Indirect Dark Matter Search with Antideuterons: Progress and Future Prospects for General Antiparticle Spectrometer (GAPS) T Aramaki, C J Hailey, J Jou, J E Koglin, H T Yu Columbia Astrophysics LaboratoryW W Craig, L Fabris, N Madden, K P Ziock Lawrence Livermore National LaboratoryF Gahbauer University of Latvia/Columbia UniversityK Mori CITA/Toronto

Thanks to J Collins and LLNL electronics shop, T Decker, R Hill, G Tajiri, M Ieiri and the KEK staff Support in part by a NASA SR&T grant, NAG5-5393

How Does Cold Dark Matter Generate Antideuterons? Pair annihilating WIMPS produce: g, n, e+

Donato et al. (2000) suggest antideuteron signal_p

Low energy, neutralino-neutralino producedantideuterons are near background freePrimary component: neutralino annihilation _ X+X D

Secondary component: spallation _ p+H p+H+D+D _ p+He p+He+D+D

Clean signature @ low E, but see Baret et al. 2003However, sensitivity demand is daunting Antideuteron flux at the earth (with propagation and solar modulation)PrimarySecondary

GAPS is based on radiative emission ofantiparticles captured into exotic atomsTOF_DTargetSegmented DetectorLadder DeexcitationsDn=1, Dl=1NuclearAnnihilation19 keV75 keV35 keVp*p*p*Anti-protonic atoms (in addition to Muonic, Pionic, Kaonic atoms) extensively studied and atomic transitions well understood.Auger e-Refilling e-

Comparison of Direct & Indirect Antideuteron Detection Sensitivities for SUSY DMThere are ~20 current or planned direct detection experimentsIndirect Antideuteron search offers a complementary methodCDMS (Soudan) 2005 Si (7 keV threshold) CDMS (Soudan) 2004 + 2005 Ge (7 keV threshold) CDMS Soudan 2004+2005 Ge/Si SD-neutron/protonCDMSII (Projected) Development ZBG SuperCDMS (Projected) Phase C CDMSII (Soudan) projected CUORICINO projected exclusion limit COSME 2001 Exclusion Limit, 72.7 kg-days CRESST-I projection limit, Al2O3 CRESST-II projected limit, CaWO4 CRESST I SD-neutron/protonCRESST II SD-neutron/protonDAMA 2000 58k kg-days NaIDAMA 2003 NaI SD-neutron/protonDAMA Xe129 DMRC projection for 100kg CsI, 1cpd ELEGANT V NaI SI/SD limit, OTO COSMO Observatory Edelweiss I final limit, 62 kg-days Ge 2000+2002+2003 limit Edelweiss SD-neutron/protonEdelweiss Ge, projected GEDEON projection Genius Test Facility projected limit, 2001, energy threshold 2 keV Genino projected exclusion limit, DM2000 Heidelberg - Genius, projected IGEX projected exclusion limit (for 1kgyr) IGEX 2002 Nov limit NAIAD 2005 final result SI/SDPICASSO SD-neutron/proton (2005)SIMPLE SD-neutron/protonZEPLIN I First Limit (2005) NAIAD spin indep. projected limit, 12 p.e./keV with 100 kg-yrs exposure XENON100 (100 kg) projected sensitivity XENON10 (10 kg) projected sensitivity XENON1T (1 tonne) projected sensitivity ZEPLIN I SD-neutron/proton(preliminary) ZEPLIN 2 projection ZEPLIN 4/MAX projected (2004) SuperK indirect SD-proton Baer & Profumo 2005

Detector approach was dictated by trade between performance and shoe string budget16 NaI(Tl) detector modules covering 40 cm long x 12 cm diameter target cellEach modular 4x2 arrays of 25mm diameter x of 5 mm thick crystals (128 total)Solid angle coverage ~ 0.32004 KEK Experiment

KEK Accelerator Tests to Demonstrate Fast-timing, Multi-X-ray Spectroscopy ApproachTOF [ns]E [keV]TOF & Shower Beam CountersNaI Detector [keV]Charged Veto [MeV]-0.3-0.22.32.73.33.950921980.20.40.2p*p*p*TOF Trigger CountersDegraderShower CountersExotic AtomAtomic TransitionsNuclear Annihilation

