1. SIMPLE Tom Girard ( for the SIMPLE Collaboration )

2. SIMPLE gas 25  m 1 mm WIMP Superheated freon droplet (i) E > E c = 4  r c 2  /3  (ii)  E/  x > E c /ar c ( Seitz : Phys. Fluids 1 (1979) 1 )  E/  x  150 keV/μm intrinsic BG rejection < 10 -10 v-a-v bolometers: 10 -4,-5 xenon: 10 -2 argon: 10 -7,-8 key feature: selective sensitivity tunable (P,T) double threshold device

3. Instrumentation MCE-200 microphone true nucleation event PGA2500 adaptive amplifier 1 TB pcs (8 chl each), MatLab files of ~ 8 min (~ 4 MB) each SDD noise: 2-3 mV Δ  : 1.6 x10 -2 ms ΔV: 0.3 mV

4. Laboratoire Souterrain a Bas Bruit [LSBB]

5. GESA ( 60 m 3 ) 30-100 cm thick concrete 50-75 cm thick water (shield, pool) 20 cm thick wood 1 cm thick steel 50 cm thick concrete (floor) atmospheric radon: 20 – 3000 Bq/m 3 reduction : ventilation 10x per day top-circulation of waterpool (25 liter/min)

6. GESA backgrounds 232 Th (Bq/kg) 238 U (Bq/kg) 40 K (Bq/kg) concrete 7.7 11 57 steel 0.02 1. 8 0.02 water 7x10 -5 10 -4 -- 1.09 ± 0.02 ± 0.07 evt/kgd neutron :  : radon : air 0.36 Bq/m 3 0.0012 Bq/m 3 internal: < 0.71 evt/kgd (radioassay) water circulation ( 25 l/min )diffusion ( ,n) + sf + ( ,n) shielding muon : 8.6 x 10 2 m -2 d -1 3.26 ± 0.08 ± 0.76 evt/kgd

7.  stage I : 14.095 kgd ( arxiv:1003.2987v2 [astro-ph.CO] 22 Mar 2010 )  27 October -- 14 November 2009 : SDD installation, 1 per day ( +1.9 kgd )  15 November 2009 – 05 February 2010 ( 12.2 kgd ) data losses ( -4.70 kgd ) due to weather-induced power failures  stage II : ~18 kgd  12 April – 01 May 2010: SDD installation, 1 per day ( +1.9 kgd )  02 May – 22 July 2010: full complement ( +15.6 kgd ) no data losses Phase II

8. Signal analysis protocol:  accept all signals with amplitude > 2 mV over SDD noise (4056) ( efficiency  0.97 with 95% CL or better )  remove 2228 coincident signals ( efficiency  0.99 with 99% CL )  freon-less SDD  any other SDD  filter remaining 1828 signals wrt  signal waveform (amplitude, decay constant,...)  FFT structure (frequency, intensity distribution...)

9. Acoustics = ??  water inlet bubbles (40%)  SDD deck motion (15%)  electronic noise (5%)  SDD “Papa” noise (10%)  human noise (5%) .... NONE possess signal parameters or FFTs of true nucleation events  identification efficiency  97% at 95% CL  gel fractures (81 evt)  N2 release (63)  N2 escape (4%)  gel deterioration (10%) .... internalexternal

10. “MOST Wanted” Gallery ventilation cap knocking human noise pressure release water bubbles Fenwick motion microleak fracturetrapped N2 gas true

11. RESULTS : 1828 evts total => 60 true nucleation events “true” : = 450-750 Hz  = 5-40 ms

12. neutron and  calibrations 3.26 ± 0.48 evt/kgd consistent with sub-water radon level, SDD radiopurity 0.99 ± 0.28 evt/kgd consistent with MCNP 1.09 ± 0.02 ± 0.07 evt/kgd based on material radio-assays sound detection efficiency : 0.98 ± 0.03 E rth (9ºC) = 8.0 ± 0.1 keV ( acceptance  0.97 )

13. low amplitude sector = neutrons + WIMPS How many WIMPs possible ? neutrons observed : [14 ± 3.8 ] x (1/0.98) x (1/0.97) = 14.7 ± 4.0 evt neutrons estimated: 14.1 x [1.09 ± 0.02 ± 0.07] = 15.4 ± 0.28 ± 0.99 evt so  simple diff = -0.70 ± 4.1 evts  more conservative : ( max observed – min estimated ) evts expected ( [14.7 + 4.0] – [15.4 – 1.0] ) = 4.3 evt => up to 8 expected WIMPs at 90% CL

14. SD RESULTS (stage I)  SD ~ [ a p + a n ] 2 J -1 (J+1) = 0.441 ; = -0.109

15. SI RESULTS (stage I)

16. status & prospects  14.1 kgd completed ( 27/10 – 05/02, losses) > with XENON10, ~ 50% reduction in allowed SD phase space  + 18 kgd completed ( 01/05 – 22/07, no losses) – under analysis > reduce background subtraction : > less neutrons : xtra 10 cm wood, PE below waterpool  0.2 n / kgd > additional radio-assays of shielding, tank water... > prob’ly more  ’s (Summer radon  1000 Bq / m 3 ) > further refinements in signal analysis (hi-frequency component)

17. signal amplitudes neutron  “bang” “big bang” dE/dx temperature (ºC) N droplet diameter (  m) only this region capable of providing nucleation dE/dx

18. xtra

19. SI rate : ~ A 2 but there’s also F 2, arXiv:astro-ph/0703543