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Multi Purpose Detectors/Targets for L ow E nergy P article and A stro P hysics ( LEPAP ):

Multi Purpose Detectors/Targets for L ow E nergy P article and A stro P hysics ( LEPAP ):. Stefan Sch ö nert MPIK Heidelberg Journ ées Neutrinos Paris, 27/28. 11. 2003. Status & perspectives for LEPAP. Dark Matter: direct detection of non-baryonic DM.  - properties: Sun :

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Multi Purpose Detectors/Targets for L ow E nergy P article and A stro P hysics ( LEPAP ):

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  1. Multi Purpose Detectors/Targets forLow Energy Particle and AstroPhysics (LEPAP): Stefan Schönert MPIK Heidelberg Journées Neutrinos Paris, 27/28. 11. 2003

  2. Status & perspectives for LEPAP • Dark Matter: • direct detection of non-baryonic DM • -properties: • Sun: •  full picture on osc. •  12 • Reactor: •  13(compl. to accelerator) •  msol² and 12 • DBD: •  Ł, Majorana type •  hierarchy, abs. mass scale • Kinematics: •  absolute mass scale • ’s as probe for astro- and geophysics: • Sun: precision meas. pp, Be7, pep, CNO  stellar evolution • SN: dynamics of core collapse, relic SN • Earth: energetics of the earth Near future: several groups (in Europe) will define future research projects  coherence & complementarity

  3. Eier legende Wollmilchsau (oviparous wool-milk-pig) Is there an experimental method which can do everything ? Isotopes/techniques for future exps.: • He (SUN) (HERON) • Ar (LB, p-decay, SUN,DM) (ICARUS,WARP) • Ne (SUN, SN, DM) (CLEAN) • Xe (DM, DBD, SUN) (XMASS, XENON, EXO,TPC) • Ge (DBD, DM) (GeLN) • Mo (DBD, SUN, SN) (MOON) • Nd(DBD) • In (SUN) (LENS) • Organic LS (SUN, REACTOR, EARTH, SN, p-decay) (KamLAND, BOREXINO, LENA)

  4. Specific requirements (beyond low-background) • DBD: • energy resolution • single site vs. extended evts. • tracking • daughter tagging • DM: • low threshold • annual modulation • event-by-event discr. (recoil vs. ionization) • Solar-: • Bq/m3 impurities • tag • target mass > 10 t • SN dynamics: • target mass 30kt • tag Requirements sometimes orthogonal!

  5. “A Multi-Purpose Matrix” obviously non-diagonal Xe Ge Mo LS Ar DMxx - - ? DBDxxx - - Solarx ? xx x SN - - xxx Geo - - - x- p-dec. - - - xx LBL- - - - x • Matrix obviously incomplete • No weight factor for competiveness • Not included the most successful multi-purpose detector SK

  6. Ionisation Electron/nuclear recoil Xe+ Excitation +Xe Xe2+ +e- (recomb- ination) Smith, IDM2002 Xe* Xe** + Xe +Xe Xe2* 175nm 175nm Triplet Singlet 3ns 27ns 2Xe 2Xe ElectricField Xe EL UV light LXe e- Xe+ SC UV light Xe for DM • Discrimination ionizing vs. recoil events by • Pulse shape of scintillation light • Electroluminescence / Scintillation

  7. Xe for DM Single phase detectors “pragmatic approach” • Zeplin 1: • Discrimination recoil/ionization via pulse shape • XMASS (100 kg) Reduction of background, self shielding

  8. Xe for DM – XMASS 100kg Low BG PMT 238U 1.8x10-2Bq 232Th 6.9x10-3Bq 40K 1.4x10-1Bq 60Co 5.5x10-3Bq

  9. Xe for DM - XMASS • “pragmatic approach”: • Single phase detector • Minimizing external background by self shielding • Minimizing internal background by purification • Pulse shape discrimination? 800kg detector 80cm dia.

  10. Xe for DM – XMASS 800 kg external g ray (60cm, 346kg) external g ray (40cm, 100kg ) • Dominant contribution is from PMT • Assuming further 1/10 reduction of PMTs BG /kg/day/keV 2n2b, 8x1021 yr 7Be pp Dark matter (10-8 pb, 50GeV, 100 GeV)

  11. Xe for DM – XMASS 800 kg sensitivity Spin independent Seasonal variation spectrum

  12. Xe for DM Two phase detectors: “sophisticated approach” Discrimination recoil vs. ionization: SC & EL • Zeplin 1+i • XMASS (2-Phase) • XENON Gas ~1μs anode grid Drift Time e- E Liquid ~40ns g-ray cathode

  13. 10 ton detector External g ray BG only (c.f. dru=/kg/day/keV) Total vol. 10cm wall cut 20cm 30cm (FV 2.2t) 30cm + ½ PMT cut Eff. @300keV~50% Xe for DBD - XMASS XMASS 10t too small for DBD: self shielding at Qenergies insufficient

  14. Symbolically… Xe for DBD - XMASS Moriyama, NOON03

  15. Xe for DBD - XMASS Put ＰＭＴ away Water shield Xe vessel + wavelength shifter Double focus mirror Water shield Scintillation light Xe vessel + wavelength shifter PMTｓ

  16. Xe for DBD – EXO“very sophisticated approach” EXO: Scintillation & Charge & Ba-tagging

  17. Xe for Solar- Detector with ~20t (10t fid. Vol) 2nbbdecay of 136Xe t1/2 theory= 8 x 1021 y sin22q = 0.77  0.03(stat.+SSM) ~1/100 reduction needed

