Status of Dark Matter Detection Experiments

Transcription

1 Status of Dark Matter Detection Experiments Debasish Majumdar Astroparticle Physics and Cosmology Division Saha Institute of Nuclear Physics Kolkata

2 WIMP Hunting Going beyond gravity, three ways to detect WIMPs WIMP pair production at hadron colliders χ f χ f Indirect detection of radiation from pair annihilation Direct detection of WIMP scattering off a nucleus Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 2

3 Detection of Dark Matter Direct Detection Rotation of galactic disc through the halo of Dark Matter causes the earth to experience an apparent wind of Dark Matter Elastic collision of WIMP with detector nuclei The recoil energy of the nucleus is measured (phonon, ionisation and scintillation) Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 3

4 Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 4

5 Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 5

6 Types of Direct Detection 1.Spin Independent (SI) ground state spin of detecting nucleus is zero 2.Spin Independent (SD) ground state spin of detecting nucleus is non-zero Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 6

7 Differential detection rate of Dark Matter per unit detector mass NT denotes the number of target nuclei per unit mass of the detector Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 7

8 s 1 fm Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 8

9 Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 9

10 Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 10

11 The WIMP-nucleus scattering interaction loses its coherence when the de Broglie wavelength λ (corresponding to the momentum transfer) becomes greater than the nuclear size. The coherence is lost when Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 11

12 Dark Matter Direct Detection Experiments Dark Matter-nucleus elastic scattering Recoil of target nucleus is measured Recoil energy is very low, ~ few kev Low threshold detector is required Dark Matter-electron scattering (recent) Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 12

13 Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 13

14 Phonon is a collective excitation of the crystal in which the periodic arrangement in the crystal is set to vibrational mode (normal mode) at a single frequency. The resulting phonon vibration increases the temperature of the crystal which is measured. Scintillation is a phenomenon in which the incident particles or photons excite atoms or molecules in the ground state and the light is reemitted when the atom comes down to the initial state again in other words the absorbed enegy is reemitted (luminescence). In the Ionisation process, the target atoms are ionised by the recoil energy. Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 14

15 Heavier dark matter searches through direct detection experiments yielded none result so far The search was for heavier DM (few tens of GeV). Presently the interest has shifted for lower mass DM (sub GeV to few GeV) Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 15

16 Possibilities of lighter target mass Low Threshold Dark Matter scattering with electron Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 16

17 Experimental Challenges WIMPs: Extremely small scattering rate, small energy of the recoiling nucleus, and subtle signatures Requirements: Low (kev) energy threshold Large target mass Suppression of backgrounds from radioactivity and cosmic rays (α,β,γ, neutrons) Deep sites Passive/active shielding Discrimination of residual background Use WIMPS signatures WIMPs Signatures: Nuclear recoils, not electron recoils Absence of multiple scattering Annual modulation Directionality Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 17

18 Direct detection experimental details Discrimination Name Location Technique Material Status CUORICINO Gran Sasso Heat 41 kg TeO 2 running None Statistical Event-byevent GENIUS-TF Gran Sasso Ionization 10 to 40 kg Ge in N 2 running??? HDMS Gran Sasso Ionization 0.2 kg Ge diodes stopped IGEX Canfranc Ionization 2 kg Ge Diodes stopped DAMA Gran Sasso Light 100 kg NaI stopped LIBRA Gran Sasso Light 250 kg NaI running NaIAD Boulby mine Light 46 kg NaI stopped ZEPLIN-I Boulby mine Light 4 kg Liquid Xe stopped XENON Surface to GS Light+ Ionization 3 to 10 kg Liquid Xe running ZEPLIN II Boulby mine Light+ Ionization 6 kg Liquid Xe running CDMS-I Stanford Heat + Ionization 1 Kg Ge Kg Si stopped CDMS-II Soudan mine Heat + Ionization 2 to 7 kg Ge to 1.4 Kg Si running CRESST-I Gran Sasso Heat + Light kg Al 2 O 3 stopped CRESST-II Gran Sasso Heat + Light 0.6 to 9.9 kg CaWO 4 running EDELWEISS-I Modane Heat + Ionization 1 kg Ge stopped EDELWEISS-II Modane Heat + Ionization 10 to 30 kg Ge In istallation PICASSO SNO Bubble chamber 20 g Freon running ROSEBUD Canfranc Heat + Light 50 g Al 2 O g Ge + 54 g CaWO 4 running Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 18

