Development of FARICH-detector for the ALICE experiment at CERN A.I.Berlev, T.L.Karavicheva,...

Development of FARICH-detector for the ALICE experiment at CERN

A.I.Berlev, T.L.Karavicheva, E.V.Karpechev, Yu.V.Kupchinskiy, A.B.Kurepin, A.N.Kurepin, A.I.Maevskaya,

Yu.V.Musienko, V.I.Razin, A.I.Reshetin, D.A.FinogeevInstitute for Nuclear Research of the Russian Academy of Sciences,

Moscow, Russia

A.F.Danilyuk, V.L.KirillovBoreskov Institute of Catalysis

S.A.Kononov, E.A.Kravchenko, A.P.OnuchinBudker Institute of Nuclear Physics,

Novosibirsk, Russia

Feb.27 – March5, 2008 Development of FARICH-detector for the ALICE experiment at CERN Andrey ReshetinINSTR08, Novosibirsk, RUSSIA (slide 1) Institute for Nuclear Research, Moscow

Outline

☻ ALICE HMPID-system upgrade☻ FARICH (Focusing Aerogel RICH) concept ☻ Simulation of a multi-layer aerogel radiator

for FARICH-detector☻ Design project of FARICH-detector with MRS APDs☻ MRS APD properties (CPTA, Moscow)☻ Winston-cone holes for light-collection☻ Cooling system for MRS APD☻ Schedule for the FARICH beam test at CERN


ALICE HMPID-system upgrade

2 m

Each of 7 HMPID modules (42 windows):

- has sizes of about 1.5 x 1.0 m

- covered azimuth angle Δθ ≈ 18 degrees

Each HMPID window covers Δθ ≈ 6 degrees (solid angle ΔΩ ≈ 10 msr)

There are free modules (windows) for upgrade with Very High Momentum PID-system

Free modules (windows) for VHMPID upgrade

Ref: D.Cozza et al. (HMPID Collaboration) NIM A 502 (2003) 101-107.Feb.27 – March5, 2008 Development of FARICH-detector for the ALICE experiment at CERN Andrey ReshetinINSTR08, Novosibirsk, RUSSIA (slide 3) Institute for Nuclear Research, Moscow


ALICE HMPID-system

uses the proximity type geometry without focusing,consists of:- container with liquid C6F14 radiator (n = 1.26) and quartz window- photosensitive detector on the basis of MWPC with CsI-photocathode plane segmented into the pad readout structure

(sizes of the pad are 8 x 8.4 mm)

Rings measured during the HMPID beam test run

ALICE HMPID-system performances (Results of HMPID beam test runs at CERN):

● On an average 16 pe / ring per event track ● Single photon resolution – about 12 mrad ● Cherenkov angle resolution – about 3 mrad ● Particle identification:

π/K separation

in the momentum range from 1 to 3 GeV/c K/p separation

in the momentum range from 1.5 to 5 GeV/c


An important experimental direction of the study in physics of heavy ion collisions is the measurement of the yield of high-Pt particles. The main problem is

to study the dominant mechanism of parton energy loss in compressed nuclear matter.

“Jet quenching effect” by RHIC PHENIX Collaboration (K.Adcox et al., Phys.Rev.Lett. 88 (2002) 022301)

gives the indication on a different loss of energy by partons and gluons in nuclear matter.

Data by RHIC STAR Collaboration (C.Adler et al. Phys.Rev.Lett. 89 (2002) 202301)

show the effect of supression of high-Pt particles up to a momentum

≥ 10 GeV/c (!)


Physical requirements to characteristics of the VeryHMPID system

π/K separation in the momentum range from 3 to 10 GeV/c K/p separation in the momentum range from 5 to 14 GeV/c

INSTR08, Novosibirsk, Russia (Feb.27 – March5) (slide 5) Andrey Reshetin, INR, Moscow

CaF2 window

CsI

C4F10CF4

CaF2 window

CsI

C4F10CF4

TIC detector


FARICH detector

There are 2 options for ALICE Very-HMPID-system:

1. Focusing Aerogel RICH (FARICH) detector

and

2. Threshold Imaging Cherenkov (TIC) detector

A.Braem et al. Nucl. Instr. And Meth. A 409 (1998) 426


FARICH concept First references on this concept:

Belle group: 1. P.Krizan, Aerogel RICH, talk given at Super B Factory Workshop in Honolulu, Hawaii 19-22 January 2004, http://www.phys.hawaii.edu/superb04 2. S.Nishida, et al., Studies of a proximity focusing aerogel RICH for the Belle upgrade, Proceedings of the IEEE Nuclear Science Symposium Rome, Italy, October 17- 22, 2004. 3. T.Iijima, S.Korpar et al., Nucl. Instr. and Meth. A548 (2005) 383. 4. S.Korpar et al., Nucl. Instr. and Meth. A553 (2005) 64-69

Novosibirsk group: started discussions of the use of a multy-layer aerogel – April 2003, Alexander Danilyuk – production of 4-layered aerogel May 2004 A.Yu. Barnyakov et al., Nucl. Instr. and Meth. A553 (2005) 70.

Chargedparticle

Aerogel

n1 n2

Photon detector

The main goal of the FARICH concept is - to increase the number of photons by using thicker radiator; - to focus Cherenkov cones on the detector sensitive plane without degrading the angle resolution.

The FARICH proximity focusing type geometry was proposed. - the use of several layers of aerogel with gradually increasing refractive indices, n3 > n2 > n1 allows to focus Cherenkov cones of the same radius; - refractive indices are determined by different proximity gaps.


http://www.phys.hawaii.edu/superb04

Simulation of a multi-layer aerogel radiator for FARICH-detector

GEANT4 package was used to estimate the performance of the FARICH-detector

Input conditions and parameters for optimization of aerogel radiators:- photo-sensor array of MRS APDs with 100% geometrical efficiency;

- the measured APD photon detection efficiency (PDE, [%]) as function of the light

wavelength;

- MRS APD with/without WLS-paint on the entrance window;

- the distance between the layer No.2 and the focus plane: D = 500 mm (see Fig.)

The following aerogel parameters were considered:

● scattering length λ(sc) = 5 cm at light wavelength 400 nm;

● absorption length λ(abs) = 400 cm “ “ 400 nm;

● total radiator thickness T ≤ 50 mm;

We investigated the response of silica aerogel radiators made of 2 to 4 layers to kaons of momentum P = 10 GeV/c.Pion/kaon and kaon/proton separation power values for momenta 10 GeV/c and 14 GeV/c, respectively, have been calculated.



The simulated dependences of the

angle resolution per track σ and

number of photoelectrons N pe

on a total aerogel thickness T [mm]

are shown in Figures

Conclusion:

at total aerogel thickness up to 30-35mm

the angle resolution is almost same

for 2-, 3- and 4- aerogel layers

(difference: 10-15 %).



Radiator version

N layers T total

mmNpe r, мм

σr, 1pe,

мм

Ring area, mm2

(+/_3σ)

σ(θ), mrad

π/K sep,

σ

n=1.03 1 23.5 15 120.5 1.9 8.63E+03 0.92 4.9 2 33.1 20 121.3 1.5 6.86E+03 0.65 7.1 3 45.8 26 121.5 1.4 6.41E+03 0.53 8.7

n=1.03 with WLS 1 38.5 29 118.6 3.1 1.39E+04 1.10 4.2 2 52.6 35 120.1 2.5 1.13E+04 0.81 5.6

1 22.3 24 156.5 2.5 1.48E+04 0.91 3.9

n = 1.05 2 35.6 35 157.2 2.0 1.19E+04 0.61 5.8 3 50.0 47 157.4 1.9 1.13E+04 0.49 7.2

n=1.05 with WLS 1 40.2 49 153.6 4.1 2.37E+04 1.04 3.4

Results of the simulation for momentum 10 GeV/c

where: r is the average radius of the Cherenkov ring; σr, 1 pe is the mean deviation of the Cherenkov radius (for single photon). S is the ring area; Npe is the number of detected photoelectrons; σӨ is Cherenkov angle resolution in mrad; π/K sep is the pion/kaon separation power in number of standard deviations

for momentum 10 GeV/c.