  18. Ge for DBD • Q(76Ge) = 2.039 MeV • 5 detectors operating @ LNGS • 10.96 kg active mass (86% enriched) • 125.5 mol of 76Ge t1/20n> 1.9  1025 y mee < 0.35 eV (90% c.l.) Heidelber-Moscow Collaboration: H.V. Klapdor-Kleingrothaus, A. Dietz, L. Baudis, G. Heusser, I.V. Krivosheina, S. Kolb, B. Majorovits, H. Paes, H. Strecker, V. Alexeev, A. Balysh, A.Bakalyarov, S.T. Belyaev, V.I. Lebedev, and S. Zhukov Eur. Phys. J. A 12 (2001) 147

  19. 76Ge: sensitivity, exposure and background 0.0001 0.001 0.01 0.06 / (kg year keV) HEIDELBERG-MOSCOW Collaboration, Eur. Phys. J. A 12 (2001) 147: M·T = 35.5 kg y, b = 6 ·10-2 (kg y keV), DE ~ 4.2 keV Sensitivity (with bgd): mee (b DE / M T)1/4

  20. Ge for DBD – “pragmatic approach” Ge in liquid nitrogen/argon Background in HD-M/IGEX dominated by external impurities  Strategy to improve sensitivity (“pragmatic approach”): reduction of background: 2 ·10-1 / kg y keV (@2040 keV)  10-4/kg y keV (operation of “naked” Gediodes in liquid nitrogen/argon Increase of mass step by step  100 kg • New Initiative at • MPIK Heidelberg: (H. Heusser, W. Hofmann, K.T. Knoepfle, S. Schönert, B. Schwingenheuer, H. Simgen) • Univ. Tuebingen • INR/ITEP • Open for new partners : France ??? LOI to LNGS in spring

  21. New concept under study “somewhat sofisticated approach”: Ge in liquid Ar – new ideas • Replace LN (LN=0.8 g/cm³, 77 K) by LAr (LN=1.4 g/cm³, 87 K)  LAr/ LN (2.615 MeV) = 0.62 • Scintillation yield: 40,000 photons / MeV  Active shielding medium! (4 x organic liquid scintillator) Emission in XUV (~130 nm) • Wavelength shifting required : Organic WLS and/or Xe addition • Essential for cosmogenic activities: Co-60, Ge-68, … • What’s about Ar-39, Ar-42 ?

  22. LN2 shield against external background radiation LNGS: ~ 107 /m²/d (2.6 MeV ) ~6 m 10-4 (kg keV y) -1 LN2

  23. Space @ LNGS ~14 m 14.80 m

  24. How small could a tank be? • Lead layer submersed in LAr • 232Th activity of lead  tank Ø • Preliminary results 30Bq/kg 

  25. Bgd. in LAr: example 42Ar 42Ar / natAr = 3·10-21 (30 Bq/kg) [Barabash et al., LAr-TPC @ LNGS]

  26. Wavelength shifter Reflector (VM2000) 42Ar: no vs. active suppression , 1,2 No issue for DBD even without active suppression!

  27. Active suppression of internal bgd: example 60Co • Cosmogenic activities: • Production after completion of crystal growth • Exposure to cosmic rays above ground for 10 days: 0.18 Bq/kg [GENIUS]

  28. , Wavelength shifter Reflector (VM2000) Reduction factor ~100 60Co: no vs. active suppression

  29. External bgd: example 2.615 MeV gamma 232Th (208Tl) in lead shield Flux from rocks(0.5 Bq / kg) and concrete (5 Bq / kg) @ LNGS: 3.5 ·107 / (m² d) [BOREXINO, Laubenstein] New lead for shielding under study with GEMPI @ LNGS: <30 Bq / kg

  30. Wavelength shifter Reflector (VM2000) 232Th (208Tl): no vs. active suppr.  Lead Simulation for 30 Bq/kg, inner-Ø: 2m, height: 2 m

  31. Ge for DM • Conventional diodes (“pragmatic approach”): no event-by-event discrimination  reduction of background  annual modulation signal (mass!) • Cryo-detectors (“sophisticated approach”: Edelweiss, CDMS): event-by-event discr. heat Thermometer (NTD Ge) Ge Crystal T~20mK ionization

  32. Ge for DM – next generation cryogenic detectors

  33. Ge for DM - GeLN Charge read-out only 300 kg y, 1E-3/ kg y keV Baudis et al. NIM A 426 (1999) 425 GENIUS (12 m diameter)

  34. Ge for DBD – potential of cryodetectors EDELWEISS: identification of alphas by their anomalous quenching factor

  35. Conclusion: Multi-Purpose Detectors for DM/DBD/SOL ? • Xe: DM-det.  DBD-det.  Solar-det. Solar-det  DM-det (isotope separation) • Ge: DBD-det  DM-det (convent./cryo.)  Multi-Purpose Targets!Appealing, since technological and experimental aspects similar

  36. Bob Lanou LowNu2003: To quote from a great philosophe Francaise: “MIEUX VAUT FAIRE UNE CHOSE BIEN PLUTOT QUE D’EN FAIRE PLUSIEUR MOINS BIEN.” Advanced genetic engeneering: Eier legende Wollmilchsau (oviparous wool-milk-pig) Catherine Deneuve in “Belle de Jour” Question of style ….

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