response of noble liquid detectors at low energies, highly valuable for the search for WIMP dark matter. Kr-83m may also be useful for measuring fluid flow dynamics, both to understand purification in noble liquid-based particle detectors, as well as for studies of classical and quantum turbulence in superfluid helium.

physics.ins-det↗

arXiv2008

The scintillation and ionization yield of liquid xenon for nuclear recoils

XENON10 is an experiment designed to directly detect particle dark matter. It is a dual phase (liquid/gas) xenon time-projection chamber with 3D position imaging. Particle interactions generate a primary scintillation signal (S1) and ionization signal (S2), which are both functions of the deposited recoil energy and the incident particle type. We present a new precision measurement of the relative scintillation yield \leff and the absolute ionization yield Q_y, for nuclear recoils in xenon. A dark matter particle is expected to deposit energy by scattering from a xenon nucleus. Knowledge of \leff is therefore crucial for establishing the energy threshold of the experiment; this in turn determines the sensitivity to particle dark matter. Our \leff measurement is in agreement with recent theoretical predictions above 15 keV nuclear recoil energy, and the energy threshold of the measurement is 4 keV. A knowledge of the ionization yield \Qy is necessary to establish the trigger threshold of the experiment. The ionization yield \Qy is measured in two ways, both in agreement with previous measurements and with a factor of 10 lower energy threshold.

astro-ph↗

arXiv2008

Limits on spin-dependent WIMP-nucleon cross-sections from the XENON10 experiment

XENON10 is an experiment to directly detect weakly interacting massive particle (WIMPs), which may comprise the bulk of the non-baryonic dark matter in our Universe. We report new results for spin-dependent WIMP-nucleon interactions with 129-Xe and 131-Xe from 58.6 live-days of operation at the Laboratori Nazionali del Gran Sasso (LNGS). Based on the non-observation of a WIMP signal in 5.4 kg of fiducial liquid xenon mass, we exclude previously unexplored regions in the theoretically allowed parameter space for neutralinos. We also exclude a heavy Majorana neutrino with a mass in the range of 10 GeV -2 TeV as a dark matter candidate under standard assumptions for its density and distribution in the galactic halo.

astro-ph↗

arXiv2007

First Results from the XENON10 Dark Matter Experiment at the Gran Sasso National Laboratory

The XENON10 experiment at the Gran Sasso National Laboratory uses a 15 kg xenon dual phase time projection chamber (XeTPC) to search for dark matter weakly interacting massive particles (WIMPs). The detector measures simultaneously the scintillation and the ionization produced by radiation in pure liquid xenon, to discriminate signal from background down to 4.5 keV nuclear recoil energy. A blind analysis of 58.6 live days of data, acquired between October 6, 2006 and February 14, 2007, and using a fiducial mass of 5.4 kg, excludes previously unexplored parameter space, setting a new 90% C.L. upper limit for the WIMP-nucleon spin-independent cross-section of 8.8 x 10^{-44} cm^2 for a WIMP mass of 100 GeV/c^2, and 4.5 x 10^{-44} cm^2 for a WIMP mass of 30 GeV/c^2. This result further constrains predictions of supersymmetric models.

astro-ph↗

arXiv2007

Preparation of Neutron-activated Xenon for Liquid Xenon Detector Calibration

We report the preparation of neutron-activated xenon for the calibration of liquid xenon (LXe) detectors. Gamma rays from the decay of xenon metastable states, produced by fast neutron activation, were detected and their activities measured in a LXe scintillation detector. Following a five-day activation of natural xenon gas with a Cf-252 (4 x 10^5 n/s) source, the activities of two gamma ray lines at 164 keV and 236 keV, from Xe-131m and Xe-129m metastable states, were measured at about 95 and 130 Bq/kg, respectively. We also observed three additional lines at 35 keV, 100 keV and 275 keV, which decay away within a few days. No long-lifetime activity was observed after the neutron activation.

physics.ins-det↗

arXiv2006

3D Position Sensitive XeTPC for Dark Matter Search

The technique to realize 3D position sensitivity in a two-phase xenon time projection chamber (XeTPC) for dark matter search is described. Results from a prototype detector (XENON3) are presented.

astro-ph↗

arXiv2005

Scintillation Response of Liquid Xenon to Low Energy Nuclear Recoils

Liquid Xenon (LXe) is expected to be an excellent target and detector medium to search for dark matter in the form of Weakly Interacting Massive Particles (WIMPs). Knowledge of LXe ionization and scintillation response to low energy nuclear recoils expected from the scattering of WIMPs by Xe nuclei is important for determining the sensitivity of LXe direct detection experiments. Here we report on new measurements of the scintillation yield of Xe recoils with kinetic energy as low as 10 keV. The dependence of the scintillation yield on applied electric field was also measured in the range of 0 to 4 kV/cm. Results are in good agreement with recent theoretical predictions that take into account the effect of biexcitonic collisions in addition to the nuclear quenching effect.

astro-ph↗