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Beam Catcher in the KOPIO experiment

Beam Catcher in the KOPIO experiment. Hideki Morii (Kyoto Univ.) for the KOPIO collaborations. Contents What is Beam Catcher? Basic Design Expected Performance Aerogel Quality Control System. 1. What is Beam Catcher?. Beam Catcher in the KOPIO experiment.

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Beam Catcher in the KOPIO experiment

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  1. Beam Catcher in the KOPIO experiment Hideki Morii (Kyoto Univ.) for the KOPIO collaborations • Contents • What is Beam Catcher? • Basic Design • Expected Performance • Aerogel Quality Control System Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop

  2. 1. What is Beam Catcher? Beam Catcher in the KOPIO experiment • KOPIO experiment measures KL->p0nn mode • Identification : Detect p0 and nothing 9 2g 9veto Vetoing extra particle is predominant defense to BG Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop

  3. 1. What is Beam Catcher? Beam Catcher • Photon veto which covers beam core region • under high neutron rate • ~10GHz (>10MeV) • Need to be… • efficient to g rays : 99% @ 300MeV • inefficient to neutrons : 0.3% @ 0.8GeV • Aerogel Cherenkov + distributed geometry • suppress neutron efficiency Catcher Module Lead Converter Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop

  4. 1. What is Beam Catcher? Beam Catcher – MC Event Display Event Display for g Event Display for neutron Top View Top View Side View Side View Secondary particles are created isotropically Shower spreads forward -> Can distinguish g from neutron using geometry Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop

  5. 2. Basic Design Design of Beam Catcher – Single Module • Lead converter • Size : 30 x 30 cm , 2mm thick • Aerogel • Size : 30 x 30 cm , 5 cm thick • Refractive index : n ~ 1.05 • Mirror • flat mirror • Funnel • Winston cone type • PMT • 5 inch PMT Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop

  6. 2. Basic Design Top View Design of Beam Catcher - Configuration • Tapered configuration • 10 modules (front layer) • 20 modules (back layer) • 25 layers • Number of modules • 370 modules • Coincidence condition Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop

  7. 3. Expected Performance efficiency for g efficiency g energy (GeV) Simulation – Efficiency for g • Coincidence efficiency for g vertical position dependence beam size efficiency efficient region :±7cm Y position (cm) Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop

  8. 3. Expected Performance Simulation – Insensitivity to neutrons (1) • Insensitivity to neutrons number of false veto coincidence efficiency for n efficiency neutron yield coincidence count neutron kinetic energy (GeV) →2.8 % false veto prob. Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop

  9. 3. Expected Performance single count rate by n neutron spectrum single count rate Simulation – Insensitivity to neutrons (2) • Single count rate by neutrons →single rate ~ : 600kHz / module Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop

  10. 4. Aerogel Quality Control System Aerogel Quality Control System (i) Transmittance • LED (light source) + PMT (photo detector) (ii) Cherenkov light Yield • Solenoid Spectrometer (as b source) + mirror + PMT It is important to control optical properties of aerogel Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop

  11. 4. Aerogel Quality Control System : (i) transmittance Setup for Transmittance Measurement • PMT with 2mm hole mask detects LED light • 30mm x 30mm area is scanned at 2mm interval • by moving X-Y stage Masked by black paper with a 2mmX2mm hole UV,BLUE,GREEN, YELLOW,RED 5-COLORS Aperture Aperture PMT on XY stage Aerogel on X-Y stage • position dependence of transmittance can be measured Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop

  12. 4. Aerogel Quality Control System : (i) transmittance Fit the function 1-A:Absorption CT:Rayleigh Scattering parameter Transmittance -Rayleigh scattering- Note that Rayleigh scattering is dominant in Aerogel transmittance transmittance The tile with Clean surface n=1.03 The Tile with rough surface n=1.03 A=0.93 CT=0.0088mm4 A=0.82 CT=0.0094mm4 Absorption also increase l(nm) λ(nm) Two parameters, A and CT, are used as the input to our MC simulation . Can it predict correct light yield? Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop

