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Rare decay

Rare decay. Opportunities at U-70 Accelerator (IHEP, Protvino). Experiment KLOD. Joint Project : IHEP, Protvino JINR, Dubna INR, Moscow, RAS. STATE RESEARCH CENTER OF RUSSIA INSTITUTE FOR HIGH ENERGY PHYSICS. theoretically. Rare FCNC process Purely CP-Violetting (Littenberg, 1989)

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Rare decay

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  1. Rare decay Opportunities at U-70 Accelerator (IHEP, Protvino) Experiment KLOD Joint Project : IHEP, Protvino JINR, Dubna INR, Moscow, RAS

  2. STATE RESEARCH CENTER OF RUSSIA INSTITUTE FOR HIGH ENERGY PHYSICS

  3. theoretically • Rare FCNC process • Purely CP-Violetting(Littenberg, 1989) • Totally dominated from t-quark Computed in QCD(Buchalla, Buras, 1999) Small corrections due to mt • <π|Hweak|K> is known from K+0 e+e (Ke3) No long distance contribution (Rein, L. M. Sehgal, 1989; Marciano, Z. Parsa1996) • SM: Br ~ η2, CP violating parameter (Buchalla, Buras, PR, 1996) • Sensitive to the new heavy objects New physics Theoretically clean process, ~1% SM:Br = (2.8±0.4)×10−11 (Buras et al., hep-ph/0603079)

  4. Experimental challenge. Must-do experiment signature: π0-signal + “nothing” At least 2 charged or 4 γ’s -- veto inefficiency ~ 10-6 -- full veto covered π0 in 34% of decays -- PT cut(231MeV/c) Interaction with gas -- high vacuum Strategy: 2 γ’s in Ecal No veto-signal Construct π0 from 2 γ’s -- reconstruct vertex -- reconstruct PT (narrow beam approach)

  5. KLbeam at U-70 IHEP Beam requirements -- very narrow (R<5cm) and well collimated -- high PT balanced -- high intensity (~108 KL/pulse) -- mean KL energy ~10 GeV -- minimal contamination of neutral unwanted particles (neutrons/KL < 10) Sketch design completed ! KLbeam optimization conditions -- 1013 60 GeVp/cycle (slow extraction); -- Cu-target 25см (80% interactions); - 35 mrad extraction angle; - 5 cm Pb-converter: - steel collimators

  6. KLbeam at U-70 IHEP Beam requirements -- very narrow (R<5cm) and well collimated -- high PT balanced -- high intensity (~108 KL/pulse) -- mean KL energy ~10 GeV -- minimal contamination of neutral unwanted particles (neutrons/KL < 10) Sketch design completed ! KLbeam optimization conditions -- 1013 60 GeVp/cycle (slow extraction); -- Cu-target 25см (80% interactions); - 35 mrad extraction angle; - 5 cm Pb-converter: - steel collimators

  7. KLbeam. Calculated parameters Background & Fluxes per spill

  8. KLOD Detector Layout Vacuum requirement: ~(10 –3 -- 10 –4) torr inside tank ~ 10 –7 torr inside internal membrane Another solutions under study Forward Veto Section Main Veto Veto Hodoscope Forward Calorimeter Backward Veto Section

  9. KLOD Detector Layout Vacuum requirement: ~(10 –3 -- 10 –4) torr inside tank ~ 10 –7 torr inside internal membrane Another solutions under study Forward Veto Section Main Veto Veto Hodoscope Forward Calorimeter Backward Veto Section

  10. KLOD Detector Layout Vacuum requirement: ~(10 –3 -- 10 –4) torr inside tank ~ 10 –7 torr inside internal membrane Another solutions under study Forward Veto Section Main Veto Veto Hodoscope Forward Calorimeter Backward Veto Section

  11. KLOD Detector Layout Vacuum requirement: ~(10 –3 -- 10 –4) torr inside tank ~ 10 –7 torr inside internal membrane Another solutions under study Forward Veto Section Main Veto Veto Hodoscope Forward Calorimeter Backward Veto Section

  12. KLOD Detector Layout Vacuum requirement: ~(10 –3 -- 10 –4) torr inside tank ~ 10 –7 torr inside internal membrane Another solutions under study Forward Veto Section Main Veto Veto Hodoscope Forward Calorimeter Backward Veto Section

  13. KLOD Detector Layout Vacuum requirement: ~(10 –3 -- 10 –4) torr inside tank ~ 10 –7 torr inside internal membrane Another solutions under study Forward Veto Section Main Veto Veto Hodoscope Forward Calorimeter Backward Veto Section

  14. Main Veto (1) “Shashlyk” – calorimeter (0.3mmPb + 1.5ммmolding Scint.) • 30000 photonsper 1 GeV-shower • 5.5 ph.e–per single Sc. platefor mip • 18 ph.e–per1 MeV of “visible” energy • E/E3%/sqrt(E) Mirrored Module size along the beam Module size across the beam Scintillator thickness Lead thickness Radiation length, X0 Module length (active part) Module full length Module weight Fibers length (per module) # modules in Main Veto Fibers length in Main Veto 300 mm 200 mm 1.5 mm 0.275 mm 35.5 mm 500 mm 600 mm 80 kg 268 m 1400 375 km Segmentation along the beam – 100 mm Segmentation across the beam – 200 mm 0.55 mm for the rear part 17.75 mm for the rear part (355 + 145) mm, (10 + 8) X0 Without photodetector All loops including (28 – across beam) х (50 – along beam) Loops

