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 ˚