The COSINUS project. development of new NaI- based detectors for dark ma6er search. STATUS report Karoline Schäffner

Transcription

1 The COSINUS project development of new NaI- based detectors for dark ma6er search STATUS report 2016 Karoline Schäffner

2 SCATTERING SCENARIO Dark matter particles scatter off nuclei elastically coherently: ~A 2 spin-independent Pictures source: CSN5 meeting in Lecce - K. Schäffner 2

3 DIFFERENTIAL SCATTERING RATE Prepare detector for: dn/de / [1/(keV kg d pb)] GeV/c 2 WIMP spectrum in NaI Energy [kev] very small energy deposits ( few kev - tens of kev) extremely rare detection rate (few events per ton per year) signal embedded in a background that is millions of times higher CSN5 meeting in Lecce - K. Schäffner 3

4 SODIUM IODIDE AS TARGET (NaI) MOTIVATION: multi-target compound: light Na and heavy I 11 Na 53 I positive evidence for the presence of DM particles in the galactic halo supported at 9.3σ C.L. by the DAMA/LIBRA experiment using NaI (Tl) as scintillation detector CSN5 meeting in Lecce - K. Schäffner 4

5 The COSINUS R&D project Eur. Phys. J. C (2016) 76:441 DOI /epjc/s CSN5 meeting in Lecce - K. Schäffner 5

6 SCINTILLATING CALORIMETER heat bath 10 mk Phonon signal (~ 96 %) weak thermal coupling thermometer (almost) independent of particle type crystal precise measurement of the deposited energy particle interaction temperature rise T CSN5 meeting in Lecce - K. Schäffner 6

7 SCINTILLATING CALORIMETER heat bath 10 mk Phonon signal (~ 96 %) weak thermal coupling thermometer (almost) independent of particle type crystal precise measurement of the deposited energy particle interaction temperature rise T scin9lla9on light Scintillation light (~ 4 %) amount of emitted light depends on particle type à LIGHT QUENCHING discrimination of interacting particle via the ratio light to phonon signal à LIGHT YIELD CSN5 meeting in Lecce - K. Schäffner 7

8 COSINUS detector design NaI Target Crystal scintillator multi-element target mass: ~ g 11 Na 53 I CSN5 meeting in Lecce - K. Schäffner 8

9 COSINUS detector design CdWO 4 carrier crystal carries the W-TES silicon oil as interface mass: ~ 13 g Silicon oil CdWO CSN5 meeting in Lecce - K. Schäffner 9

10 COSINUS detector design Light absorber Silicon beaker shape ~ 40 mm diameter & height CdWO 4 High Purity silicon CSN5 meeting in Lecce - K. Schäffner 10

11 COSINUS detector design Light absorber Silicon ~ 40 mm diameter & height fully active veto à reject alpha-induced bckg. à high light collection efficiency CdWO 4 copper detector holder 210 Po 206 Pb (103 kev) + α (5.3 MeV) bulk contamination with 210 Po CSN5 meeting in Lecce - K. Schäffner 11

12 COSINUS detector design Silicon TES 2 independent channels W-TESs as thermometers simultaneous readout of à phonon signal in NaI à scintillation light CdWO 4 TES CSN5 meeting in Lecce - K. Schäffner 12

13 COSINUS detector design Particle discrimination TES Silicon simultaneous detection of: energy in the crystal E scintillation light L discrimination of interacting particle via the ratio L/E CdWO 4 TES I L e/γ Na E I CSN5 meeting in Lecce - K. Schäffner 13

14 COSINUS detector design Silicon TES Performance goal NaI detector: Nuclear recoil energy threshold ~ 1 kev energy resolution σ=200 ev CdWO 4 TES light detector: noise of baseline σ 10 ev 4% of deposited energy detected in light Eur. Phys. J. C (2016) 76:441 DOI /epjc/s bring performance in-line with existing bolometers e.g. produced within CRESST-II CSN5 meeting in Lecce - K. Schäffner 14

15 Light yield LIGHT YIELD = LIGHT SIGNAL HEAT SIGNAL L e/γ L/E e/γ Na Na I E I I E CSN5 meeting in Lecce - K. Schäffner 15

16 Simulated data for 100 kg days LIGHT YIELD = LIGHT SIGNAL HEAT SIGNAL Light Yield K contribution (600µBq) and flat background 1c/(keV kg d) DAMA/LIBRA 2-6 kev ee - e /γ-band pink colored boxes correspond to DAMA/LIBRA signal regions in the standard elastic scattering scenario WIMP events from simulation Na-recoils I-recoils Energy (kev) Energy # Events Fraction 1-2 kev % 2-6 kev % > 6 kev 46 2 % TOTAL % Eur. Phys. J. C (2016) 76:441 DOI /epjc/s CSN5 meeting in Lecce - K. Schäffner 16

17 COMPARISON DAMA/LIBRA 2-6 kev ee Eur.Phys.J. C (2008), arxiv: COSINUS Light Yield K contribution (600µBq) and flat background 1c/(keV kg d) - e /γ-band DAMA/LIBRA 2-6 kev ee Eur. Phys. J. C (2016) 76:441 DOI /epjc/s WIMP events from simulation Na-recoils I-recoils Energy (kev) CSN5 meeting in Lecce - K. Schäffner 17

