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Test measurements of the prototype Aerogel Threshold Detector. Luka Debenjak 27 Students' Workshop on Electromagnetic Interactions Bosen, 30 . 8 .20 10. th. Introduction. - PowerPoint PPT Presentation
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Test measurements of the prototype Aerogel Threshold
Detector
Luka Debenjak
27 Students' Workshop on Electromagnetic
Interactions
Bosen, 30.8.2010
th
Čerenkov radiation arises when a charged particle in a material medium moves faster than the speed of light in that same medium:
Introduction
Vparticle > c/n
)(
1cos
n
1.05=n }
Introduction
The separation of pions from kaons requires the use of a
Čerenkov detector.
It will be placed between
scintillator walls and
shielding walls.
cMeVp
cMeVpTh
Th
K
/436
/1542
Prototype 1Geometry: d = 2 (4) cm, W x H x L = 10 cm x 20 cm x 9 (7) cm
Box with no mirrors: Box with two flat mirrors :
PMT: Hamamatsu R1828-01,
Φ = 2”
HV: -2.4kV
n: 1.07, 1.05, 1.12
Reflective coating: millipore paper
CFD: 10.9 mV
Analyses with the electrons
XY with ADC>450 ADC SUM
ADC SUM with ADC SUM with TDC cut pedestal cut
Kaos central momentum: 380MeV-530MeV, aerogel thickness d = 4 cm
eff1 = ≈ 95%
eff2 = ≈ 95%
ADC with TDC cut countsADC counts
ADC with pedestal cut countsADC counts
Efficiency and Npe
21 effeff
mmy
mmx
40
10
7
0
102
720
913
2.4/70)(
G
Ch
Ch
Ge
chfCChChN
pe
pepe
mmy
mmx
90
45
Analyses with the pions
eff1 ≈ 91% eff2 ≈ 94%
eff1 ≈ 65% eff2 ≈ 86%
p = 620 MeV/c, n = 1.07, without mirrors:
p = 480 MeV/c, n = 1.07, with mirrors:
770
938
6.3/70)(
0
pe
pepe
Ch
Ch
Ge
chfCChChN
With additional cluster cuts: Npe = 3.4
0.65
0.42
0.87 p = 1GeV/c
p = 620MeV/c
p = 480MeV/c
bg btgt
NNmax
protons
pions
Prototype 2 – single cell of the final detector
H
d
W
Lφ
PMT: Hamamatsu R877-100, Φ = 5”Nominal HV: -1.25kVn: 1.05Reflective coating: Spectraflect diffusive white reflective coating DIS: -30 mVAmplifiers: ~ x20
Geometry: d = 2 (4) cm, W x H x L = 15 cm x 35 cm x 10 cm
φ = 55 ˚
Prototype 2
d = 2 cmHV = 1250 VThr = 30 mV
eff = 90%
d = 4 cmHV = 1300 VThr = 30 mV
eff = 82%
Simulations
All the simulations are done in Litrani and SLitrani, a ROOT based program to simulate the propagation of photons through optical materials.
Photon paths and absorption points are visible.
Approximate final design
• 9 cells
• 18 Hamamatsu 5” SBA R877-100 PMTs
• Labsphere Spectraflect reflectance coating
• Aerogel thickness: 2 or 4 cm
• L = 10 cm
• H x W = 36 cm x 236 cm
• φ = 55 ˚