17320714
Background light in potential sites for the ANTARES undersea neutrino telescope
Abstract The ANTARES collaboration has performed a series of in-situ measurements to study the background light for a planned undersea neutrino telescope. Such background can be caused by 40 K decays or by biological activity. We report on measurements at two sites in the Mediterranean Sea at depths of 2400 m and 2700 m, respectively. Three photomultiplier tubes were used to measure single counting rates and coincidence rates for pairs of tubes at various distances. The background rate is seen to consist of three components: a constant rate due to 40 K decays, a continuum rate that varies on a time scale of several hours simultaneously over distances up to at least 40 m, and random bursts a few seconds long that are only correlated in time over distances of the order of a meter. A trigger requiring coincidences between nearby photomultiplier tubes should reduce the trigger rate for a neutrino telescope to a manageable level with only a small loss in efficiency.
121667127
The potential of liquid xenon for WIMP search: the ZEPLIN diagnostic array
Abstract A Liquid Xenon based WIMP detector diagnostic array is currently developed by the UKDMC with the help of international collaborators. After a brief reminder on the detection principle in Liquid Xenon, the individual detectors will be described. ZEPLIN I, a detector with a 4 kg fiducial mass with a background discrimination based on Pulse Shape Analysis, is already underground and starting operation. Two setups with improved background discrimination tools (as the ionisation is also recorded) are designed and scheduled to move underground in the second half of 2001. Both of them, ZEPLIN II and ZEPLIN III, are predicted to be sensitive to rate of 0.1–0.01 events/kg/day within 2 years of data taking. Furthermore, new ideas for lower background readout devices are studied, in order to avoid the use of PhotoMultiplier Tubes (PMTs).
12347950
The ZEPLIN-III dark matter detector: Performance study using an end-to-end simulation tool
We present results from a GEANT4-based Monte Carlo tool for end-to-end simulations of the ZEPLIN-III dark matter experiment. ZEPLIN-III is a two-phase detector which measures both the scintillation light and the ionisation charge generated in liquid xenon by interacting particles and radiation. The software models the instrument response to radioactive backgrounds and calibration sources, including the generation, ray-tracing and detection of the primary and secondary scintillations in liquid and gaseous xenon, and subsequent processing by data acquisition electronics. A flexible user interface allows easy modification of detector parameters at run time. Realistic datasets can be produced to help with data analysis, an example of which is the position reconstruction algorithm developed from simulated data. We present a range of simulation results confirming the original design sensitivity of a few times 10−8 pb to the WIMP-nucleon cross-section.
120314532
Progress report from the UK Dark Matter search at Boulby Mine
Abstract The UK Dark Matter Collaboration is currently running a series of scintillation devices at the Boulby mine in North Yorkshire to search for the neutralino, the hypothetical WIMP solution to the dark matter problem. Results of the current NaI(T1) detector array will be discussed, illustrating a population of events of unknown origin. Diagnostic tests performed to investigate the origin of these anomalous events will be outlined, including alpha, beta and neutron calibrations.
115887438
Particle polarization in inclusive reactions
119286983
Muon-induced background in the EDELWEISS dark matter search
Abstract A dedicated analysis of the muon-induced background in the EDELWEISS dark matter search has been performed on a data set acquired in 2009 and 2010. The total muon flux underground in the Laboratoire Souterrain de Modane (LSM) was measured to be Φ μ = ( 5.4 ± 0.2 - 0.9 + 0.5 )  muons/m 2 /d. The modular design of the μ -veto system allows the reconstruction of the muon trajectory and hence the determination of the angular dependent muon flux in LSM. The results are in good agreement with both MC simulations and earlier measurements. Synchronization of the μ -veto system with the phonon and ionization signals of the Ge detector array allowed identification of muon-induced events. Rates for all muon-induced events Γ μ = ( 0.172 ± 0.012 ) evts / ( kg d ) and of WIMP-like events Γ μ – n = 0.008 - 0.004 + 0.005 evts / ( kg d ) were extracted. After vetoing, the remaining rate of accepted muon-induced neutrons in the EDELWEISS-II dark matter search was determined to be Γ irred μ – n 6 · 10 - 4 evts / ( kg d ) at 90% C.L. Based on these results, the muon-induced background expectation for an anticipated exposure of 3000 kg d for EDELWEISS-III is N 3000 kg d μ – n 0.6 events.
123747264
Heavy states of hadron string as weak interacting massive particles for Dark Matter
Massive states (of order 10 Gev and more) of hadron string (with scale 1 Gev) can have very small coupling constants with usual baryons of the Universe. Corresponding mean times for them are found to be order and even more than the age of the Universe. They are proposed as possible candidates for weak interacting massive particles (WIMP) of Dark Matter.
116402726
Superfermionic superconformal string model
115452072
Production of high-energy muons in extensive air showers from primary el rays
The primary mechanism for the production of high-energy muons (E/sub / > 5 TeV) in extensive air showers from primary el rays is the production of muon pairs by shower photons in the field of a nucleus.
119252315
HADRON AMPLITUDES IN COMPOSITE SUPERCONFORMAL STRING MODEL
Dynamics of π, K-mesons interactions is formulated in terms of composite superconformal string model. Supersymmetry is defined on two-dimensional world surface only. Dimensionality of target space equals to four. The model treats usual hadron scale which is of order 1 GeV-2, as string scale α′. Intercept of leading meson trajectory equals to ½. Tree amplitudes are free from ghosts in physical state spectrum in accordance with usual classical superstring amplitudes. Interaction of π-mesons in the chiral limit in the model turns out in correspondence with description in terms of chiral Lagrangian for pions in QCD.
116301993
Quasi-stable states in the physical spectrum of the Neveu-Schwarz dual model
A certain class of states, comprising most of the spectrum for large mass M, is distinguished in the spectum of physical states predicted by the Neveu-Schwarz dual model with intercepts ..cap alpha../sub rho/(0) =1 and ..cap alpha../sub ..pi../(0) =1/2. The massive particles with large spins in this class are quasi-stable. Their couplings with all the other states are of order M/sup -1/ in comparison with the ordinary vertices. For the critical dimensions D=10 these states coincide with the zero-norm spurions. For the anomalous dimensions D=9 some of the quasi-stable states become new zero-norm spurion states. (AIP)