1 / 20

High density aerogel for ASHIPH SND – test results

10-th INTERNATIONAL CONFERENCE ON INSTRUMENTATION FOR COLLIDING BEAM PHYSICS. High density aerogel for ASHIPH SND – test results. Beloborodov K. Authors. Budker Institunte of Nuclear physics, Novosibirsk: SND team: Beloborodov K., Golubev V., Serednyakov S., Vesenev V. KEDR team:

lenore
Télécharger la présentation

High density aerogel for ASHIPH SND – test results

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 10-th INTERNATIONAL CONFERENCEON INSTRUMENTATION FOR COLLIDING BEAM PHYSICS High density aerogel for ASHIPH SND – test results Beloborodov K.

  2. Authors • Budker Institunte of Nuclear physics, Novosibirsk: • SND team: • Beloborodov K., Golubev V., Serednyakov S., Vesenev V. • KEDR team: • Barnyakov A., Barnyakov M., Bobrovnikov V., Buzykaev A., • Kononov S., Kravchenko E., Onuchin A. • Boreskov Institute of Catalysis, Novosibirsk: • Danilyuk A.

  3. Outline • VEPP-2000, SND detector • Physical program for SND at VEPP-2000 • Aerogel properties • SND aerogel counter design. Construction status. • Test with cosmic muons • Misidentification • π/K – separation power. • Conclutions

  4. VEPP-2000 complex Main parameters: •perimeter:24.4 m • collision time: 82 nsec • beam current: 0.2 A • bunch length: 3.3 cm • energy spread:0.7 MeV Luminosity: L ≃1•1032cm-2s-1at 2E= 2.0 GeV ≃1•1031cm-2s-1at 2E= 1.0 GeV ► Design feature: round beams (βx≃βz: 6.3cm) ► Project goal: 3 fb-1 till 2011

  5. Physical program for SND at VEPP-2000 • Precise measurement of the quantity R = (e+e- → hadrons) / (e+e- → +-) • Study of hadronic channels: e+e- → 2h, 3h, 4h …, h = , K,  • Study of ‘excited’ vector mesons: ’, ’’, ’, ’’, ’,.. • CVC tests: comparison of e+e- → hadrons (I=1) cross section with -decay spectra • Study of nucleon-antinucleon pair production, nucleon electromagnetic form factors, … • Hadron production in ‘radiative return’ (ISR) processes: e+e- → γγ* , γ* → hadrons • Two photon physics: e+e- → e+e- + X • Test of the QED high order processes 2 → 4,5

  6. Spherical Neutral Detector (SND) 1 – VEPP-2000 beam pipe, 2 – Tracking system, 3 – Aerogel Cherenkov counter, 4 – NaI(Tl) counters, 5 – Vacuum phototriodes, 6 – Fe absorber, 7-9 – Muon system, 10 – VEPP-2000 s.c. focusing solenoids

  7. SND drift chamber: π/K-separation Design parameters: Main parameters: • sensitive length along beam axis: 230-280 mm • internal diameters of sensitive volume: 42 mm • outer diameter of sensitive volume: 200 mm • type drift cell: JET • number of measurements within drift cell: 9 • number of drift cells: 24 • acceptance (4 layer / 9 layers): 94 % / 75 % of 4π • entrance material budget: ≤ 1 % X0 • total material budget: 4 % X0 • number of shield wires (Ø 120 μm): 984 • number of sensitive/anode wires (Ø 15-20 μm): 312 • number of cathode strips: 288 • spatial resolution: - drift time in R-φ plane: σX ≈ 150 μm - charge division along wire: σZ ≈ 1.5 mm - cathode strips: σZ ≈ 0.5 mm • angular resolution: σφ≈ 0.3 o σθ≈ 0.5 o • energy loss resolution: σ(dE/dx)/<dE/dx>≈ 25 % • π/K separation: at p ≤ 300 MeV/c

  8. μ0=10 ph.e. Dependence of the detection efficiency on particle momentum: μ0=5 ph.e. K π μ0 – average number of photoelectrons for a relativistic particle pthr – Cherenkov threshold momentum for a particle nopt 1,14 1,12 Aerogel refraction index: selection • Requierements on effective π/K - separation momentum region: • should overlap with DC: pmin = 300 MeV/c • K-mesons should not produce Cherenkov light: • pmax = 870 MeV/c • (for K-meson in e+e-  K+K-) n = 1.13 ± 0.01