  13. 4. Aerogel Quality Control System : (ii) light yield Measurement of Cherenkov Light Yield To measure Cherenkov light yield… • Solenoid Magnet Spectrometer • b source + gap type solenoid magnet • Setup for light yield measurement • Spectrometer + mirror + PMT Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop

  14. 4. Aerogel Quality Control System :(ii) light yield Solenoid Magnet Spectrometer b source＋Gap-type Solenoid Magnet ==> Spectrometer • We can get monochromatic electron beam • Variable Energy up to a few MeV • Beam intensity of ~30 Hz @2.5MeV r Concept of Electron trajectory in this magnet • POINT • TWO MAGNETS • Large acceptance • High Resolution • parallel e- beam along Z-axis IRON Ru COIL Electron rotate by Bz GAP Magnetic Field is strong near the gap 0.8 m Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop

  15. 4. Aerogel Quality Control System : (ii) light yield Magnet Current VS peak e- energy Energy Energy KeV KeV 820 1460 2010 2400 2670 （ （ ） ） Resolution(%) Resolution(%) 13.7 10.1 10.1 7.5 6．3 5.7 Spec of the Spectrometer Energy spectrum of 106Ru with and without magnet ［keV］ Spectrum of focused electron ●data ▲Expectation ［A］ ［keV］ Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop

  16. 4. Aerogel Quality Control System : (ii) light yield from Spectrometer Measurement of Cherenkov Yield by the Spectrometer Setup Cherenkov image on PMT • b source 106Ru(3.541MeV) 5inchPMT MC Two trigger Scintillators are placed downstream of 10f hole at the mirror surface Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop

  17. 4. Aerogel Quality Control System : (ii) light yield Cherenkov Yield Energy Dependence Measurement1 • We measure the Cherenkov light yield with changing the energy of electron Example of the results for two aerogel samples (thickness=11mm) with similar transmittance but different refractive index n=１．０5 TR=69％@470nm P.E n=１．０３ TR=67％@470nm P.E ▲　ＧＥＡＮＴ ●　ＤＡＴＡ ▲　ＧＥＡＮＴ ●　ＤＡＴＡ Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop Incident Energy of electron Incident Energy of electron

  18. Summary Summary • Beam Catcher • Photon detector positioned in neutral beam -> Need to have enough g efficiency ->Need to insensitive to neutrons • Design • Pb + Aerogel Cherenkov counter with distributed geometry • Expected Performance • 99% @ 300MeV / 0.3% @ 800MeV -> ~3% false veto prob. • Aerogel quality control system • Transmittance • Cherenkov light yield Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop

  19. Extras Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop

  20. Beam Catcher – Prototype Test Prototype Module • Light yield – using p+ • Neutron inefficiency - using proton in place of neutrons Light Yield Proton Efficiency Data matches MC very well Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop

  21. Simulation – Insensitivity to KL (1) Coincidence efficiency for KL False veto probability by KL → ~2.3% false veto prob. Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop

  22. Simulation – Insensitivity to KL (2) Single count rate by KL → single rate : ~330 kHz Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop

  23. 4. Aerogel Quality Control System Cherenkov Yield Energy Dependence Measurement2 Example of the results for two aerogel samples (thickness=11mm) with the same refractive index but different transmittance n=1.03 TR=67%@470nm P.E n=1.03 TR=85％@470nm P.E 1.9 P.E @2.4MeV 1.5 P.E @2.4MeV ▲　ＧＥＡＮＴ ●　ＤＡＴＡ ▲　ＧＥＡＮＴ ●　ＤＡＴＡ Incident Energy of electron Incident Energy of electron A=0.82 CT=0.0094μm4 A=0.94 CT=0.0044μm4 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop

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