jianchun wang, syracuse universitydpf conference, jan 7, 19991 cleo iii rich detector and test beam...

Jianchun Wang, Syracuse University DPF conference, Jan 7, 19991

CLEO III RICH Detectorand Test Beam Results

J.C.Wangrepresenting

M.Artuso, R.Ayad, F.Azfar, E.Dambasuren, A.Efimov, S.Kopp, G.Majumder,R.Mountain, S.Schuh, T.Skwarnicki, S.Stone, G.Viehhauser, J.C.Wang, J.Wu

Syracuse University

S.Anderson, Y.Kubota, A.SmithUniversity of Minnesota

E.LipelesCalifornia Institute of Technology

T.Coan, V.Fadeyev, I.Volobouev, J.YeSouthern Methodist University


CLEO III RICH Requirement

• Cherenkov angle:

more difficult to discriminate at higher momentum

• Benchmark: 4 /K separation at 2.8 GeV/c

~2 from dE/dX ~3.5from RICH

• LiF radiator: K = 12.8 mrad => track ~ 3.8 mrad

• Multiphoton per track:

=> Design parameters:

)/()()(sin)/(1 cos 2222

21

2 pnmmn

trackC C / N

mrad

CC

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C C


The CLEO III RICH

Proximity focussing

with solid radiators.

• LiF radiators

• N2 expansion gap

• CaF2 windows

• CH4 /TEA photosensitive medium in MWPC

• Pad read-out

Photon Detector

LiF Radiator

Charged Particle

Cherenkov Photon

LiF

Radiat

ors

Photon

Detecto

rs

192 mm

CH +TEA

4

CaF Window2

Fibreglass Siderail

Reinforcing G10 Rod

Pure N

2

16 cm

101 cm82 cm

20 µm wires


LiF Radiator

• CH4+TEA photon sensitive band: 135nm - 165nm => Fluoride crystal

LiF as radiator: less chromatic dispersion

• Well polished to have better transmission

• Plane radiator region :

0.38 < |cos| < 0.82

• sawtooth radiator region: |cos| < 0.38

Sawtooth image

charged track

emerging

internally reflected radiator

photon detector

Plane image

charged track

reflected

Planar radiator

charged trackemerging

4mm

Sawtooth radiator

10 mm


LiF Radiator


RICH Photon Detector


Electronics

VA-RICH chip produced by IDE AS• 64 channels serial differential current readout

• Linear up to 3105 e input per pad

• Low noise: ENC ~ 130e + 9e C (pF) ~ 200 e

• Total 3600 VA-RICH chips used for 230,400 channels

Data board• 120 boards for final system, 8 boards for beam test

• Bias voltage and current for VA-RICH chips

• Flash ADC

• Coherent noise subtraction

9U VME crate with Vx-works


Electronics Performance

• Photon signal distribution is exponential

average signal height ~ 40,000 e

• Incoherent noise: ENC ~ 400 e

=> signal / noise ~ 100

• Coherent noise at beam test:

ENC ~ 1000 e

• In final system, coherent noise

will be ENC ~ 400 e

and subtracted on data board


• Parasitic µ beam (> 100 GeV)

• Particle rate: 100 Hz/cm2

• 2 MWPCs as track reference(x,y~0.7mm, angle~1mrad)

Radiators

Photon detectors

O-ring seal

246 cm

66 cm

Testbeam Setup

• 3 radiators (1 plane, 2 sawtooth) +

2 photon detectors

• Mounting on aluminum box resembles final scheme

• pure N2 ( < 4 ppm O2)

• For data-taking rotate in and

E866 beam dumpMWPC1 MWPC2

Triggercounters

Vetocounter

Fermilab ME beam 1.5 m

RICHconcrete


Testbeam Setup


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Sawtooth Radiator, normal incident track


Plane Radiator Resolution and N

• Data for 30° incidence angle

• Tracks chosen to have full image containment

• Photons on ring: photons with within ±3

• Background on ring: ~ 9% => N = 14.0

• From MC: Error contribution from tracking system: 2.3 mrad

C

=13.5 mr =13.5 mr <N> = 15.5<N> = 15.5 =4.5 mr =4.5 mr

mrad9.3Ctrack


Sawtooth Radiator Resolution and N

=11.8 mrad =11.8 mrad <N> = 13.5<N> = 13.5 =4.8 mrad =4.8 mrad

• Photons on ring: photons with within ±3

• track in data slightly worse than MC (4.1 mrad). Still under study

• Background on ring: ~9%

• Limited acceptance of 55%CLEO III acceptance: N = 21 => .0 mrad

C


Photon Number and Angle Resolution

Limited acceptance at all angles for sawtooth radiator

and 10° for plane radiator

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Cherenkov Angle Resolution per TrackTitle:/A/home/jwang/tex/dpf/eps/jc/plane_track.epsCreator:HIGZ Version 1.23/07Preview:This EPS picture was not savedwith a preview included in it.Comment:This EPS picture will print to aPostScript printer, but not toother types of printers.

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• MC track lower than data, may due to high backgroud at beam test,

still under study• MWPC tracking resolution at beam test is worse than CLEO III

• MC track (corrected ) is simulated with full image containment and no

error from tracking system

CLEO III inthis region


Summary

• CLEO III RICH fulfill design goals

• Status of construction:– Photon detector built 26/30, expect to finish at end of

January, and tested by the end of April– Radiator (60%), expect finish at end of April, driven

by sawtooth radiator– All VA_RICH hybrids received, nearly all tested– Designing final iteration of data board

• CLEO III RICH completion expected: June, 99

jianchun wang, syracuse universitydpf conference, jan 7, 19991 cleo iii rich detector and test beam...

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