DM-Ice. A direct detection experiment for dark matter at the South Pole

Transcription

1 DM-Ice A direct detection experiment for dark matter at the South Pole Reina Maruyama on behalf of the DM-Ice Collaboration University of Wisconsin - Madison UCLA Dark Matter 2012 February 22-24,

2 Current Status of Bounds on Dark Matter from Terrestrial experiments 23

3 Current Status of Bounds on Dark Matter from Terrestrial experiments arxiv:

4 Current Status of Bounds on Dark Matter from Terrestrial experiments TAUP 2011 arxiv:

5 Current Status of Bounds on Dark Matter from Terrestrial experiments TAUP 2011 Aprile et al., arxiv: v1 (2011) arxiv:

6 Current Status of Bounds on Dark Matter from Terrestrial experiments TAUP 2011 Aprile et al., arxiv: v1 (2011) arxiv: arxiv:

7 Current Status of Bounds on Dark Matter from Terrestrial experiments TAUP 2011 Aprile et al., arxiv: v1 (2011) arxiv: arxiv: F. Petricca TAUP

8 Current Status of Bounds on Dark Matter from Terrestrial experiments TAUP 2011 Aprile et al., arxiv: v1 (2011) arxiv: arxiv: F. Petricca TAUP 2011 One claim for discovery: DAMA hints in CoGeNT? CRESST? 23

9 Are the Experimental Results Incompatible? Proposed sources for DAMA s annual modulation: Ambient temperature variation Muon flux depend on temperature/pressure in the upper atmosphere Spallation neutrons from muons in rock Radon diffusion from rocks may be varying with time Scintillator phosphorescence What about Detector Effects? quenching & channeling Threshold effects Astrophysical Uncertainties? f(v)? vesc? v0? co-rotating? streams? Which Dark Matter? *insert your favorite model here* 3

10 Are the Experimental Results Incompatible? Proposed sources for DAMA s annual modulation: Ambient temperature variation Muon flux depend on temperature/pressure in the upper atmosphere Spallation neutrons from muons in rock Radon diffusion from rocks may be varying with time Scintillator phosphorescence What about Detector Effects? quenching & channeling Threshold effects DAMA rules these out. See e.g. Belli s talk and arxiv: Astrophysical Uncertainties? f(v)? vesc? v0? co-rotating? streams? Which Dark Matter? *insert your favorite model here* 3

11 Are the Experimental Results Incompatible? Proposed sources for DAMA s annual modulation: Ambient temperature variation Muon flux depend on temperature/pressure in the upper atmosphere Spallation neutrons from muons in rock Radon diffusion from rocks may be varying with time Scintillator phosphorescence What about Detector Effects? quenching & channeling Threshold effects Astrophysical Uncertainties? f(v)? vesc? v0? co-rotating? streams? Which Dark Matter? or? Blum arxiv: DAMA rules these out. See e.g. Belli s talk and arxiv: *insert your favorite model here* 3

12 Are the Experimental Results Incompatible? Proposed sources for DAMA s annual modulation: Ambient temperature variation Muon flux depend on temperature/pressure in the upper atmosphere Spallation neutrons from muons in rock Radon diffusion from rocks may be varying with time Scintillator phosphorescence What about Detector Effects? quenching & channeling Threshold effects Collar Astrophysical Uncertainties? f(v)? vesc? v0? co-rotating? streams? Which Dark Matter? or? Blum arxiv: DAMA rules these out. See e.g. Belli s talk and arxiv: *insert your favorite model here* 3

13 Are the Experimental Results Incompatible? Proposed sources for DAMA s annual modulation: Ambient temperature variation Muon flux depend on temperature/pressure in the upper atmosphere Spallation neutrons from muons in rock Radon diffusion from rocks may be varying with time Scintillator phosphorescence What about Detector Effects? quenching & channeling Threshold effects Collar Astrophysical Uncertainties? f(v)? vesc? v0? co-rotating? streams? Which Dark Matter? or? Blum arxiv: DAMA rules these out. See e.g. Belli s talk and arxiv: *insert your favorite model here* 3

14 Are the Experimental Results Incompatible? Proposed sources for DAMA s annual modulation: Ambient temperature variation Muon flux depend on temperature/pressure in the upper atmosphere Spallation neutrons from muons in rock Radon diffusion from rocks may be varying with time Scintillator phosphorescence What about Detector Effects? quenching & channeling Threshold effects Collar Astrophysical Uncertainties? f(v)? vesc? v0? co-rotating? streams? Which Dark Matter? or? Blum arxiv: DAMA rules these out. See e.g. Belli s talk and arxiv: *insert your favorite model here* DAMA s signal deserves a close look and confirmation. 3

