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Performance and Physics with the CsI(Tl) Array at the Kuo-Sheng Reactor Neutrino Laboratory

Performance and Physics with the CsI(Tl) Array at the Kuo-Sheng Reactor Neutrino Laboratory. V. Singh (On behalf of the TEXONO Collaboration) IoP, Academia Sinica, Taipei, Taiwan. Physics with CsI(Tl) detector Period -2 configuration Data analysis ※ Cuts

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Performance and Physics with the CsI(Tl) Array at the Kuo-Sheng Reactor Neutrino Laboratory

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  1. Performance and Physics with the CsI(Tl) Array at the Kuo-Sheng Reactor Neutrino Laboratory V. Singh(On behalf of the TEXONO Collaboration) IoP, Academia Sinica, Taipei, Taiwan • Physics with CsI(Tl) detector • Period -2 configuration • Data analysis ※Cuts ※Cut summary (central crystals) • Results (Prilim.) • Background • Status and plans • Summary

  2. Physics with CsI(Tl) detcetor n physics full of surprises , need intense n-source Reactor : high flux of low (MeV range) energy electron anti-neutrinos ne + p e+ + n Reactor n-spectrum has been measured (~2% in the 3 - 7 MeV)For (ne-e), both NC & CC and their interference term contribute g

  3. Physics with CsI(Tl) detcetor Investigations of (ne-e) cross-sections with reactor ns To study : Electro-weak parameters (gv, gA, Sin2qW) at the MeV range CC & NC interference anomalous n magnetic moments and mean square charge radius NCEX on nuclei by nne + (A,Z) ne + (A,Z)* NOT observed at lower energies !CsI(Tl) have good g resolution and capture efficiency & suitable to study these processes.

  4. KS Expt. : Period II Configuration Period II : Jan.28, 2003 – Jan.08 2004 ( ~ 50 days OFF) Shielding & Veto [one side] CsI(Tl) Array (186 kg)

  5. KS Expt: Period II CsI(Tl) Detector Connecting Board CsI(Tl) [ 186 kg ] Flash ADC Readout Multi-Disks Array [800 Gb] [16 ch, 20 MHz, 8 bit]

  6. Reactor Neutrino Interaction Cross-Sections P2: SM (ne) > 2 MeV P1: MM (ne) 1-100 keV P3+: Coh. (nN) < 1 keV

  7. KS/P-2/CsI(Tl)/Cross-Section Data • Data Volume:  Total more than 250 / 50 days ON/OFF • CsI(Tl) Performance:  186 kg mass (Future target 500 kg mass)  FWHM energy resolution of 10% @ 660 keV Z-position resolution is 2cm @ 660 keV  Range of O(0.0048 cpd) [counts kg-1 day-1 10keV-1] @ 3 MeV background • Analysis:  Cosmic Veto (5 ms gate)  Anti-Compton (Whole Ge detector assembly + Rest CsI(Tl) crystals)  Pulse Shape Disc. (Alphas, elect. noise, accidentals etc.)

  8. CsI(Tl) crystal layout

  9. Period-2 CsI(Tl) Array : 186 kg, 93 crystals Single Crystal QL Vs QR (Raw Data) Z = 0 cm Z =40 cm 208Tl 40K 137Cs Region of Interest for SMs(ne)

  10. Data Analysis Techniques No Cut: Energy Spectrum Defining Cuts: 1] General Cuts –a) No Cut energy spectrumb) Single Event Hit & Single Crystal Hit c) Cosmic ray Cut SEH, SCH SEH, & SCH SEH, SCH, & Cosmic SEH, SCH, Cosmic-ray, & Z-pos SEH, SCH SEH, SCH SEH, SCH

  11. Data Analysis Techniques Normal Event Pulse Alpha Event Pulse Defining Cuts:2] Special Cuts – a) Alpha Event Cut(having fast decay time) Check- Alphas are located around 2 MeV Select- event having Time average less than 40 A; .

  12. Data Analysis Techniques Defining Cuts:3] Special Cuts – b) Very narrow Event Cut(Very fast decay time) Select- event having partialcharge less than 3 Note- Not in all crystals.

  13. Data Analysis Techniques Defining Cuts:4] Special Cuts – c) Double Pulse Cut Select – Event havingLarger Time Avg.but low charge ! A; Right side Double Pulse

  14. Data Analysis Techniques 40cm long crystal No cut Defining Cuts:5] Z-position Cut – Select – Both side peak mean initially taken as 0 & 40 ! 0 cm 40 cm Narrow Pulse Normal Pulse AlphaPulse

  15. Cut Summary of Central Crystals Cut type Over all energy Above 3 MeV (%) (%)[1] Cosmic ray 11 88 [2] anti-Comp. 70 86[3] Single Tri. 01 02[4] 1+2+3 72 95 [5] Alpha+Narrow 10 83[6] Double Pulse 11 38[7] PSD 25 95[8] All Cuts 32 96 * Z-position cut is not applied !!

  16. Period-2 CsI(Tl) Array : Results (prilim.) Narrow Pulse Peak Alpha Peaks Z-positon of Alpha Energy Spectrum of Alpha and narrow pulse

  17. Period-2 CsI(Tl) Array : Results (Prilim.) 211 kg-days Energy Spectrum of recoil electron 137Cs (661 keV) 40K (1461 keV) * 16 Central Crystals * Mass 32 kg * Data set 6.9 days OFF period 208Tl (2615 keV)

  18. Period-2 CsI(Tl) Array : Results (Prilim.) The Estimate of BKG Suppression >3 MeV * Cosmic ~ one order * From Veto to All Cuts> Two order * 100kg All Cuts to ON-OFF ~ One order * S/B ratio (integral > 3 MeV) = 1/10 Differential Event Count for CsI(Tl)

  19. BKG in CsI(Tl) detcetor Internal intrinsic radioactivity:Multi-structure in Alpha spectrum (study is underway) Concentration of 137Cs = 1/e *( 2.14 x 10-18 ) g / g * e is more than 0.5

  20. Status and Plans Attempt measurement of Standard Model s(nee-)  sin2qw at MeV range Analysis: [1]  Central 16 crystals gone well To study alpha spectrum Need more attention a) Energy resolution b) Z-position  Rest 15 (40cm) is next step  Rest 10 (40cm) and 17 (20cm) is second next step Future Upgrades and Modifications of the Expt.:  Goal of achieving a 500 kg system  Improvements of Shielding  More Physics Data Taking To investigate complementary detection techniqueTo study the other unexplored channels

  21. Summary Present Results:Bkg ~ 10- 3 kg-1day-110 keV-1 at 3 MeVON - OFF ~10- 4 kg-1day-110keV-1at 3 MeV S/B ratio = 1/10 After analyzing all crystals and after ON - OFF Data, we will present better results ! Thanking you for your kindattention !

  22. Cut Summary of Central Crystals [01]= Cry. #, [02]= Cosmic, [03]= Single Cry., [04]= Single Tri., [05]=Cos+Sc+St, [06]= Alpha+Narrow, [07]= Wrong ipos, [08]= Double Pulse, [9]= PSD, [10]= All cuts

  23. Cut Summary of Central Crystals ( > 3 MeV) [01]= Cry. #, [02]= Cosmic, [03]= Single Cry., [04]= Single Tri., [05]=Cos+Sc+St, [06]= Alpha+Narrow, [07]= Wrong ipos, [08]= Double Pulse, [9]= PSD, [10]= All cuts

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