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Path Towards A Large Scale

Workshop on Next Generation Dark Matter Detectors University of Chicago, Chicago, 9-10 December, 2004. Path Towards A Large Scale. Detector. Ilan Levine Indiana University South Bend For the PICASSO collaboration. E. Behnke, W. Feighery, M. Henderson, I. Levine, C. Muthusi, L. Sawle

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Path Towards A Large Scale

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  1. Workshop on Next Generation Dark Matter Detectors University of Chicago, Chicago, 9-10 December, 2004 Path Towards A Large Scale Detector Ilan Levine Indiana University South Bend For the PICASSO collaboration

  2. E. Behnke, W. Feighery, M. Henderson, I. Levine, C. Muthusi, L. Sawle Indiana University South Bend, South Bend, IN, USA G. Azuelos, M. Bernabé-Heider, M. Di Marco, P Doane, M.H. Genest, R. Gornea, R. Guénette, C. Leroy, L. Lessard, J.P. Martin, U. Wichoski, V. ZacekUniversité de Montréal, Montréal, Canada S. N. Shore, Dipartimento di FisicaUniversità di Pisa, Pisa, Italy K. Clark, C. Krauss, A.J. NobleQueens University, Kingston, ON, Canada R. Noulty, S. KalanalingamBubble Technology Industries, Chalk River, ON, Canada F. d’Errico Yale University Medical School, New Haven, CT, USA Collaboration agreements signed with: France, Portugal + Czech Republic + …..

  3. Recoiling 19F creates microscopic vapour cavities. If Rcavity>R ”critical”, Phase transition irreversible. ~Half thermal PE released acoustically Adjust pressure (and superheat) Temp Control Metastable Superheated Freon droplet, suspended in gel B Freon bubble A WIMP/19F elastic scatter D Freon bubble Acoustic sensor, preamp, daq C E

  4. 2000 Exposure 106 g *d Overburden: 6.7m rock 2004 Exposure ~1 kg *d Overburden: 2000m rock ~500 cts/d/kg a contamination 2005 Exposure ~140 kg *d 200 cts/d/kg a contamination Exposure ~1400 kg *d 20 cts/d/kg a contamination Exposure ~14000 kg *d 0.2 cts/d/kg a contamination

  5. A • Changing and measuring T • Gel Composition • Minimize repressure time • Life • Radiopurity • PICASSO/SIMPLE/ E.-G. • Total Active Target • Edge effects • Dissolved gas effects • Containers

  6. Determination of Active Mass • Microscope • Calibr. neutron - beam • Weighting • Simulation of response Cb26 5014 n-beam/ Microsc. DF37 DF68 C [cts/gram x neutron/cm2] Cb24 4437 n-beam/ Microsc. Mb29 Cb28 Cb27 1 MC 2 2 2 3 1 2 2 4 Average: C=0.1100.005 cts/g n cm-2 (2red = 1.5) 2 Four different methods give consistent result!

  7. Evolution of containers: Larger & Cleaner ~1 L 4.5 L 8ml SNO polypro. 8g/detector Acrylic 40g/detector

  8. B • Non-WIMP induced transition • Cosmic ray related • Local radioactivity sources • Internal radio-contamination, • LET(&RET?), recoil threshold function • Target:Pb or I doping to enhance coherent X-sect.? • Calibration of larger detectors (30L)

  9. Background Evolution of 1l Detectors Metallic components, unpurif. CsCl: 30 cts/g/d Purified CsCl: 2.5 cts/g/d • Purification & fabrication in UdeM clean room • no metals in contact with solution • non-metallic lid during fabrication • CsCl & other gel ingredients cleaned with HTiO • Freon distilled

  10. Data taking at SNO 2nd generation Alpha – particle background 3rd generation (Cleanroom) Status: Neutralino  =5 pb, 50GeV

  11. (neutron calibrations)  = 90% Nuclear recoils  = 50% 1 MeV  - particles 100 keV -recoils 1 keV Mips -electrons ,  10 eV BD 100 T(oC): 5o 25o 40o « Foam limit BD 1000 T(oC): 30o 45o 60o

  12. Detector Response & Calibration • SBD’s are threshold detectors! • Calibration of energy response with monochromatic neutrons from 7Li(p,n) reaction F En = 100keV dN/dEREC 20 10 30 EREC (keV) ETH(450) ETH(350) Measurements at 5 MeV UdeM tandem accelerator

  13. C • Acoustic Attenuation • Geometrical dependences • Submergible sensors • Signal/Noise • Other signals of transition? (Cherenkov? Scintillator?) • Trigger criteria at high superheat All data (bubbles, doors, internet, cell phone, coughs!) Only bubbles Thickness mode Piezo element

  14. Filter acceptance: Raw /passed events Acceptance Temperature [oC]

  15. D • False phase transitions • Electronic noise • Environmental signals (e.g. blasting) • Decompression events • Event 3-D localization

  16. Digital filter Digital Filtering of the data

  17. E • Formalize Analysis • “Blind” Analysis • Separate analysis teams • Extend MC model (shielding, externalMIPS, etc) • Collaboration Growth (10kg detector and beyond) and phased plan.

  18. Monte Carlo Simulation of Detector Response Input: • Detector loading • droplet size distribution • Emin(T), P(E, Eth) • GEANT 4 V4.5.2 ½ • Neutron code ENDF/B • nuclear stopping power model ICRU_ R49 • electronic stopping power model SRIM 2000p 400 keV neutrons

  19. The Future in Three Phases: Phase 1: reach DAMA Phase 2: reach tip of MSSM predictions Phase 3: reach core of MSSM predictions

  20. Conclusions Check entire DAMA region in 2005! Growth of collaboration: Univ. de Paris & Univ. Di Lisboa (SIMPLE) Czech Tech. U. of Prague , Yale, BTI Phased growth of detector and techniques to enter MSSM phase space soon. Most covered before 2010. R&D new modules 3 –30 litres Excellent rating of LOI (including phased approach) by Exp. Advisory Commitee. Next stage is full proposal for large scale detector

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