GAPS antiproton and antideuteron measurement for indirect dark matter search

Transcription

1 GAPS antiproton and antideuteron measurement for indirect dark matter search Hideyuki Fuke (JAXA/ISAS) for the GAPS collaboration Ref. Poster #P-07 7 th /Mar./2016 Kanazawa

2 GAPS: General Anti-Particle Spectrometer 1 Science Goal: Indirect Search for Dark Matter 2 Main Probe: Cosmic-ray Anti-deuteron 3 Original Detection Method using Exotic Atom Physics 4 Observation by Long-Duration Balloon Flight over Antarctica 5 Success of Engineering Verification by pgaps

3 Numerous Theories and Numerous Experiments Theoretical DM candidates Axinos Bino Brane world DM CHAMPS Cryptons D-matter Gravitinos Kaluza-Klein Higgsino Light scalars Minimal DM Mirror particles Neutralinos New symmetry little heavy neutrino Higgs Q-balls Photino Self-interacting DM Simpzillas SM neutrinos Sneutrinos Sterile neutrinos SWIMPS little Higgs Wimpzillas Wino Experiments investigating DM AMS-2 AMANDA ASTRO-H ATIC BESS BETS CALET CDMSII CDMSlite CUORICINO COSME CoGeNT CRESST-I II DAMA/LIBRA DAMA/NaI DarkSide ELEGANT V EDELWEISS Fermi-LAT GAPS GEDEON Genius Genino HESS IceCube IGEX LHC LUX NewAge PAMELA GAPS is unique!! PICASSO SIMPLE SNOLAB NAIAD XENON XMASS ZEPLIN SuperCDMS SuperK Tevatron VERITAS Investigation from various perspectives is important to solve the DM puzzle.

4 Main Probe: Cosmic-ray Anti-deuteron GAPS searches for antiparticles, especially antideuterons ( d s), in the cosmic radiation. d can be produced by d p n self annihilation or decay of various WIMP DM candidates. d produced in the Galactic halo can reach us. Not only the Galactic center but the whole halo. Cosmic-ray d is undiscovered and unexplored.

5 Anti-deuteron is Background Free Energy spectra of d expected from various DM candidates are soft with a peak at low energies below ~1 GeV. Energy spectrum of secondary (collisional) d must be suppressed in the low-energy region due to kinematics. p + H p + H + p + n + p + n Background Free!! Different from other indirect probes such as γ, p, e +, ν, etc. Detection of even a single d event provides significant constraints on DM models. ( smoking gun ) Expected flux itself is very low. F. Donato et al., Phys. Rev. D 78, (2008). H. Baer, S. Profumo, JCAP 0512:008 (2005). L. Dal, A. Raklev, Phys. Rev. D, 89, (2014). Primary D O(2) Background D

6 Direct Search GAPS surveys wide parameter space complementary to other experiments. IceCube Direct Search GAPS GAPS Baer & Profumo 2005, MSSM; is excluded by antiproton flux.

7 GAPS covers hot-topic light DM models Light DM model (mass GeV) Detection of light DM was claimed by direct searches of CDMS-II-Si, DAMA, CoGeNT. But rejected by other direct searches of XENON100, LUX, SuperCDMS. It s around the threshold of detectable mass range of direct searches. GAPS Excess of halo γ-ray claimed by Fermi-LAT can be also interpreted by ~30 GeV DM. GAPS covers these light DM models. Red: WMAP-preferred density range Blue: thermally generated neutralino subdominant Gray: ruled out by current anti-proton data Non-universal gaugino Minimal SUSY high-mass neutralino

8 Other examples of DM covered by GAPS C. Brauninger et al., Phys. Lett. B 678, 20 (2009) TeV mass Heavy DM in the b-bbar channel. Y. Cui et al., J. High Energy Phys. 1011, 017 (2010). Less than a few hundred GeV mass neutralino annihilation in the gluon-gluon channel. M. Grefe, J. Phys. Conf. Ser (2012). L. Dal et al., arxiv: (2014). Less than 300 GeV mass gravitino produced in R-parity violating decays. (not excluded by any other experiments). Antiproton ( p ) measurement w/ high statistics in ultra low energy is sensitive to light neutralino, gravitino, LZP, etc.

9 How to detect by GAPS Conventional method of magnetic mass spectrometer is not optimal for a deep survey, because very large magnet with thin detector material and much cryogenic refrigerant are needed. GAPS introduces an original method which is relatively easier both to enlarge the instrument and to elongate the flight time. Calorimetric capture of cosmic-ray anti-particle. Deexcitation sequence of exotic atom. Trajectory detection of secondary productions (X-rays and charged particles) which characterize the incoming anti-particle species. d Nucleus Anti-deuteron Exotic Atom

10 How to detect d by GAPS TOF π + Si(Li) π - p π - 44keV 30keV 67keV π - 1. Once d is slowed down and stopped in the target, 2. an excited exotic atom is formed, 3. which deexcites with emitting X-rays, 4. and annihilates with producing a pion/proton shower. By KEK antiproton accelerator beam tests in 04~ 05, this detection principle was verified and high X-ray yield was shown. d K. Mori et al., Astrophys. J. 566 (2002) 604. C.J. Hailey et al., Nucl. Instr. Meth. B 214 (2004) 122. C.J. Hailey et al., JCAP (2006) 007. π - p Si π + p d Exotic Atom n=1 n=2 Refilling e - n=6 n=7 π Atomic Transitions Auger e - n=8 π p n=9 E n=n K ~15 γ γ γ Ladder Deexcitations Δn=1, Δl=1 n o,l o 2 * ( zz) M R H 2 nf ni γ = 2 1 Nuclear Annihilation 1

