The SIMPLE Phase II Dark Matter Search
| Title: | The SIMPLE Phase II Dark Matter Search |
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| Authors: | Felizardo, M., Girard, TA, Morlat, T., Fernandes, A. C., Ramos, A. R., Marques, J. G., Kling, A., Puibasset, J., Auguste, M., Boyer, D., Cavaillou, A., Poupeney, J., Sudre, C., Carvalho, F. P., Prudencio, M. I., Marques, R. |
| Publication Year: | 2014 |
| Collection: | High Energy Physics - Phenomenology Physics (Other) |
| Subject Terms: | High Energy Physics - Phenomenology, Physics - Instrumentation and Detectors |
| More Details: | Phase II of SIMPLE (Superheated Instrument for Massive ParticLe Experiments) searched for astroparticle dark matter using superheated liquid C$_{2}$ClF$_{5}$ droplet detectors. Each droplet generally requires an energy deposition with linear energy transfer (LET) $\gtrsim$ 150 keV/$\mu$m for a liquid-to-gas phase transition, providing an intrinsic rejection against minimum ionizing particles of order 10$^{-10}$, and reducing the backgrounds to primarily $\alpha$ and neutron-induced recoil events. The droplet phase transition generates a millimetric-sized gas bubble which is recorded by acoustic means. We describe the SIMPLE detectors, their acoustic instrumentation, and the characterizations, signal analysis and data selection which yield a particle-induced, "true nucleation" event detection efficiency of better than 97% at a 95% C.L. The recoil-$\alpha$ event discrimination, determined using detectors first irradiated with neutrons and then doped with alpha emitters, provides a recoil identification of better than 99%; it differs from those of COUPP and PICASSO primarily as a result of their different liquids with lower critical LETs. The science measurements, comprising two shielded arrays of fifteen detectors each and a total exposure of 27.77 kgd, are detailed. Removal of the 1.94 kgd Stage 1 installation period data, which had previously been mistakenly included in the data, reduces the science exposure from 20.18 to 18.24 kgd and provides new contour minima of $\sigma_{p}$ = 4.3 $\times$ 10$^{-3}$ pb at 35 GeV/c$^{2}$ in the spin-dependent sector of WIMP-proton interactions and $\sigma_{N}$ = 3.6 $\times$ 10$^{-6}$ pb at 35 GeV/c$^{2}$ in the spin-independent sector. These results are examined with respect to the fluorine spin and halo parameters used in the previous data analysis. Comment: 20 pages, 19 figures; accepted Physical Review D |
| Document Type: | Working Paper |
| DOI: | 10.1103/PhysRevD.89.072013 |
| Access URL: | http://arxiv.org/abs/1404.4309 |
| Accession Number: | edsarx.1404.4309 |
| Database: | arXiv |
| DOI: | 10.1103/PhysRevD.89.072013 |
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