Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview Implementation and performance analyses of the aerogel Cherenkov counter for the Kaos spectrometer Dr. Luka Debenjak University of Ljubljana & Institute for nuclear physics, Mainz, Germany April 5, 2013 L. Debenjak Implementation and performance analyses of the Cherenkov counter
Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview Introduction 1 A1 experimental hall The K AOS spectrometer Scintillating fiber detector prototype Aerogel Cherenkov counter 2 Threshold Cherenkov counters The detector design Simulations in SLitrani 3 Data analysis and results 4 Calibration Test with cosmic rays Test with protons and positrons Test with protons and pions Test with kaons Overview 5 L. Debenjak Implementation and performance analyses of the Cherenkov counter
Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview With the upgrade of the electron accelerator MAMI at the Institute for nuclear physics in Mainz, Germany, the investigation of strangeness physics is possible: study of YN and YY interactions ( E max = 1 . 6 GeV). In electro-production of strangeness a proton/neutron is replaced by a hyperon. → e ′ + K + + Λ e + p − 2.5 2 (GeV/c) E98-108 + K 2 2 Four-Momentum Transfer Q e’ y x θ e θ K 1.5 p + z θ Λ γ * K Λ e K Σ φ 1 π N N ρ Λ ω N scattering plane MAMI-C E93-018 reaction plane 0.5 η N MAMI-B E94-107 E05-115 0 Quark-level process of kaon electro-production 1 1.2 1.4 1.6 1.8 2 2.2 Invariant Energy W (GeV) inside nucleus: Q 2 = − q µ q µ W = √ s γ u s u s d d u u L. Debenjak Implementation and performance analyses of the Cherenkov counter
Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview A1 experimental hall The A1 three spectrometer facility at MAMI: Two additional magnetic dipoles are installed upstream of the target to compensate the deflection. This enables measurements to be performed at 0 ◦ kaon scattering angle. Electrons Hadrons Pre-target The spectrometers are labeled as A (red), B beam chicane Beam line (blue) and C (green) with K AOS spectrometer in the middle (violet). L. Debenjak Implementation and performance analyses of the Cherenkov counter
Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview The KAOS spectrometer Detection of kaons is effective only in K AOS (short trajectory length & large momentum): Configuration single dipole 0.5 Max. momentum 2100 MeV/c Kaon survival probability Momentum acceptance (∆ p / p ) 50 % Kaos Solid angle acceptance 10.4 msrad 0.4 10 − 3 Momentum resolution ( δ p / p ) Length of central trajectory 5.3 m 0.3 detector package: 0.2 C A B Hadron arm: multi-wire proportional chambers, scintillator walls and aerogel Cherenkov counter 0.1 Electron arm: scintillating fibers 0 200 300 400 500 600 700 800 900 1000 1100 1200 Kaon momentum (MeV/c) Collimator Magnetic dipole ToF walls MWPCs Electron arm Hydraulic cylinders L. Debenjak Implementation and performance analyses of the Cherenkov counter
Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview Scintillating fiber detector prototype Electron trajectories are measured by two planes of scintillating fibers: L. Debenjak Implementation and performance analyses of the Cherenkov counter
Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview Scintillating fiber detector prototype Simulations done in Litrani . One bundle of scintillating fibers: Relative number of detected photons with illuminated fiber corresponding to MaPMT ch. One of the issues: NA = sin α = 0 . 71 Nr. 16 (experiment vs. simulation): L. Debenjak Implementation and performance analyses of the Cherenkov counter
Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview Threshold Cherenkov counters The separation of rare kaons from the abundant pions requires the use of a Cherenkov detector. 1 0.8 0.6 N/N max Condition for Cherenkov radiation: 0.4 v particle > c 0 / n 1 c 0 cos θ C = β n ( ω ) = 0.2 vn ( ω ) kaons pions 0 0 500 1000 1500 2000 2500 3000 Particle momentum [MeV/c] p K + ≈ 1470 MeV/c n = 1 . 055 ⇒ th p π + ≈ 415 MeV/c th radiator: silica aerogel L. Debenjak Implementation and performance analyses of the Cherenkov counter
Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview The detector design 270 aerogel tiles: Novosibirsk (Boreskov Inst. Catalysis/Budker Inst. Nucl. Phys.)- d = 2 cm hole thin wire hole + Matsushita Electric Works Ltd. aerogel - d =1 cm φ = 1 mm φ = 1 mm knot M3 screw 12 Hamamatsu 127 mm (5”) PMTs: 10 x R1250 + aerogel aerogel 2 x SBA R877-100: QE max = 35% side bar side bar 5 L Labsphere Spectra�lect re�lectance coating; re�lectivity: 95-98% from 300 to 1200 nm Aluminized mylar foil W = 150 cm 6 segments 50 100 45 40 80 quantum efficiency [%] 35 aluminised mylar foil 60 30 mylar foil R [%] mirror 25 40 o f = 35 20 H = 45 cm 15 20 10 0 5 200 300 400 500 600 700 800 wavelength [nm] 0 200 250 300 350 400 450 500 550 600 650 700 wavelength [nm] L. Debenjak Implementation and performance analyses of the Cherenkov counter
Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview The detector design L. Debenjak Implementation and performance analyses of the Cherenkov counter
Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview Simulated total number of photo-electrons vs. aerogel thickness: Different types of diffusive box in a single segment: SBA R877-100 12 R1250 10 8 N pe 6 4 2 Number of p.e. at different angles between the 0 0 1 2 3 4 5 6 7 8 9 mirrors: d [cm] Simulated distribution of p.e. for positrons and pions at 720 MeV/c momentum: 12 mylar foil p = 720 MeV/c, d = 3 cm white reflectance coating 10 400 pions pions χ χ 2 2 / ndf / ndf 35.73 / 14 35.73 / 14 350 e + ± ± 8 p0 p0 2037 2037 45.2 45.2 ± ± p1 p1 4.272 4.272 0.053 0.053 π + 300 positrons positrons N pe 6 χ χ 2 2 250 / ndf / ndf 54.87 / 18 54.87 / 18 p0 p0 ± ± Counts 2011 2011 44.8 44.8 p1 p1 ± ± 6.759 6.759 0.071 0.071 200 4 150 2 100 50 0 0 0.25 0.5 0.75 1 x/a 0 0 5 10 15 20 25 30 N pe L. Debenjak Implementation and performance analyses of the Cherenkov counter
Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview Transitions, reflections and absorptions of photons inside AC: Spectrum of photons reaching the Transition from material to material Reflection inside material by material photocathode surface. Wavelength of p hotons seen Generated wavelength for Čerenkov photons Entries 33491 Entries 33491 Mean Mean 465 nm 465 800 10 3 × 14000 35000 700 250 30000 12000 600 200 25000 20000 500 150 10000 15000 Counts Counts 100 400 8000 10000 50 5000 300 6000 0 0 Cathode Cathode Matsushita 200 Matsushita Sodocal Sodocal BIC/BNP 4000 BIC/BNP Air Air Air Air BIC/BNP 100 BIC/BNP Sodocal Sodocal Cathode Matsushita Cathode Matsushita 2000 0 250 300 350 400 450 500 550 600 650 700 250 300 350 400 450 500 550 600 650 700 Absorption by wrapping when coming from material Reflection by wrapping when coming from material λ [nm] λ [nm] 10 3 10 3 × × 120 700 600 100 500 80 400 60 300 40 200 20 100 0 0 Cathode White coating Sodocal Reflective Cathode Air White foil Sodocal coating Air BIC/BNP aerogel Reflective Wrap PM BIC/BNP aerogel foil Matsushita aerogel Wrap PM Matsushita aerogel L. Debenjak Implementation and performance analyses of the Cherenkov counter
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