18 STATUS 09/ CSN5 meeting in Lecce - K. Schäffner 18

19 MILESTONES 2016 Detector parts Infra- structure Electronics DAQ Analysis Proof of Principle test CSN5 meeting in Lecce - K. Schäffner 19

20 DETECTOR PARTS Detector parts NaI crystals: commercial crystals for prototype testing from Hilger crystal company small commercial crystal for accelerator measurement arrived at LNGS trip to US last week to discuss on radiopure crystals from RMD Si- light absorbers: beaker-shape finalized and order placed to OPTEC company for manufacturing 3 beakers within next two months Carrier crystals: two CdWO 4 carriers with standard TES produced and ready at LNGS TES design: new ideas on TES with higher carrier-absorber discrimination preparation for first test runs ongoing CSN5 meeting in Lecce - K. Schäffner 20

21 INFRASTRUCTURE Infra- structure Upgrade of test cryostat: extension of the inner vacuum chamber and shields completed and tested mounting of new wiring for COSINUS-like SQUIDs scheduled for October COSINUS space in Hall A at LNGS: LNGS is still working in setting up the space for us space will house: glove box for detector assembling and NaI handling laminar flow box for detector mounting and bonding of TES mechanical working space tools CSN5 meeting in Lecce - K. Schäffner 21

22 ELECTRONICS and DAQ Electronics DAQ SQUID electronics: SQUID probes and electronics from Magnicon company à order procedure started VME-based DAQ components**: transient digitizer from INCAA à order procedure started crate controller from Struck à order procedure started crate à still to be ordered Heater-/Bias modules à in-home production à extra slide **software (~ lines) for detector operation and DAQ can be used as from CRESST-MPP à thanks to F. Pröbst!! CSN5 meeting in Lecce - K. Schäffner 22

23 HEATER BIAS MIB Electronics DAQ general meeting in April at MPP layout of first modules for pulsers now settled order for boards placed last week à presently in production at MIB request for 2017: transfer money to MIB to allow them to independently place the necessary orders involved people: Gianluigi Pessina, Paolo Carniti, Lorenzo Cassina, Claudio Gotti and Matteo Maino CSN5 meeting in Lecce - K. Schäffner 23

24 ASSEMBLY of first PROTOTYPE Proof of Principle test Light detector SOS TES NaI 55 Fe source CdWO 4 TES Silicon oil Thermal link F. Reindl et al. NEUTRINO conference 2016, London Proceedings in preparation CSN5 mee9ng in Lecce - K. Schäffner 24

25 NaIce1 DETAILS NaI characteristics: (20x30x30) mm 3 equals to about 66 g all sides perfectly polished from Hilger crystal company 55 Fe source on lateral side NaI crystal CdWO 4 carrier crystal: small standard TES 1.5 mm thickness, 40 mm diameter about 13 g Light detector: SOS light absorber a là CRESST sep. heater and 55 Fe source CSN5 mee9ng in Lecce - K. Schäffner 25

26 MOUNTING IN THE CRYOSTAT 5 cm of Pb to shield radioac9vity from the dilu9on unit of the cryostat decoupling system to reduce microphonic noise cryostat cold from to Light detector NaI phonon detector copper housing CSN5 mee9ng in Lecce - K. Schäffner 26

27 PULSES FROM 60keV GAMMAS Pulses acquired in coincidence with the light detector and the NaI detector a]er the absorp9on of a 60 kev gamma from an 241 Am external calibra9on source. scin9lla9on light signal phonon/heat signal in NaI CSN5 mee9ng in Lecce - K. Schäffner 27

28 Pulse as recorded in the NaI crystal Pulse can be described by the standard model for cryogenic calorimeters from F. Pröbst et al., J. Low Temp. Phys. 100, 69 (1995) F. Pröbst et al., J. Low Temp. Phys. 100, 69 (1995) CSN5 mee9ng in Lecce - K. Schäffner 28

29 RAW but calibrated DATA Internal use only No cuts! Energy in the light detector [kev] Direct light detector hits carrier events Energy in the phonon detector NaI [kev] CSN5 meeting in Lecce - K. Schäffner 29

30 Preliminary scatter plot of NaIce1 Internal use only CSN5 meeting in Lecce - K. Schäffner 30

31 CONCLUSION and OUTLOOK COSINUS aims to develop first NaI detector with particle discrimination First NaI detector module successfully operated for about 3 month at LNGS à no unexpected detector artifacts à stable operation at about 10 mk à energy threshold of about 10 kev (preliminary) à proof that NaI works as scintillating calorimeter à calibration with neutrons from external neutron source (but VERY weak source) data analysis of NaIce1 measurement is ongoing, results in the next weeks for 2017: optimise, modify, investigate to improve threshold and energy resolution of the NaI detector ( new TES-design and interface solution ) measurement of quenching factors at the neutron beam at TUM in preparation CSN5 meeting in Lecce - K. Schäffner 31

32 THANK YOU! CSN5 meeting in Lecce - K. Schäffner 32