2004 KEK GAPS ResultsWe clearly get X-rays when we dump Antiprotons into our gas target50100150200250300NaI Energy Deposit [keV]No TargetHailey et al. 2005 (accepted by JCAP)

Solid and Liquid Targets Tested in 2005AlTargets chosen based on known, high Kaonic yields Goal to measure Antiprotonic atom yields

CBr4 KEK 2005Cut: 2 X-ray & 4 total signalsMulti-X-ray Spectrum4 X-ray Transition EventHailey et al. 2005 (accepted by JCAP)

Sulfur KEK 2005Cut: 2 X-ray & 4 total signalsMulti-X-ray Spectrum2 X-ray + 3 p* EventHailey et al. 2005 (accepted by JCAP)

Preliminary results from KEK experiments Solid targets have been successfully utilized: simplification over initial gas concept is enormous Gaseous Antiparticle Spectrometer General Antiparticle Spectrometer Pion stars provide substantial additional antiparticle identification Preliminary results on X-ray yields per capture are consistent with those used in original sensitivity calculationsNon-antiparticle background is cleanly identified and rejected Conclusion: GAPS is probably more promising than originally anticipated

Goal is to conduct balloon-based GAPS antideuteron search by 2009-2010Investigate flight detectors (e.g., CZT, LaCl, NaI), readout geometries (PMT, APD, fiber-coupled scintillator bars) and low cost electronics. 2006-2007Detailed design and simulation of flight geometry, extending on original work. 2006-2007Design and construction of gondola and first flight module. 2007-2008Flight test of prototype GAPS possibly from Sanriku in Iwate, Japan. 2008 (T Yoshida & H Fuke have recently joined GAPS collaboration)LDB flight from Antarctica or ULDB flight from Australia (if available). 2009-2010

A compilation of the various sources of uncertainty in the primary antideuteron flux computation,expressed as the ratio of the antideuteron flux in the models under consideration over that of a referencesetup, defined in the text. Panel (a) shows the nuclear reaction uncertainty parameterized by the variation ofthe coalescence momentum p0 within the range 30 < p0/MeV/c < 140. Panel (b) highlights the uncertaintydue to the diffusion of the antideuterons in the galactic halo, induced by the diffusion halo thickness L, whichwas varied within the range 1 < L/kpc < 15 and within the (more realistic) range 3 < L/kpc < 7 [22] (blueshaded column), by the galactic wind velocity vW, varied in the range 0 < vW/km/s < 20, and by the diffusioncoefficient K0, varied in the range 15 < K0/(1027cm2/s) < 35. Panel (c) shows the variation of the flux withthe solar activity, due to modulation of the antideuteron flux in the heliosphere. The modulation parameter was varied between 300 and 1000 MV. Finally, panel (d) sketches the uncertainty originating from the structureof the DM halo, showing the resulting flux variation for two well-known halo profiles, the NFW profile [82] andthe Burkert profile [83], and the enhancement factor due to DM clumps, as computed in Ref. [84]. The lightshaded area above the = 5 line reminds the possibility of a larger boost factor from halo clumpiness [85].

(but see Barrau 2004)C Target X-rays for DbarFigure 5: (Left panel): The correlation between the expected sensitivity of antideuteron searches and of directdetection experiments for supersymmetric models giving a thermal neutralino relic abundance in the WMAPrange. On the y axis we indicate the ratio of the neutralino-proton spin-independent scattering cross sectionover the projected maximal sensitivity of the CDMS-II experiment, at the WIMP mass corresponding to theneutralino mass for the model under consideration. On the x axis we indicate the number of expected primaryantideuterons detected at the ULDB GAPS mission (ratio of the average flux over the experimental sensitivity).(Right panel): the same as in the left panel, but correlating the sensitivity of antideuteron searches at GAPSon a ULDB mission with that IceCube for the neutralino-annihilation induced flux of muons from the center ofthe Sun.

~0.5 M beam Pbars~1500 exotic atoms formed~100 X-ray transitions in each line expectedExpect ~100 accidental X-rays from ambient background the rest are beam related