19 Liquid Xenon Xe (A = 131.3) gives a high signal cross section σ A kg-year exposure can probe cm 2 Attractive liquid Xe properties High density: 3 g/cm 3 Compact detector Boiling point: 165 K is warmer than liquid N 2 (77 K) Simpler cryogenics Liquid Ar is 87 K. Ge (CDMS) is 10 mk Good scintillator: 42 photons/kev at 175 nm PMTs have good (~30%) quantum efficiency at this wavelength Ar scintillates at 128 nm Need wavelength shifter High ionization yield: 64 electron-ion pairs/kev Short radiation length: 2.77 cm Self shielding Background γ rays and neutrons cannot reach the fiducial volume Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 19

20 Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 20

21 Kamioka Underground Lab, Japan Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 21

22 Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 22

23 XMASS result (2018) ArXiv: [astro-ph.co] Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 23

24 LUX Detector Located at Sanford Lab at Davis 4850 feet (1478 m) underground Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 24

25 LUX result (2017) Phys. Rev. Lett. 118, (2017) Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 25

26 Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 26

27 Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 27

28 Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 28

29 XENON 1T result (2017) Laboratori Nazionali del Gran Sasso in Italy ~2000 kg target mass of dual-phase Xe detector (sci. & ion.) Phys. Rev. Lett. 119, (2017) Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 29

30 CRESST-III result (2017) Target CaWO4 Threshold < 100 ev Low DM mass region (sub-gev) ArXiv: [astro-ph.co] Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 30

31 CDMS (Cryogenic Dark Matter Search) at SOUDAN mines The CDMS II experiment looks for heavy, slow moving WIMPs using unique ZIP detectors. The detectors are hockey puck-sized disks of silicon and germanium, kept cold by a special cryogenic apparatus at about.04 degrees K. Each 250g germanium or 100g silicon crystal provides two sets of information about interactions with incident particles. When the incident particle, perhaps a WIMP, hits the nucleus of an atom in the detector it generates vibrations called phonons. The phonons are detected by thin films of tungsten metal. These phonons travel to the opposite side of the detector. Each 250g germanium or 100g silicon crystal provides two sets of information about interactions with incident particles. Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 31

32 When the incident particle, perhaps a WIMP, hits the nucleus of an atom in the detector it generates vibrations called phonons. The phonons are detected by thin films of tungsten metal. These phonons travel to the opposite side of the detector. As the phonon travels to the opposite side it excites the electrons in thin aluminum films. This energy is transferred to the tungsten which is biased with some electrical energy already; the energy pushes it right near the brink of going through a transition from being a superconductor to a closer to normal conductor. Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 32

33 The Zip detectors are placed in a container called a cryostat. The cryostat is constructed of radiopure copper, ensuring a lowradioactivity environment for the extremely sensitive CDMS detectors. Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 33

34 Ge detector Soudan Underground Lab Phonon Signal Sensitivity for WIMP masses < 10 GeV Achievable threshold as low as 56 evee CDMSlite result (2018) Phys. Rev. D 97, (2018) Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 34

35 PandaX-II result (2017) 580 kg dual-phase xenon time-projection chamber WIMP > 100 GeV Phys. Rev. Lett. 119, (2017) Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 35

36 PandaX-II result on Axion electron coupling (2017) Phys. Rev. Lett. 119, (2017) Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 36

37 PICASSO PICASSO at SNOLAB uses CS2 gel (Superheated droplet) Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 37

38 PICASSO / PICO Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 38

39 Other Detectors DRIFT Detector Located at Boulby mines (1100 metre deep) at Great Britain. Uses low pressure elctronegative CS2 gas as detector material Drifts CS2 ions instead of free electrons Enables discrimination of directional events Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 39

40 NEWAGE (New generation WIMP search with an advanced gaseous tracker experiment) Detector Located at Japan Uses CF4 gas at 150 Torr. Direction sensitive micro TPC detector CoGeNT at Soudan mines uses Ge DAMA at Gran Sasso uses NaI SIMPLE at France uses C2ClF5 droplets (Superheated droplet) Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 40

41 Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 41

42 Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 42

43 Indian Endeavour in DM Search Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 43

44 Dark INO (DINO) Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 44

45 2/02/18 5 Dark-matter@INO (DINO) Ton-scale 2020 INO Lab Depth 1.3km Pottipuram in Bodi West hills

46 2/02/18 6 JADUGUDA MINE ELEVATION DRAWING 165 m New proposed site Bypass to ore bin 495 m 555 m 500 m Uranium mining on 880 m Debasish Majumdar, S.I.N.P.

47 2/02/18 7

48 2/02/18 8

49 2/02/18 9 Underground Neutron Flux (Mei & Hime) Debasish Majumdar, S.I.N.P.

50 2/02/18 0

51 THANK YOU Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 51

52 Distinguishing electron and neutron background Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 52

53 Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 53

54 Nu HoRIzons VII, HRI, Debasish Majumdar, S.I.N.P. 54