11 Si(Li) semiconductor detector 1350 of φ4 wafers mounted on 10 of 2m 2m layers. ΔE ~ 3keV. degrader, depth sensing, target, X-ray measurement (20~70keV), π/p tracker. Plastic scintillation counter Thin paddle surrounding the Si(Li) stack. Δt ~ 0.5nsec. trigger, time-of-flight, de/dx, arrival direction, π/p detection, veto. d can be distinguished from p by observing 1~2 X-rays + 5~6 pions/protons GAPS detector design Plastic Scintillation Counters Si(Li) detectors Radiator

12 GAPS detector design Si(Li) semiconductor detector 1350 of φ4 wafers mounted on 10 of 2m 2m layers. ΔE ~ 3keV. degrader, depth sensing, target, X-ray measurement (20~70keV), π/p tracker. Plastic scintillation counter Thin paddle surrounding the Si(Li) stack. Δt ~ 0.5nsec. trigger, time-of-flight, de/dx, arrival direction, π/p detection, veto. d can be distinguished from p by observing 1~2 X-rays + 5~6 pions/protons TOF Si(Li) p

13 Highly sensitive search by Antarctic balloon flight Long-duration balloon flight in the polar region is very suitable for GAPS; Observation of low-energy charged particles with less geomagnetic suppression. Direct detection of cosmic-rays at an adequate atmosphere depth. Cost-efficient than deep space satellite. Conv. GAPS plans to carry out multiple science flights by NASA Antarctic long-duration balloon around Solar minimum period is suitable with less solar modulation suppression. GAPS will exceed the BESS limit by 2 orders of magnitude. GAPS will reach a sensitivity comparable to 5 yrs AMS-02 on the ISS. Aramaki et al., Astropart. Phys. 74 (2016) 6. Aramaki et al., Astropart. Phys. 59 (2014) 12.

14 Comparison to AMS-02 Conv. AMS is a magnetic spectrometer on the ISS. AMS changed its design in 2010 before the launch (supercon. permanent magnet, etc). The AMS d sensitivity was estimated before (PhD thesis of F. Giovacchini (2007)) The detector material thickness limits the lowest detectable energy of AMS where the S/N ratio is maximum. The ISS orbit is not suitable for the sub-gev cosmic-ray observation. Hard effort must be needed for the correction of geomagnetic field effect. GAPS and AMS are complementary; GAPS surveys an energy region neighbor to AMS with quite different detection technique with 3 orders of magnitude less money.

15 Time Line Study of Detection Principle KEK Beamtests NASA grant for pgaps started ISAS/WG Technical Validation Columbia-ISAS LOA pgaps flight in Japan Critical Design Now NASA AO Antarctic Science Flights Collaboration GAPS is a US-Japan joint collaboration consisting of ~ 40 members (scientists, engineers, and students). Prof. Chuck Hailey (Columbia Univ.) is PI of US team. Applying for NASA & JAXA grants. LDB (or ULDB) flight from Mc Murdo

16 pgaps : a prototype GAPS flight pgaps is an engineering flight to verify and demonstrate the basic performance of each GAPS subsystem in actual balloon-flight conditions. pgaps was launched from JAXA s balloon launch site at Taiki, Japan. Goals of pgaps are: to operate Si(Li) and TOF systems at float altitude and ambient pressure, to verify the thermal design of Si(Li) cooling, and to measure the incoherent background level. No antiprotons nor antideuterons detection, because of: high rigidity cutoff (~8 GV), short flight time (~3 floating hours), and small detector acceptance (~0.054 m 2 sr). TOF counters (3 X-Y layers) Si(Li) detectors with cooling pipes DAQ electronics, Flight computer, Data storage 1.4 m W, 1.6 m L, 2.2 m H, 450 kg, 530 W

17 pgaps Flight on 3 rd /June/2012 was just as expected. Launch Splash down Boomerang balloon operation ~3 hours at floating altitude

18 Full success of pgaps More than 1 million events were recorded during the flight. All the success criteria were met: Stable, low-noise operation of Si(Li) and TOF. Si(Li) cooling approach functioned as expected. Incoherent background was measured in flight-like configuration. Si(Li) Fuke et al., Adv. Spa. Res. 53 (2014) Mognet et al., NIM A 735 (2014) 24. Doetinchem et al. Astropart. Phys. 54 (2014) 93. ΔE ~ 4 5 kev TOF Δt~ sec Trigger rate was consistent with the radiation estimation.

19 Summary GAPS is an indirect search experiment of CMD through searching for undiscovered cosmic-ray anti-deuterons. GAPS is unique both in its probe ( d ) and its detection technique, and will provide a golden piece complementary with other experiments to solve the DM puzzle. A prototype GAPS balloon flight was successfully carried out. All success criteria was met, and all the key technologies were demonstrated. Now it s time to realize the Antarctic GAPS flight!! Ref. Poster #P-07 GAPS is supported in Japan by MEXT Grants KAKENHI and JAXA/ISAS Grants and in the US by NASA/APRA Grants and the UCLA funds.