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First Results of the Phase II SIMPLE Dark Matter Search

M. Felizardo, T. Morlat, A. C. Fernandes, TA Girard, J. G. Marques, A. R. Ramos, M. Auguste, D. Boyer, A. Cavaillou, C. Sudre, J. Poupeney, R. F. Payne, H. S. Miley, J. Puibasset

TL;DR

These results yield a limit of |a(p)|<0.32 for M(W)=50 GeV/c² on the spin-dependent sector of weakly interacting massive particle-nucleus interactions with a 50% reduction in the previously allowed region of the phase space, formerly defined by XENON, KIMS, and PICASSO.

Abstract

We report results of a 14.1 kgd measurement with 15 superheated droplet detectors of total active mass 0.208 kg, comprising the first stage of a 30 kgd Phase II experiment. In combination with the results of the neutron-spin sensitive XENON10 experiment, these results yield a limit of |a_p| < 0.32 for M_W = 50 GeV/c2 on the spin-dependent sector of weakly interacting massive particle-nucleus interactions with a 50% reduction in the previously allowed region of the phase space formerly defined by XENON, KIMS and PICASSO. In the spin-independent sector, a limit of 2.3x10-5 pb at M_W = 45 GeV/c2 is obtained.

First Results of the Phase II SIMPLE Dark Matter Search

TL;DR

These results yield a limit of |a(p)|<0.32 for M(W)=50 GeV/c² on the spin-dependent sector of weakly interacting massive particle-nucleus interactions with a 50% reduction in the previously allowed region of the phase space, formerly defined by XENON, KIMS, and PICASSO.

Abstract

We report results of a 14.1 kgd measurement with 15 superheated droplet detectors of total active mass 0.208 kg, comprising the first stage of a 30 kgd Phase II experiment. In combination with the results of the neutron-spin sensitive XENON10 experiment, these results yield a limit of |a_p| < 0.32 for M_W = 50 GeV/c2 on the spin-dependent sector of weakly interacting massive particle-nucleus interactions with a 50% reduction in the previously allowed region of the phase space formerly defined by XENON, KIMS and PICASSO. In the spin-independent sector, a limit of 2.3x10-5 pb at M_W = 45 GeV/c2 is obtained.

Paper Structure

This paper contains 1 equation, 4 figures.

Figures (4)

  • Figure 1: Scatter plot of the squared amplitude and frequency of the primary harmonic of each true nucleation event (solid), together with the same for neutron and $\alpha$ calibration events (open), with the dashed horizontal line corresponding to a signal amplitude of 100 mV.
  • Figure 2: A typical histogram of calibration neutron and $\alpha$ amplitudes, each population consisting of several hundred events. The vertical dashed line indicates the neutron discrimination cut at A $\leq$ 100 mV, which includes all neutron calibration events.
  • Figure 3: a$_{p}$-a$_{n}$ for SIMPLE at M$_{W}$ = 50 GeV/c$^{2}$ , together with benchmark experiment results; the dashed contour represents a "0 evt" SIMPLE result for the same exposure. The allowed regions are defined by a band (single nuclei target) or ellipse (multinuclei target), with the external area excluded. The cross-hatched central area about (0,0) indicates the region allowed by this result and XENON.
  • Figure 4: Spin-independent contour for SIMPLE; the dashed contour represents a "0 evt" SIMPLE result for the same measurement exposure. Also shown are several picnote of the leading spin-independent search results; the shaded area represents the recent result of CoGeNT cogent.