15 DM-Ice Objectives arxiv: Check the annual modulation observed by DAMA with... same detector material as DAMA: NaI(Tl) similar sensitivity and threshold completely different background 500 kg-yrs exposure 5-σ measurement Proposed location: South Pole Currently the only location with ready access in the southern hemisphere Same expected DM annual modulation phase Opposite seasons 2500 m overburden of ice Surrounded by clean H2O U/Th < 1 ppt, K < 1 ppb, minimal neutrons stable temperature, humidity, etc. Available infrastructure for science Muon veto by IceCube/DeepCore Sensitivity for NaI detectors with a 500 kg year running time (2-4 kev) with 1, 2, and 5 dru bgd.

16 DM-Ice Concept Detector kg NaI(Tl) Closely-packed inside pressure vessel for coincidence veto Two PMTs/Crystal local muon veto Location South Pole, ~ 2500 m deep in the ice Near the center of IceCube for additional veto Pressure vessel Withstand > 7000 psi of freeze-back pressure Low-background stainless steel Low background copper shielding where needed ~150 cm Electronics Pulse digitization inside the vessel Power from SP Station or IceCube Counting Lab Remotely controllable In-ice strings for DM-Ice deployment 5

17 Going to the South Pole

18 Amundsen-Scott South Pole Station Science and Facilities Amundsen-Scott South Pole Station runway runway IceCube IceCube Control Lab at the South Pole IceCube ARA South Pole South Pole South Pole with IceCube Amundsen-Scott South Pole Station AMANDA SPT, BICEP II

19 Amundsen-Scott South Pole Station Science and Facilities Amundsen-Scott South Pole Station runway runway IceCube IceCube Control Lab at the South Pole IceCube ARA South Pole South Pole South Pole with IceCube Amundsen-Scott South Pole Station AMANDA SPT, BICEP II

20 Amundsen-Scott South Pole Station Science and Facilities Amundsen-Scott South Pole Station runway runway IceCube IceCube Control Lab at the South Pole IceCube ARA South Pole South Pole South Pole with IceCube Amundsen-Scott South Pole Station AMANDA SPT, BICEP II

21 Amundsen-Scott South Pole Station Science and Facilities Amundsen-Scott South Pole Station runway runway IceCube IceCube Control Lab at the South Pole IceCube ARA South Pole South Pole South Pole with IceCube Amundsen-Scott South Pole Station AMANDA SPT, BICEP II

22 Antarctic Ice: Overburden at m (2200 m.w.e.) ~85 muons/m 2 /day at bottom of IceCube IceCube/DeepCore veto reduces rate by ~1-2 orders of magnitude. IceCube/ DeepCore veto DUSEL Homestake Preliminary Muon flux vs. depth in the ice, total and those untriggered by IceCube/DeepCore. (Darren Grant) 8

23 Petit et al, (1999) Nature 399 p. 429 Antarctic Ice: Radiopurity Measurements from ice cores at Vostok. Absorption and scattering lengths measured by AMANDA/ IceCube m at South Pole is ~100,000 years old Most of the impurities come from volcanic ash, < 0.1 ppm Radioactive contaminants in ice: U ~ ppt Th ~ ppt K ~ ppb J. Geophys. Res., 111, D13203 (2006) 9

24 Antarctic Ice: Temperature Temperature measured by each IceCube DOM, additional sensors on the cables At m, the ice is -20 C Temperature is stable throughout the year DOM Noise Rate vs. Temperature Kurt Woschnagg (IceCube) IceCube Collaboration, arxiv: , A&A 535, A109 (2011) 10

25 NaI(Tl) Detector Backgrounds Likely to be limited by intrinsic backgrounds in NaI crystals DAMA s crystal: 238 U: 5 ppt, 232 Th: 5 ppt, nat K: 20 ppb (NIMA 592 (2008) ) For reference, NaIAD crystal: 5-10x DAMA bgd in ROI (PLB 616 (2005) 17 24) Currently investigating several vendors simulated backgrounds from intrinsic contamination in DAMA crystals Simulated background spectrum from intrinsic contamination in DAMA crystals simulated activity in NaI crystals from radioactivity in ice Journal of Physics: Conference Series 203 (2010) TAUP2009 Kudryavtsev, Robinson, & Spooner TAUP2009 Kudryatsev et al. arxiv:

