Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop1 Beam Catcher in the KOPIO experiment Hideki Morii (Kyoto Univ.) for the KOPIO collaborations Contents 1.What is Beam Catcher? 2.Basic Design 3.Expected Performance 4.Aerogel Quality Control System

Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop2 Beam Catcher in the KOPIO experiment KOPIO experiment measures K L   0  mode Identification : Detect   and nothing    veto 1. What is Beam Catcher? Vetoing extra particle is predominant defense to BG

Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop3 Beam Catcher Catcher Module Lead Converter 1. What is Beam Catcher? Photon veto which covers beam core region under high neutron rate –~10GHz (>10MeV) Need to be… –efficient to  rays : 300MeV –inefficient to neutrons : 0.8GeV Aerogel Cherenkov + distributed geometry –suppress neutron efficiency

Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop4 Beam Catcher – MC Event Display Event Display for  Event Display for neutron Top View Side View Secondary particles are created isotropically  Can distinguish  from neutron using geometry Shower spreads forward 1. What is Beam Catcher?

Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop5 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 2. Basic Design

Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop6 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 2. Basic Design

Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop7 Simulation – Efficiency for  Coincidence efficiency for   energy (GeV) efficiency efficiency for  Y position (cm) efficiency 3. Expected Performance vertical position dependence efficient region :±7cm beam size

Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop8 Simulation – Insensitivity to neutrons (1) efficiency neutron kinetic energy (GeV) coincidence efficiency for n Insensitivity to neutrons number of false veto neutron yield →2.8 % false veto prob. coincidence count 3. Expected Performance

Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop9 Simulation – Insensitivity to neutrons (2) Single count rate by neutrons single count rate by n neutron spectrum single count rate →single rate ~ : 600kHz / module 3. Expected Performance

Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop10 Aerogel Quality Control System (i) Transmittance –LED (light source) + PMT (photo detector) (ii) Cherenkov light Yield –Solenoid Spectrometer (as  source) + mirror + PMT It is important to control optical properties of aerogel 4. Aerogel Quality Control System

Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop11 Masked by black paper with a 2mmX2mm hole UV,BLUE,GREEN, YELLOW,RED 5-COLORS PMT with 2mm hole mask detects LED lightPMT with 2mm hole mask detects LED light 30mm x 30mm area is scanned at 2mm interval30mm x 30mm area is scanned at 2mm interval by moving X-Y stage position dependence of transmittance can be measuredposition dependence of transmittance can be measured Setup for Transmittance Measurement Aperture Aperture PMT on XY stage Aerogel on X-Y stage 4. Aerogel Quality Control System : (i) transmittance

Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop12 Transmittance -Rayleigh scattering- λ(nm) (nm) A=0.93 CT=  m 4 A=0.82 CT=  m 4 Fit the function A:Absorption CT:Rayleigh Scattering parameter 1-A:Absorption CT:Rayleigh Scattering parameter Absorption also increase The Tile with rough surface n=1.03 The tile with Clean surface n=1.03 transmittance Note that Rayleigh scattering is dominant in Aerogel Two parameters, A and CT, are used as the input to our MC simulation. Can it predict correct light yield? 4. Aerogel Quality Control System : (i) transmittance

Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop13 Measurement of Cherenkov Light Yield 4. Aerogel Quality Control System : (ii) light yield To measure Cherenkov light yield… Solenoid Magnet Spectrometer –  source + gap type solenoid magnet Setup for light yield measurement –Spectrometer + mirror + PMT

Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop14 Solenoid Magnet Spectrometer  source ＋ Gap-type Solenoid Magnet ==> Spectrometer r IRON Electron rotate by Bz COIL GAP Concept of Electron trajectory in this magnet Ru 0.8 m Magnetic Field is strong near the gap POINT TWO MAGNETS Large acceptance High Resolution parallel e- beam along Z- axis We can get monochromatic electron beam Variable Energy up to a few MeV Beam intensity of ~30 4. Aerogel Quality Control System :  (ii) light yield

Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop15 Spec of the Spectrometer Resolution(%) 1460Energy （ KeV ） 6．36．3 10.1Resolution(%) Energy （ KeV ） Spectrum of focused electron ［ keV ］ Energy spectrum of 106 Ru with and without magnet ［A］［A］［A］［A］ Magnet Current VS peak e - energy ● data ▲ Expectation ［ keV ］ 4. Aerogel Quality Control System : (ii) light yield

Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop16 from Spectrometer Measurement of Cherenkov Yield by the Spectrometer Cherenkov image on PMT  source  source Ru(3.541MeV) 106 Ru(3.541MeV) Setup MC 5inchPMT Two trigger Scintillators are placed downstream of 10f hole at the mirror surface 4. Aerogel Quality Control System : (ii) light yield

Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop17 Cherenkov Yield Energy Dependence Measurement1 ▲ ＧＥＡＮＴ ● ＤＡＴＡ ▲ ＧＥＡＮＴ ● ＤＡＴＡ n= １．０ ３ TR=67 n= １．０ 5 TR=69 We measure the Cherenkov light yield with changing the energy of electron We measure the Cherenkov light yield with changing the energy of electron Incident Energy of electron P.E P.E Example of the results for two aerogel samples (thickness=11mm) with similar transmittance but different refractive index 4. Aerogel Quality Control System : (ii) light yield

Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop18 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 300MeV / 800MeV  ~3% false veto prob. Aerogel quality control system –Transmittance –Cherenkov light yield Summary

Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop19 Extras

Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop20 Beam Catcher – Prototype Test Light yield – using  + Neutron inefficiency - using proton in place of neutrons Prototype Module Light Yield Proton Efficiency Data matches MC very well

Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop21 Simulation – Insensitivity to K L (1) Coincidence efficiency for K L False veto probability by K L → ~2.3% false veto prob.

Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop22 Simulation – Insensitivity to K L (2) → single rate : ~330 kHz Single count rate by K L

Nov Beam Catcher in KOPIO (H. Mikata Kaon mini worksyop23 Cherenkov Yield Energy Dependence Measurement2 ▲ ＧＥＡＮＴ ● ＤＡＴＡ n=1.03 TR=85 ▲ ＧＥＡＮＴ ● ＤＡＴＡ 1.5 A=0.82 CT=0.0094μm 4 A=0.94 CT=0.0044μm Incident Energy of electron P.E P.E Example of the results for two aerogel samples (thickness=11mm) with the same refractive index but different transmittance 4. Aerogel Quality Control System