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The Enriched Xenon Observatory for Double Beta Decay Francisco LePort Stanford University 6/11/07 Francisco LePort 1 #;<%%""$


  1. The Enriched Xenon Observatory for Double Beta Decay Francisco LePort Stanford University 6/11/07 Francisco LePort 1

  2. #;<�����������%%����"��������������"��$ #;<�����������%%����"��������������"��$ ������������� ������������� �� �� ��������������������� ��������������������� �� ������������������������� �!� !� �������������������������������"������������ �������������������������������"������������ �� ������������������������� � �� #����$��������$����������������������� ν ν %����� %����� ν ν ������� ������� �� #����$��������$����������������������� &������� ν &������� ν �"���������� �"���������� ± ± � � σ σ �����"������������������������'()�� �����"������������������������'()��*�+ *�+ �������� �������� , , ± ± ± ± ± ± (� -���%���� νββ νββ . . �/� 0�1 1�� �� �� �� $��2 $��2!������� !������� �����'������������� �����'������������� (� -���%���� �/� 0� ?��� *��� #%%' 3��� σ # /#�F� � νββ . �/� *�D����� ���� � ν .��� �')*�+ 2���� 2�� !��������� 2$�7� 2��+� 2$�� 2�� 6��?5� 2�"����� E34� A C&* B ?�����"� � 8� ) �'� 9 �')�2������ �9�� �8 )� �� ��"� �������� �� 8� �� � @ �'8�2������ ('�9�� �� �� �) "� , 3������ 3������ �����'�4�$��3�"�5���6�7��)�����2���8� �����'�4�$��3�"�5���6�7��)�����2���8� , 9 σ 2#�/#�:��'(��������������#;<�3=>7�?�����������4�$��3�"�!� ���2�������)(��� 9 σ 2#�/#�:��'(��������������#;<�3=>7�?�����������4�$��3�"�!� σ σ σ σ ���2�������)(��� σ σ @ σ 2#�/#�:��'����������������������������"�������������������������������������� ������������� @ σ 2#�/#�:��'����������������������������"������������������������� σ σ σ σ σ σ ���������������� ���������������� A 3�����������4�$��3�"�?����2�������((��� 3�����������4�$��3�"�?����2�������((��� A B ?������������'� ?������������'�C��� C��� 4�$�����)(�2�666��68�� 4�$�����)(�2�666��68�� B 6/11/07 Francisco LePort 2

  3. Multiple Paths to a Background Free Detector EXO High Cryogenic Pressure Liquid Gas TPC TPC Ba Identification Ba Ba Identification in High- Identification in low-pressure Pressure Gas in Liquid Gas 6/11/07 Francisco LePort 3

  4. Detection Method Overview [M. Moe, Phys. Rev. C 44 (1991) R931] 136 Xe → 136 Ba ++ + 2e - (+ 2 ν e ) Ion grabber/mover Optical Spectroscopy of Ba+ Xe TPC e e - - e e - e - - 6/11/07 Francisco LePort 4

  5. EXO-200 Goals • Search for 0 νββ in 136 Xe with competitive sensitivity • Measure 2v ββ half life of 136 Xe (best limit currently set by Bernabei et al, 1x10 22 y) • Understand the operation of a large LXe detector – Understand backgrounds / characterize detector materials – Learn about large scale Xe enrichment – Understand Xe handling, purification, resolution 6/11/07 Francisco LePort 5

  6. EXO-200 Detector Improve energy resolution via simultaneous collection of ionized electrons and scintillation light (confirmed by others) E. Conti et al. (EXO Collab), PRB: 68 (2003)054201] Ionization and Scintillation results using 207 Bi 6/11/07 Francisco LePort 6

  7. EXO-200 TPC APD plane (copper) and acrylic supports grid plane (photo-etched Central HV plane (photo- (one holds the field divider phosphor bronze) etched phosphor bronze) resistor chain) field shaping rings (copper) teflon light flex cables on back of APD plane reflectors/diffusers (copper on kapton, no glue) 6/11/07 Francisco LePort 7

  8. Detector Components 6/11/07 Francisco LePort 8

  9. Chamber Chamber is fully designed and being machined at Stanford University under 7 m.w.e shielding E-beam welding will be used for all but final weld to minimize introduction of radioactive background 6/11/07 Francisco LePort 9

  10. The EXO-200 detector double walled vacuum insulated 200 kg of LXe in thin vessel cryostat (ultra pure copper, 1.5 mm thick) (ultra pure copper, 2.5 cm thick) 50 cm of ultra pure cryofluid, providing large thermal bath for uniform temperature and excellent screening from external γ rays (density = 1.8 at -100 C) (3M HFE-7000, hydrofluoroether C3F7OCH3) 6/11/07 Francisco LePort 10

  11. The EXO-200 detector class 100 clean room Refrigeration and hermetic lead enclosure HFE feedthroughs (25 cm, low Pb-210 activity) 6/11/07 Francisco LePort 11

  12. Electronics -Fully designed and in production -DAQ software has been written -Fine tuning of shaping times and other parameters underway 6/11/07 Francisco LePort 12

  13. 136 Xe stockpile i 136 Xe stockpile in n shipping container shipping container 200 kg of xenon enriched to 80% in 136 Xe : the largest isotope possession by any ββ collaboration 6/11/07 Francisco LePort 13

  14. APD and Electronics commissioning • Test 16 APDs simultaeously using a Xe scintillation source and an 55 Fe source • Full DAQ chain in use (HV board, FEC, TEM, Linux PC with DAQ software) 6/11/07 Francisco LePort 14

  15. Commissioning LXe and Refrigeration Systems In April, successfully liquefied 30 kg of Natural Xe in a “dummy” stainless steel vessel! 6/11/07 Francisco LePort 15

  16. The EXO-200 #;<G��������������� modular clean rooms ���������������������% ���������������� ������� %���J������������ &������� ��������� ����������%���?������ >������� ��%������������������ ���G�������$������������� HI#�������������� ��������������������� 6/11/07 Francisco LePort 16

  17. muon flux at WIPP (~ 1700 m.w.e.): 4.77 × 10 -3 m -2 s -1 EXO-200 (3.10 × 10 -3 m -2 s -1 sr -1 , ~15 m -2 h -1 ) [E.-I.Esch et al., Nucl. Instr. Meth. A 538(2005)516] ★ underground at WIPP 6/11/07 Francisco LePort 17

  18. Materials qualification database • Neutron Activation Analysis (NAA) - Alabama (MIT reactor) • ICP-MS and GD-MS - INMS (Ottawa) • Radon emanation - Laurentian (Sudbury) • Gamma counting - Neuchatel, Alabama • Alpha counting - Alabama, Carleton, SLAC, Stanford ~ 330 entries 6/11/07 Francisco LePort 18

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