IPRD 2016 IPRD Light Dark Matter searches at LSM, Modane and SNOLab. Ioannis KATSIOULAS CEA, Saclay / IRFU / SEDI.

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1 IPRD 2016 IPRD 2016 Light Dark Matter searches at LSM, Modane and SNOLab Ioannis KATSIOULAS CEA, Saclay / IRFU / SEDI ioannis.katsioulas@cea.fr

2 New Experiments With Spheres AIM: Search for WIMPs in the 100 MeV 10 GeV Motivation: Non findings at: Passive experiments LHC Spin Independent couplings Method: Direct detection using: Novel gaseous proportional counter (SPC) Light gases as target (H, He, Ne)

3 Spherical Proportional Counter - Spherical TPC Historical elements Old LEP RF cavities Spherical gaseous detectors In picture: I.Giomataris G.Charpak

4 SPC-Principal of operation Greatly inhomogeneous field along the radius E = V 0 r 2 r 1 r 2 r 2 - r 1» V 0 r 2 r 1 r 1 = anode radius r 2 = cathode radius Natural division of the volume in two Drift volume Multiplication volume I.Giomataris et al,jinst,2008, P09007

5 Induced Pulses Pulse Shape Analysis Parameters Inverted Tail Pulse Parameters Baseline Noise Peak amplitude Rise time Width Integral Number of peaks Informations are hiding in the pulse shape and its characteristics

6 Illustration of particle identification Background rejection Rise time ( s) Run with Ar/CH 4 + 3g mb SPC 130cm LSM Tracks 5.9 kev X-Rays 210 Po 5.3 MeV 210 Po 5.3 MeV from 210 Cu surface Range = 15 cm Rate 400 capt/d n capt on 3 He 764 kev n capt on 3 He => p + T PL Rn 218 Po 214 Po Point like Amplitude Recoils from fast neutron expected here «Volume» alpha 6

7 Capacitance dependence on size Micromegas GEM Parallel Plate Detector C S > 1nF Cylindrical Proportional Counter C =2pL/ln(b/a)>> 10 pf Spherical Proportional Counter C r 1 < 1pF

8 Low energy capabilities - Calibration Single electron detection Energy threshold < 50 ev SPC Φ 130 cm Detection of fluorescence X-rays 241 Am 237 Np+ 4 He+ 5.6 MeV Lines Al -> 1.45 kev Cu -> kev 237 Np -> kev(l α ) kev(l β ) 5.9 kev SPC Φ 40 cm Irradiation by an 55 Fe source (5.9 kev) Energy resolution ~ 9 %

9 SPCs around the world Low background detector d=60 cm P=10 bar Basic detector in Saclay University of Saragoza detector University of Thessaloniki detector Queens University test sphere University of Tsinghua - HEP detector Different sizes Different Materials Different Applications

10 SPC-Summary Large target mass Construction from radiopure materials (Low BG) Very low energy threshold Good energy resolution Low noise (low capacitance) Single read out Simple and robust Easy maintenance Fiducialization-Background rejection capabilities Flexibility in gas choice (H, He, Ne, Ar, Xe, N 2 ) Flexibility in material Flexibility in operating pressure

11 Prototype low background SPC at LSM, Modane A testing ground for NEWS Copper vessel equipped with 6.3 mm Ø sensor Gas: Ne+0.7%CH 3.1 bars Sensitive mass: 310 gr Chemically cleaned several times for Radon deposit removal Laboratoire Souterrain de Modane Shielding 03/10/2016

12 Main background (BG) sources for LSM detector 60 Co Contamination of 1 mbq/kg 210 Pb, 210 Bi Contamination of 1 nbq/kg BG Rate = evnt/kev/kg/day BG Rate = evnt/kev/kg/day Solution: Limit time exposure on ground for pure copper. Solution: Chemical cleaning Effect of cleaning: High energy events 180 mhz => ~2 mhz Low energy events 400 mhz => ~20 mhz First cleaning Second cleaning Amplitude spectra before and after cleaning.

13 Operation and data taking conditions Data taking continuously during 42 days with: Use of 3.1 bar gas mixture 99.3% Neon % CH 4 High voltage on the sensor set to 2520 V, no sparks Absolute Gain around Seal mode, no recirculation. Loss of gain 4% along 42 days monitored with 210 Po line. Variation of ± 4% on daily scale. Amplifier Canberra 2006 (RC=50 μs) Calibrations in energy with 37 Ar gaseous source (from (n,a) reaction of 40 Ca)

14 Simulation of the detector responce Anticipated main backgrounds: Compton electrons (volume) 210 Pb decay products (surface) LSM detector Pulse simulations include: Radial field Diffusion (Magboltz) Current induction Preamplifier delta response Thessaloniki detector 5.9 kev X-rays used for calibration Analysis threshold : 150 ev

15 Comparison of simulation with neutron calibration measurements with an Am-Be source with Am-Be source on site In good agreement

16 Expected sensitivity of the experiment ROI: region where we expect the maximum component of WIMP signal Prediction of Energy vs Rise time in Region Of Interest (ROI) from the population of Surface and Compton events. Limit set on spin independent coupling WIMPs with standard assumptions on WIMP velocities, escape velocity and with quenching factor of Neon nuclear recoils in Neon calculated from TRIM/SRIM

17 35 t shields Implementation at SNOLAB by fall cm Ø detector, 10 bars, Ne, He, CH 4 Low BG Copper Shell Shield: Compact -ancient- Lead + PE Lead shield Copper sphere PE shield 6000 m.w.e

18 Background (simulation) Ne He H

19 Predicted exclusion limits for NEWS

20 Collaboration Queen s University Kingston G.Gerbier, P di Stefano, R. Martin, T. Noble, B. Cai, A. Brossard, A. Kamaha, P. Vasque, Q. Arnaud, K. Dering, J. Mc Donald, M. Clark and summer students Copper vessel and gas set-up specifications, calibration, project management Gas characterization, laser calibration, on smaller scale prototype Simulations/Data analysis IRFU/Saclay -I. Giomataris, M. Gros, I. Katsioulas, T. Papaevangelou, A. Gigagnon, JP.Bard, JP. Mols, XF. Navick, Sensor/rod (low activity, optimization with 2 electrodes) Electronics (low noise preamps, digitization, stream mode) DAQ/Software LSM (Laboratoire Souterrain de Modane) - F Piquemal, M Zampaolo, A DastgheibiFard Low activity archeological lead for close electronics/valve shield Coordination for lead/pe shielding and copper sphere Thessaloniki University I Savvidis, S. Tzamarias, A. Leisos, C. Elefteriadis, A. Liolios Simulations, neutron calibration Studies on sensor LPSC Grenoble D. Santos, JF. Muraz, O. Guillaudin Quenching factor measurements < 1 KeV with ion beams TU Munich A Ulrich Gas properties and ionization process for Penning mixtures Pacific National Northwest Lab E Hoppe Low activity measurements, Copper electroforming Associated lab : TRIUMF - F. Retiere light detection, sensor Oct 2016

21 THANK YOU