  15. Main Veto (1) “Shashlyk” – calorimeter (0.3mmPb + 1.5ммmolding Scint.) • 30000 photonsper 1 GeV-shower • 5.5 ph.e–per single Sc. platefor mip • 18 ph.e–per1 MeV of “visible” energy • E/E3%/sqrt(E) Mirrored Module size along the beam Module size across the beam Scintillator thickness Lead thickness Radiation length, X0 Module length (active part) Module full length Module weight Fibers length (per module) # modules in Main Veto Fibers length in Main Veto 300 mm 200 mm 1.5 mm 0.275 mm 35.5 mm 500 mm 600 mm 80 kg 268 m 1400 375 km Segmentation along the beam – 100 mm Segmentation across the beam – 200 mm 0.55 mm for the rear part 17.75 mm for the rear part (355 + 145) mm, (10 + 8) X0 Without photodetector All loops including (28 – across beam) х (50 – along beam) Loops

  16. Main Veto (2)

  17. In Beam Veto Calorimeter Hadron Blind Calorimeter ? 1-st idea:to use Cherenkov light quartz fibers are only sensitive to em shower component CMS HF: e/h ~ 5, NIM A399 (1997) 202 2-nd idea:Dual Readout (Scint.+Ch.) DREAM calorimeter, NIM A536 (2005) 29 Purpose is to measure fem event by event & eliminate dominant source of fluctuations for hadrons. They succeed ! Not our goal ! But... -- look at Ch/Sc signals ratio & its behavior in transverse and longitudinal directions Possible problem : not enough Ch. light => 45 deg. turn => more quartz fibers (more loose structure) The goal is not to measure E but to identify γ’s Not Hadron-Blind but Hadron-Distinguishable Calorimeter Suitable for our goal prototype is under construction

  18. In Beam Veto Calorimeter Hadron Blind Calorimeter ? 1-st idea:to use Cherenkov light quartz fibers are only sensitive to em shower component CMS HF: e/h ~ 5, NIM A399 (1997) 202 2-nd idea:Dual Readout (Scint.+Ch.) DREAM calorimeter, NIM A536 (2005) 29 Purpose is to measure fem event by event & eliminate dominant source of fluctuations for hadrons. They succeed ! Not our goal ! But... -- look at Ch/Sc signals ratio & its behavior in transverse and longitudinal directions Possible problem : not enough Ch. light => 45 deg. turn => more quartz fibers (more loose structure) The goal is not to measure E but to identify γ’s Not Hadron-Blind but Hadron-Distinguishable Calorimeter Suitable for our goal prototype is under construction

  19. In Beam Veto Calorimeter Hadron Blind Calorimeter ? 1-st idea:to use Cherenkov light quartz fibers are only sensitive to em shower component CMS HF: e/h ~ 5, NIM A399 (1997) 202 2-nd idea:Dual Readout (Scint.+Ch.) DREAM calorimeter, NIM A536 (2005) 29 Purpose is to measure fem event by event & eliminate dominant source of fluctuations for hadrons. They succeed ! Not our goal ! But... -- look at Ch/Sc signals ratio & its behavior in transverse and longitudinal directions Possible problem : not enough Ch. light => 45 deg. turn => more quartz fibers (more loose structure) The goal is not to measure E but to identify γ’s Not Hadron-Blind but Hadron-Distinguishable Calorimeter Suitable for our goal prototype is under construction

  20. Monte-Carlo Resolutions -- σ(Z) ≈ 15 cm(without beam contribution) Dominated by FCal energy resolution -- σ(PT) ≈ 6 MeV/c Defined by beam angular spread

  21. Background & Sensitivity Estimation Main cuts • E(1), E(2)> 0.15 GeV better FCal performances, γ’s from excitation • E(1), E(2) < 6 GeV • Pt> 120 MeV/c • Reconstructed Vertex inside Main Decay Volume • γ’s pointed to the reconstructed Vertex (+/- 0.5 m) works for γ’s not from one π0 • Energy gravity Center > 20 cm from beam axis • Dist(γ1-γ2) > 15 cm accidentals, γ’s from different π0’s For 1 SM decay KL 0.1 Br = 5.7 x 10-4 KL00~ 0.26 Br = 9.1 x 10-4 Max(Pt)=209 МэВ/c KL000 0.1 Br = 21.6% Max(Pt)=139 МэВ/c KL- е+  0.1 Br = 38.7% Acceptance – 18 (15) % 4.8% KL decays in Main Volume @ 108 (5.4×107) KL/spill 10 days sensitivity (~ 104 spills/day) 10×(104)×(108)×(4.8×10-2)×(1.8×10-1)×Br(2.8×10-11)≈ 2.4events 10×(104)×(5.4×107)×(4.8×10-2)×(1.5×10-1)×Br(2.8×10-11)≈ 1.1events

  22. Summary. •It is possible to make registration of K0 → π0νν(bar)decaysat IHEP setup . • Sensitivity of setup allows for reasonable time (100 days) to register about 30 (SM) decays at a level of a background nearly 9 decays. • R&D for production and test prototypes of the basic detectors is necessary. Some of detectors were tested and the results coincide with calculations. • The further simulation for more exact calculation of signals and background processes is necessary.

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