Direct detection of dark matter An overview, not a review Paolo Gondolo University of Utah (On sabbatical at Seoul National University) Friday, June 8, 12
• Even if a new neutral particle is discovered at accelerators, one must still prove that it is the cold dark matter. Example: active neutrinos are neutral but are hot dark matter. • Indirect detection of dark matter is subject to poorly known astrophysical backgrounds, so it is hard to claim an unconditional discovery (exception may be gamma-ray line). • Direct detection seems the best way to prove the existence of particle dark matter. Friday, June 8, 12
The principle Rotation curve (Clemens 1985) 3 kpc Sun 8.3 kpc Our galaxy is inside a halo of dark matter particles Image by R. Powell using DSS data Friday, June 8, 12
The principle Dark matter particles that arrive on Earth scatter off nuclei in a detector CDMS EDELWEISS DAMA CRESST KIMS DRIFT crystal XENON COUPP (or gas CoGeNT Dark or liquid) TARP DMTPC matter TEXONO ..... CRESST particle Low-background underground detector Friday, June 8, 12
Background discrimination Finding the dark matter particles is a fight against background Directional discrimination From Sanglard 2005 Friday, June 8, 12
DM Direct Search Progress Over Time (2009) ~1 event kg -1 day -1 ZEPLIN III.1 CDMS Soudan 2008 (Gross Masses kg) ZEPLIN III.2 WARP 140kg XENON 100kg SuperCDMS XMASS 800kg 25 kg LUX 350kg SuperCDMS XENON 1000kg 125 kg LUX-ZEP 3000kg ~1 event 1 tonne -1 yr -1 σ =10 -48 LZ 20t 13 Dark Matter, Sept 2007 Rick Gaitskell, Brown University, DOE Gaitskell 2009 Friday, June 8, 12
Coming up...... • XMASS (800 kg LXe, Kamioka, 2011-) • SuperCDMS (25kg Ge, Soudan, 2012-) • LUX (350 kg LXe, Homestake, 2012-) • DarkSide (50 kg LAr, Gran Sasso, 2012-) • COUPP (60 kg CF 3 I, SNOLab, 2012-) • XENON-1T (1 ton LXe, Gran Sasso, 2014-) • DM-ICE, EURECA, DARWIN, and many many others Friday, June 8, 12
The annual modulation Drukier, Freese, Spergel 1986 Annual modulation in WIMP flux and detection rate S = S 0 + S m cos[ ω ( t − t 0 )] The WIMP bulk velocity w.r.t. Earth modulates from ~232+15 km/s to ~232-15 km/s with a period of one year Friday, June 8, 12
The DAMA modulation DAMA finds a yearly modulation as Bernabei et al 1997-2012 expected for dark matter particles 2-6 keV Residuals (cpd/kg/keV) DAMA/LIBRA � 250 kg (0.87 ton × yr) 8.2 σ detection Time (day) S m (cpd/kg/keV) 0.05 0.025 0 -0.025 S = S 0 + S m cos[ ω ( t − t 0 )] -0.05 = S 0 + S m cos[ ω ( t − t 0 )] 0 2 4 6 8 10 12 14 16 18 20 Energy (keV) Friday, June 8, 12
The CoGeNT modulation The CoGeNT “irreducible excess’’ (*) modulates with a period of one year and a phase compatible with DAMA’s annual modulation. Aalseth et al 1106.0650 (*) Partly due to extra surface events Friday, June 8, 12
