r&d for future zeplin
DESCRIPTION
R&D for Future ZEPLIN. D.B. Cline, W.C. Ooi, F. Sergiampietri(a), H. Wang, P. Smith(b), X. Yang Physics and Astronomy, UCLA , (a) Pisa, (b) RAL&UCLA. J.T. White, J. Gao, J. Maxin, G. Salinas, R. Bissit, J. Miller, - PowerPoint PPT PresentationTRANSCRIPT
R&D for Future ZEPLINM.J. Carson, H. Chagani, E. Daw, V.A. Kudryavtsev,
P. Lightfoot, P. Majewski, M. Robinson, N.J.C. Spooner
University of Sheffield
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
D.B. Cline, W.C. Ooi, F. Sergiampietri(a), H. Wang, P. Smith(b), X. Yang
Physics and Astronomy, UCLA , (a) Pisa, (b) RAL&UCLA J.T. White, J. Gao, J. Maxin, G. Salinas, R. Bissit, J. Miller, J. Seifert
Department of Physics, Texas A&M University T. Ferbel, U. Schroeder (Chemistry), F. Wolfs, W. Skulski,
J. TokeDepartment of physics and Astronomy, Rochester University
Y. GaoSouthern Methodist University, Texas
Presentation outline
• Introduction• Detector geometry • Principles of operation - characteristics of an event• Light collection• Signal readout - charge gain in liquid xenon• Dark Matter limit• Program for R&D
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
IntroductionOur goals:• Large mass of sensitive LXe in a scale of Tonnes• Simple detector geometry • Very low background radiation• Sensitivity to very low energy events - possibility of few photons detection - large surface photocathode - possibility of few electrons detection -> Both requires high gain in liquid
Large mass with maximum surface acting as a photocathode : SPHERICAL GEOMETRY
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
LXe physical properties• Energy/scintillation photon W_ph =21.6 eV • Scintillation Absorption length > 100 cm• Energy/el-ion pair: W=15.6 eV• Saturation velocity of electrons from E=3 kV/cm: v=2.6 mm/s• Threshold electric field for proportional
scintillation: E=400-700 kV/cm• Threshold electric field for electron multiplication: E~1 MV/cm• Maximum charge gain measured 200-400
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
(table from T.Doke NIM 196 (1982) 87)
Spherical TPC filled with LXe
Outer sphere
Photocathode coated with CsI
Central ball with charge readout Field shaping rings
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
Detector structure
Central ball 4 covered with charge collecting and amplifying micro-structure
•Sensitivity to single electron•High readout segmentation for position information
Requirements:
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
Electric field distributionCan detector operate with a non uniform
field ?
Electron drift velocity = f (E)
3 kV/cm
(L.S.Miller at al. Phys. Rev. Vol. 166, 1967)
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
Charge and light yield = f (E)
Measured charge and light yield for E<5 kV/cm
Extrapolation to E<75 kV/cm(Thomas-Imel model Phys.Rev A 38 (1998)
5793) (T.Doke et al. Jpn.J.Appl.Phys. 41 (2002) 1538)
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
(E.Aprile et al. astr-ph/0601552)E= 3 kV/cm
5e/keVr@ 2KV/cm
Charge and light readout
• Scintillation light photons converted into photoelectrons from the CsI photocathode
- CsI QE ~ 30 % @ E>3 kV/cm (E.Aprile et al. NIM A 343, 1994) - 4 coverage except shadowing
• Ionisation electrons and photoelectrons readout with segmented charge amplifying device delivering energy and position information
- low primary charge sensitivity with charge gain
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
Charge amplification in LXE
Conditions for electron multiplication and secondary scintillation in liquid xenon :
Electric field threshold for avalanche development : ~ 1MV/cm
Electric field threshold for proportional light: 100-150 kV/cm (B.A. Dolgoshein et al. JETP Lett. Vol. 6, 1967)
400-700 kV/cm (K.Masuda et al. NIM 160, 1979)
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
H.Wang 1991, gain : 40
Event generation (1)
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
Event generation (2)
Interaction in the sensitive volume
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
Event generation (3)
Simultaneous creation of scintillation UV light and …
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
Event generation (4)
… creation of ionisation charge
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
Event generation (5)
Scintillation UV photons converted into photoelectrons
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
Event generation (6)
First pulse generated
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
Event generation (7)
Proportional scintillation UV photons converted into photoelectrons
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
Event generation (8)
Second pulse generated
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
Event generation (9)
First after–pulse generated
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
Event generation (10)
Second after–pulse generated and pulses generation continues …
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
Light collection MC calculations
•Energy to produce UV photon: W= 21.6 eV
•Light attenuation length: 100 cm
•CsI QE : 20, 30 %
•Electron lifetime: 0.5, 1 and 5 ms
Shadowing
3D example:
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
MC calculations: results
At R=50 cm, light collection = 4-7.5 phe/keV
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
Charge amplification - wires
S.E Derenzo et al. Phys. Rev. A Vol 9,1974 maximum gain : 400
M.Miyajima et al. NIM Vol 134 ,1976 maximum gain : 100
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
Readout wires
Problems with gain in liquid
• Slow motion of avalanche ions building space charge
• Local imperfections of the readout structure
• Purity of LXe
• Large amount of created UV photons causing after-pulses leading to discharge
• Bubble formation on the sharp edges of the readout electrode hence conducting path creation(J.G. Kim et al. NIM A 535 2004)
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
Charge readout - microstructures
Micropattern detectors :• micromegas• micro-dot• MSGC (already used in LXe with gain =10) (A.P.L. Policarpo et al. NIM A 365 1995)
Already used in LAr (no gain due to discharges)
Cold field emission device:
High electric field ~ 1MV/cm with small differential voltage
(J.G. Kim et al. NIM A 535 2004)
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
Charge readout – simulation (1)
Tools: Garfield (Analytic) by R.Veenhof (CERN) Maxwell (FEM) by Ansoft
Electric field near wire surface
Recalculated LXe gain in single wire chamber
Townsend coefficient from S. Derenzo et al. Phys. Rev. A Vol 9,1979 (large errors)
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
Charge readout - simulation (2)
Microstructure modelling
What is needed :
• Local high electric field for high gain
• 100 % 4 charge collection
• Electric field < 400 kV/cm when V_cath=0 and E_drift = 75 kV/cm
Drift field
75 kV/cm
5 kV/cm
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
Charge readout – simulation (3)
Simulated multiplication Electric field strengthon the axis of the cell
75 kV/cm
0 V at the cathode
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
How to avoid feedback pulses ?
Using HV switch : When V_cath = 0 E_max < 400 kV/cm
Field on the cell axis:
Field at the cell entrance:
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
Dark Matter Limit
Assumptions:• LXe mass: 1 Tonne• Run period: 1 year• Energy range: 4-50 keVnr
O events detected
1O events detected
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006
Backgrund sources in 1 Tonne LXe detector:(M.Carson et. al. NIM A 548 (2005) 418)
A)222 Rn events/year: 1.46*10^6B) PMTs (Hamamatsu R8778) events/year: 3.65*10^5C) 85 Kr events/year: 9.1*10^5
R&D program (goals to achieve)
• Study of the scintillation properties of LXe at high electric field (scintillation light and
charge yield)
• Study of the electric field threshold for proportional light creation
• Explore possibility of the high gain in LXe using micro-structure devices
(study of the limitations: maximum gain, stability in time, energy resolution)
• Work on the feedback pulses suppression
Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006