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NEWS: measurements at sub keV energies with spherical detectors G Gerbier + I Giomataris, J Derre, P Magnier, A Dastgheibi, D. Jourde, M Gros, E Bougamont,

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Presentation on theme: "NEWS: measurements at sub keV energies with spherical detectors G Gerbier + I Giomataris, J Derre, P Magnier, A Dastgheibi, D. Jourde, M Gros, E Bougamont,"— Presentation transcript:

1 NEWS: measurements at sub keV energies with spherical detectors G Gerbier + I Giomataris, J Derre, P Magnier, A Dastgheibi, D. Jourde, M Gros, E Bougamont, XF Navick, T Papaevangelou, J Galan, G Tsiledakis IRFU–Saclay on behalf of NEWS collaboration Introduction to the detector Low energy investigations -preliminary- Calibrations, characterisation Measurements at LSM NEWS : neutrino coherent scattering measurement 6th TPC Symposium- Paris

2 Drift region Ampl region Spherical Proportional Counters Sphere cavity + spherical sensor + HT Low threshold (low C) Fiducial selection by risetime Flexible (P, gaz) Large mass / large volume Robust, simple, cheap, sealed mode 1 MHz, soft trigger 2 LEP cavity 130 cm Ø tested 1 low activity 60 cm Ø in LSM 2

3 Run with Ar/CH 4 + 3g mb SPC 130cm LSM Rise time ( s) Amplitude 210 Po 5.3 MeV n capt on 3 He 764 keV 222 Rn 218 Po 214 Po If localised energy deposition, rise time depends of radius (diffusion) If track, rise time depends on orientation of track (different drift times) NB: no start => risetime records place and/or history of energy deposition derivative alpha de/dx 3

4 Rise time ( s) Amplitude 210 Po 5.3 MeV n capt on 3 He 764 keV 210 Po 5.3 MeV from 210 Cu surface R = 15 cm n capt on 3 He => p + T 222 Rn 218 Po 214 Po Unwanted Radon daughter deposit on surface : fast neutron expected here Taux 400 capt/j Run with Ar/CH 4 + 3g mb SPC 130cm LSM 4

5 Calibrations with (external) sources Saclay SPC, Ar/CH4, 500 mb, 16 mm ball Calibration with 22 keV from 109Cd => Illustration of volume/surface identification 8.1 keV from fluorescence of Cu 22 keV 8 keV Volume interactions Latt 22 keV= 190 cm Latt 8 keV= 10 cm Periph interactions 5

6 Calibration with UV flash lamp for single electron response Digitised region around where UV induced pulse expected => Look for pulse in s window About 1 in 10 => single electron response 10 ADU => Trigger efficiency for single electron = 54 % 1 electron 16 ADU s Single electron distribution 250 mb, Ar/2%CH4 6

7 37 Ar, 35 days lifetime, K 2.6 keV and L 260 ev Can be made with Calcium irradiated with fast neutrons => first experiments successful ! Volume calibration with 37 Ar source Behaviour at E<300 eV 2.6 keV 7

8 Spectrum at low energy in surface lab adu 20 eV thresh 600 eV Exponential rise at low energy Saclay Ar/2%CH4 250 mb 10 6 evts/keV.d 8

9 Spectrum at low energy in surface lab adu Simulated spectrum shape with flat electron mean exponential => Source of single electrons ? Many… 600 eV 20 eV thresh 9

10 Detecting coherent neutrino scattering ? Simulation of expected spectrum from nuclear reactor, on Ar, with quenching factor and instrumental response Normalisation to experimental reactor 70 MW Sphere of 2 m diam, 5 bars 20 ev/keV.kg.d 80 ev/keV.kg.d >30 eV 30 eV Equivalent to 120 days exposure If background is 500 evts/kg.d.keV Nbackev= 500*37*120*0.22= evts S/N = 1/20, N = 30 eV 10

11 Data with « SEDINE » the 60 cm low activity LSM Argon 39 (1 Bq/kg) Alphas (Po Rn induced) In shield Tot rate surface Tot Ar CH4(2%) SPC 130 cm Pressure mb Rate Hz Residual e rate 11

12 Data with « SEDINE » the 60 cm low activity LSM Stability of gain : 4 days ok 12

13 Data with « SEDINE » the 60 cm low activity LSM – « High energy » h 222 Rn 210 Po In volume ? in vol on surf in vol Corrected for gain loss (1 % in 4 days) Inventory of alpha rates Po210 peak Hz 1300/m2.d (« EDW » 400) Rn222 peak Hz Po214 peak Hz Po218 peak Hz Tail Hz « Bi-Po » event NB : 2009 measurement with 130 cm SPC => Hz Po210 Degasing of valves ? 218 Po 214 Po 13

14 Example of two 50 mb & 300 mb runs (<24h, non stable conditions) Data with « SEDINE » the 60 cm low activity LSM – « Low energy » Monte carlo simulations on going : see G Tsiledakis talk eV keV « Electron track » spectrum (high RT) evts/kev.d 23 keV 3 keV 300 mb 50 mb Localised energy deposition in volume Need volume calibration to estimate cuts and background level Need better estimator for rejection evts/kev.d 14

15 Detecting ALPs ? Axion Like Particles KK postulated to explain high temperature corona of sun (Zioutas/di Lella, v1) => should decay in 2 gammas with spectra < 3 rate = 200 /d/m 3 Analysis of pulse shape provide signature Tests runs in Saclay with 130 cm SPC on-going derivative Pulse of 6 keV 55 Fe source Working on background rejection and simulation : J Galan and T Papaevangelou GG IG a1/a2 a1 a2 15

16 CEA-IRFU/Saclay (GG,IG),LSM (F Piquemal), Aristotle University of Tessaloniki (I Savvidis), University of Ioannina (I Vergados), NCSR DemoKritos (G Fanourakis), Hellenic Open University (S Tzamaria) University of Tsinghua Beijing (C Tao), Shanghai Jiao Tong University (K Ni), IHEP-Beijing ( C Yang) University of Saragoza (I Irastorza), Livermore (JR Armendariz) New Experiments With Spheres Neutrino Experiments With Spheres New Experiments for Wimps with Spheres F : R&D at Saclay and LSM, sensors, high P F : Coherent neutrino scattering experiment feasibility (ERC submitted by IG/GG) G : Neutron monitor (I Savvidis next talk) C : R&D with SPC 130 cm shipped to Beijing, investigating large sphere building / tests F G C : SN monitor, DM … Tessaloniki


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