The CRESST unexplained excess 67 observed events cannot all be explained by background at 4 σ total 8 WIMP signal Unexplained γ bck accepted events / keV Pb recoil bck 6 α bck neutron bck 4 2 0 f 10 15 20 25 30 35 40 Energy [keV] Adapted from Anglehor et al 2011 Friday, June 8, 12
The CRESST unexplained excess 67 observed events cannot all be explained by background at 4 σ -3 10 CRESST 1 σ CoGeNT DAMA CRESST 2 σ CRESST 2009 DAMA WIMP-nucleon cross section [pb] -4 EDELWEISS-II 10 M2 CDMS-II CRESST XENON100 DAMA chan. -5 10 DAMA CoGeNT M1 -6 10 ! s P M EDELWEISS-II I W -7 t 10 h g i L CDMS -8 10 XENON100 -9 10 10 100 1000 WIMP mass [GeV] model-dependent Adapted from Anglehor et al 2011 Friday, June 8, 12
Limits from XENON-100, KIMS, CDMS, ..... Upper limit on WIMP-nucleon cross section from XENON-100 (model dependent) -39 -39 10 10 DAMA/Na -40 -40 10 10 ] ] 2 2 WIMP-Nucleon Cross Section [cm WIMP-Nucleon Cross Section [cm CoGeNT DAMA/I -41 -41 10 10 CDMS -42 -42 10 10 EDELWEISS -43 -43 10 10 XENON100 (2010) -44 -44 10 10 XENON100 (2011) Buchmueller et al. -45 -45 10 10 6 7 8 910 6 7 8 910 20 20 30 30 40 50 40 50 200 200 300 400 300 400 100 100 1000 1000 2 2 WIMP Mass [GeV/c WIMP Mass [GeV/c ] ] 3 events observed Aprile et al (XENON-100) 1104.2549 1.8±0.6 expected background Friday, June 8, 12
Limits from XENON-100, KIMS, CDMS, ..... KIMS: CsI scintillation detector (similar to DAMA) • Excludes inelastic dark matter • Excludes 60 GeV/c 2 DAMA region Without using detectors with large surface α background Kim at TAUP 2011 Friday, June 8, 12
Rate [kg day keVnr] −1 � 0.5 −0.5 � Days Since Jan. 1st −1 Limits from XENON-100, KIMS, CDMS, ..... � CDMS does not observe an Rate [kg day keVnr] −1 � 0.5 annual modulation and constrains its amplitude 0 Ahmed et al 1203.1309 −0.5 � 0 200 400 600 Days Since Jan. 1st CoGeNT CDMS −1 Recoil Energy [CoGeNT keVee] Modulated Rate [kg day keVnr] −1 0 0.50 1.21 1.85 2.51 3.20 � /2 (~Apr.1) Rate [kg day keVnr] −1 0.5 0.6 0.4 � 0.2 −0.5 0 � (Jan.1) (~Jul.1) 0 Days Since Jan. 1st 5 7 ] −1 1 . −0.2 0 y a d 0 2.27 5 7.3 9.6 11.9 g k r Recoil Energy [keVnr] n V e k [ 5 3 . model-independent 0 3 � /2 (~Oct.1) Friday, June 8, 12 −1 −1 −0.2 −0.2
CoGeNT & DAMA vs. XENON, CDMS, et al 10 − 38 WIMP − nucleon cross section (cm 2 ) CDMS shallow-site 10 − 39 DAMA Not compatible 10 − 40 CoGeNT /DAMA DAMA 10 − 41 2 4 6 8 10 100 WIMP mass (GeV/c 2 ) Akerib et al (CDMS) PRD82, 122004, 2010 Friday, June 8, 12