26 Seasonal Muon Rate Modulation The muon rate at the South Pole well measured by IceCube Temperature of the stratosphere in pressure layers, T P [K] IceCube muon rate [Hz] (black) & Teff [K] (red) Tilav et al, arxiv:astro-ph/

27 Seasonal Muon Rate Modulation The muon rate at the South Pole well measured by IceCube Temperature of the stratosphere in pressure layers, T P [K] Muon rate modulation with a single IceCube DOM IceCube muon rate [Hz] (black) & Teff [K] (red) IceCube Collaboration, arxiv: Tilav et al, arxiv:astro-ph/

28 Muon Rate at Gran Sasso vs. South Pole 5674% Expected DM peak (June 2) DAMA peak (May 26 ± 7 days) Borexino muon peak (Jul 6 ± 6 days) Selvi, Proc. 31 st ICRC. (2009) /00#12*.%!"#$%3#&"'()#$%(*%*,.%+#"*,%-#'.4% Tilav, Proc. 31 st ICRC. (2009) 5674% 13

29 DM-Ice-17: First Step Detectors: Two 8.5 kg NaI detectors from NAIAD (17 kg total) Goals: Assess the feasibility of deploying NaI(Tl) crystals in the Antarctic Ice for a dark matter detector Establish the radiopurity of the antarctic ice / hole ice Explore the capability of IceCube to veto muons 50m 1450m 2450m 2820m IceCube lab 2004: Project start 2010/2011: 7 Strings installed, Project completed with 86 strings IceCube In-Ice array 80 strings each with 60 DOMs AMANDA-II array (IceCube pre-cursor) DeepCore 6 strings each with 60 high quantum efficiency DOMs; optimized for low energies Installed Dec bedrock

30 DM-Ice-17 Detector 36 cm (14 ) DOM 59 2 IceCube mainboards + HV control boards 1.0 m 5 ETL 9390UKB PMTs from NAIAD NAIAD NaI Crystal (5 dia. x 5, 8.5 kg) quartz light guides 35 m extension cable DOM 60 PTFE light reflectors 7 m Stainless Steel Pressure Vessel DM-Ice

31 2 NaIAD Crystals from Boulby 2 crystals (17 kg) from the NaIAD experiment ( ) Intrinsic background 5 10 times the reported DAMA background before pulse-shape cut after Physics Letters B 616 (2005) Boulby Underground Laboratory (1100 m deep) Revived and tested two NaI crystals (Bicron) with two 5-inch ETL PMTs each. 16

32 Drilling into the Antarctic Ice IceCube Drill Camp IceCube Drill Camp IceCube Drill Hot water hose and deployment tower 17

33 DM-Ice-17 Construction & Deployment Detector assembly Flying to Antarctica Transport across the Ice Detector in the hole Deployment Team 18

34 DM-Ice Electronics in IceCube Counting Lab ICL beer can with string cables string cable penetrations into ICL domhubs patch panels event building 19

35 Get it there with MDS leaving Plane LC-130 Hercules Current Status & Future Outlook DM-Ice-17 deployed in December 2010 Currently taking data optimizing analysis, for energy, pulse shape cuts, coincidence between PMTs, etc. background studies with radio-assay & monte carlo simulation DM-Ice full-scale aims for rapid deployment Unique window of opportunity for an experiment at the South Pole IceCube drilling expertise Opportunity to run simultaneously with DAMA Optimization of detector size, geometry, and backgrounds R&D for low background crystals, calibration, pulse shape discrimination 20

36 DM-Ice Collaboration University of Wisconsin Madison Francis Halzen, Karsten Heeger, Albrecht Karle, Reina Maruyama, Carlos Pobes, Walter Pettus, Zachary Pierpoint, Antonia Hubbard, Bethany Reilly University of Sheffield Neil Spooner, Vitaly Kudryavtsev, Dan Walker, Matt Robinson, L. Thompson, Sam Telfer Boulby Underground Science Facility Sean Paling Fermilab Lauren Hsu Shanghai Jiao Tang University Xiangdong Ji, Changbo Fu University of Illinois at Urbana-Champaign Liang Yang NIST-Gaithersburg Pieter Mumm University of Stockholm Seon-Hee Seo SNOLAB Bruce Cleveland University of Alberta Darren Grant Penn State Doug Cowen University of Washington Seattle Sanshiro Enomoto, Jarek Kasper, Andreas Knecht DigiPen Charles Duba, Eric Mohrmann Special thanks to the IceCube team! 21

37 Drill Camp Packed for Future Use 22