  9. Aerogel: properties • Stages of dense aerogel production: • Synthesis of “light”aerogel with densityρ=0.24 г/см³ (n=1.05) • Sintering“light”aerogel to density ρ=0.50÷0.76 г/см³ (n=1.10÷1.15) Nucl.Instrum.Meth.A494:491-494,2002 Aerogel parameters: • Refraction index: n=1.13±0.01 • Density: ρ=0.65 g/cm3 • Light scattering length: Lsc=19 mm at =400 nm • Light absorbtion length: Labs=100 cm at =400 nm

  10. Aerogel counters: design 3 2 1 1 - PMT, 2 – aerogel with n=1.13, 3 - WLS Aerogel counter Design • Scheme: Aerogel + Wavelength • shifter (WLS) + PMT • (Nucl.Instrum.Meth.A315:517-520,1992) • WLS position: displaced by ~5° from • counter center • Aerogel cover: teflonwith a refractivity • of R ~98% • Aerogel thickness: ~31 mm Aerogel System Design • Cylindrical shape: R=105÷141 mm • Walls material: Al, 1 mm thickness • Consists of 3 segments with 3 separate • counters in each • Solid angle: ~60% of4π • Thickness: 0.09 Xo

  11. SND aerogel counter: construction

  12. SND aerogel counter: 27.02.2008

  13. Test with cosmic muons Time resolution Pb pμ>500 MeV/c Signal amplitude pμ>1000 MeV/c • Measurements with cosmic rays: • Signal amplitude • Inhomogeneity of light collection • Time dependence of amplitude • Time resolution

  14. Amplitude. Inhomogeneity of light collection b Map of mean amplitudes in units of photoelectrons. Boxes indicate the locations of trigger counters. The errors are statitical.

  15. Time dependence of amplitude 1 year • Barnyakov. Influence of water absorbed in aerogel on light • (poster) absorption length

  16. ACC counter time resolution • Contributions into the time resolution : • cherencov light collection time < 0.5 ns • time spread of trigger counters ~ 0.7 ns • time spread of the photon propagation in the WLS < 0.1 ns • decay time of BBQ + number of photo electrons ~ τBBQ/Nph.e.≈15/7.5≈2 ns FWHM/2.36 ≈ 2.0 ns Time resolution vs Nph.e: ΔT=τ/Nph.e. Time resolution of the counter mostly depends on decay time of BBQ τBBQ=15 ns τ = 15.7 ± 0.6 ns

  17. KEDR aerogel counter: tests with π/p-beams protons pions Nucl.Instrum.Meth.A494:424-429,2002 ─ Cherenkov light of the initial particle (π, p) ─ Cherenkov light of δ-electrons Cherenkov light of δ-electron with pe ─Cherenkov light from the teflon, scintillations, … δ-electron spectra

  18. Misidentification calculation kaons pions kaons Iπ=9.48 ph.e. kaons pions IK=0.18 ph.e. kaons • Equality of misidentifications: • Mis-n: ~1% (2.6σ) • ε(K)=90%: • Mis-n of π: ~8·10-2 % (3.3σ) • ε(π)=90%: • Mis-n of K: ~7·10-3 % (3.9σ) 1 2 2 3 pions 3 1

  19. Separation power: DC + ACC εK = 90%, Imax = 8 ph.e. επ= 90%, Imax = 8 ph.e. K meson separation π meson separation επ= 90%, Imax = 10 ph.e. εK = 90%, Imax = 10 ph.e. π meson separation K meson separation

  20. Conclusions • First time high density aerogel is used for PID • Aerogel counters designed and constructed for SND • Tests with cosmics muons was perform: • Average amplitude is around 10 ph.e. • Inhomogeneity of light collection is not more than 20% over the counter • Maximum amplitude decrease with time τ≈725 days and aerogel should be repaired time to time • Time resolution is σt~15/Nph.e • Calculation of underthreshold effects was done • Estimated π/K-separation power for SND detector

More Related