CoGeNT & DAMA vs. XENON, CDMS, et al 10 − 38 -39 -39 10 10 WIMP − nucleon cross section (cm 2 ) DAMA/Na CDMS shallow-site -40 -40 10 10 ] ] 2 2 WIMP-Nucleon Cross Section [cm WIMP-Nucleon Cross Section [cm CoGeNT DAMA/I 10 − 39 -41 -41 10 10 DAMA Not compatible CDMS Not compatible -42 -42 10 10 EDELWEISS 10 − 40 CoGeNT /DAMA -43 -43 10 10 DAMA XENON100 (2010) 10 − 41 -44 -44 10 10 XENON100 (2011) Buchmueller et al. 2 4 6 8 10 100 -45 -45 10 10 6 7 8 910 6 7 8 910 20 20 30 30 40 50 40 50 200 200 300 400 300 400 100 100 1000 1000 WIMP mass (GeV/c 2 ) 2 2 WIMP Mass [GeV/c WIMP Mass [GeV/c ] ] Aprile et al (XENON-100) 1104.2549 Friday, June 8, 12
CoGeNT & DAMA vs. XENON, CDMS, et al 10 − 38 -39 -39 10 10 10 � 2 WIMP − nucleon cross section (cm 2 ) DAMA/Na DAMA modulation CDMS shallow-site -40 -40 10 10 � 5 Σ � 3 Σ � 90 � � 10 � 3 ] ] 2 2 WIMP-Nucleon Cross Section [cm WIMP-Nucleon Cross Section [cm CoGeNT DAMA/I DAMA 10 − 39 total events 10 � 4 -41 -41 10 10 DAMA Not compatible XENON10 CDMS Σ Χ p � pb � Not compatible 10 � 5 XENON100 -42 -42 10 10 EDELWEISS 10 − 40 CoGeNT CoGeNT � 7 � 12 GeV � 10 � 6 /DAMA -43 -43 10 10 CDMS DAMA 10 � 7 XENON100 (2010) spin � independent 10 − 41 Barely compatible -44 -44 10 � eff constant below 3.9 keVnr 10 XENON100 (2011) Buchmueller et al. 10 � 8 10 0 10 1 10 2 2 4 6 8 10 100 -45 -45 10 10 6 7 8 910 6 7 8 910 20 20 M WIMP � GeV � 30 30 40 50 40 50 200 200 300 400 300 400 100 100 1000 1000 WIMP mass (GeV/c 2 ) 2 2 WIMP Mass [GeV/c WIMP Mass [GeV/c ] ] Savage, Gelmini, Gondolo, Freese 2010 Aprile et al (XENON-100) 1104.2549 Friday, June 8, 12
CoGeNT & DAMA vs. XENON, CDMS, et al 10 − 38 -39 -39 WIMP � nucleon cross section Σ SI � cm 2 � 10 � 39 10 10 10 � 2 C Lim its: 90 � D DAMA WIMP − nucleon cross section (cm 2 ) DAMA/Na M Countours: 90 � , 3 Σ DAMA modulation S CDMS shallow-site � q � 10 � � -40 -40 l 10 10 � 5 Σ � 3 Σ � 90 � � o 10 � 3 w ] ] 2 2 WIMP-Nucleon Cross Section [cm WIMP-Nucleon Cross Section [cm � CoGeNT DAMA/I DAMA t 10 − 39 h total events r 10 � 4 -41 -41 10 10 10 � 40 DAMA CoGeNT � no contam. � Not compatible XENON10 CDMS � Σ Χ p � pb � Not compatible 10 � 5 CoGeNT � small contam. � XENON100 -42 -42 10 10 EDELWEISS 10 − 40 CoGeNT CoGeNT CoGeNT � large contam. � � 7 � 12 GeV � 10 � 6 /DAMA -43 -43 10 10 10 � 41 CDMS DAMA XENON � 100 10 � 7 XENON100 (2010) spin � independent 10 − 41 Barely compatible -44 -44 � eff constant below 3.9 keVnr 10 10 XENON100 (2011) v 0 � 220 km � s Buchmueller et al. 10 � 8 10 0 10 1 10 2 v esc � 550 km � s Not compatible 2 4 6 8 10 100 -45 -45 10 10 10 � 42 6 7 8 910 6 7 8 910 20 20 M WIMP � GeV � 30 30 40 50 40 50 200 200 300 400 300 400 100 100 1000 1000 WIMP mass (GeV/c 2 ) 2 2 WIMP Mass [GeV/c WIMP Mass [GeV/c ] ] 6 8 10 20 WIMP mass m Χ � GeV � Savage, Gelmini, Gondolo, Freese 2010 Aprile et al (XENON-100) 1104.2549 Kopp, Schwetz, Zupan 2011 Friday, June 8, 12
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