Design project of FARICH- Prototype with MRS APDs

CONSTRUCTIONAL and

FUNCTIONAL PARTSof the FARICH PROTOTYPE

The FARICH Prototype consists of

1. Light-isolating box

2. Thin carbon entrance window for the beam

3. Radiator of Cherenkov photons (2-layer silica aerogel) on the support frame

4. Light-collecting plane with the matrix of Winston-cone holes

5. Photosensitive coordinate matrix with MRS APDs 6. Plate with LV-supply dividers and front-end electronics


Design project of FARICH-prototype with MRS APDs

MRS APD produced by CPTA

Light-collecting Cell(Winston-cone hole)

Diam. 3 mm ↓

Diam. 1.1 mm

Sensitive area: ≈ 1 mm2600 pixels

FARICH-Prototype is developing in frameworks of INTAS-CERN Research Project No. 05-103-7544:

“Development of a Cherenkov detector to extend

the PID Capability of ALICE beyond 5 GeV/c”

Proposal has been submitted to INTAS in September, 2005and this Development is the INTAS property.

We would like to thank the Belle group for very useful

test results obtained in the similar Project. (!) ↓ ↓ ↓ ↓ ↓

Belle group:

1. S.Korpar et al., Silicon photomultiplier as a position sensitive detector of cherenkov photons. “RICH2007”, Trieste, Italy, October 15-20, 2007.2. T.Iijima et al., Geiger-mode APD as a RICH Photodetector. International Workshop on New Photo-Detectors (PD07) June 28, 2007


Design project of FARICH-prototype with MRS APDs

R(max) = 165 m

m

R(min) =

133 mm

Results of simulation for 2 aerogel layers:

n1 = 1.050 ; n2 = 1.047(T1 = 17.2 mm, T2 = 17.8 mm)

K-mesons with momentum 10 GeV/c:r = 157 mm (σ = 2.0 mm for 1 pe)Protons with momentum 5 GeV/c:r = 135 mmβ = 1.0 r (limit) = 160 mmAerogel thickness (2 layers) T = 35.6 mmN(pe) = <35> pe / ring (per event track)Angle res. for K-mesons 10 GeV/c σ=0.61 mrad π/K separation 5.8 σ

Taking into account simulation results the design Geometry for the Prototype Photosensitive Matrix has been chosen:

Photosensitive ring is divided by 4 sectors: R(min)=133 mm, R(max)=165 mm, S=120 cm2Total amount of MRS APDs: 900 - on the Ring, 25 – in centreGeometrical efficiency: about 50% (APD cell sizes) and about 47% (ring sector sizes)We will have the total amount of photoelectrons: <8-9> pe / ring per event track for Prototype Matrix and <16-18> pe / ring for full scale Matrix

w

Prototype Photosensitive Matrix


MRS APD performances (CPTA, Moscow)

Measurements of MRS APD performances were carried outbyYu.Musienko on test benches at CERN APD Lab andD.Finogeev and Yu.Kupchinskiy

at INR, Moscow

As example the dependence of the photondetection efficiency PDE on a light wavelength for MRS APDs of differenttypes is shown.

We plan to use “50V-APD” for our FARICH Prototype



For tests, the entrance windows of a few

APDs was covered by a special wave

length shifter film (paint) developed by

Photonique SA (Geneva).

Dependences of the PDE on a light

wavelength for MRS “50V-APDs” and

the “50V-APDs” + WLS-paint are shown.

As result the WLS-film increases the

PDE of about two times at 450 nm

and about ten times

in the range 300-400 nm.



0.6 mrad0.9 mrad

Nevertheless the simulation results show that angle resolution for MRS APD with WLS is degraded: to 0.9 mradas compared 0.6 mrad for APD without WLS

The reason: a big dispersion of the reflective index in aerogel n = f(λ) for a blue light (?)Or a big forward scattering for a blue light (?)


Dependences of the Dark current, Gain and PDE (410 nm) on Bias [V]

for “50V - MRS APD” with WLS-paint produced by CPTA (Moscow).

For the set of 925 MRS APD we use optimal Bias in a range of

about 50-51 V

47 48 49 50 51 52 47 48 49 50 51 52 47 48 49 50 51 52


Dark current [mkA] APD Gain (x10^6) PDE (410 nm) [%]


Winston-cone holes for light-collection

Winston-cone hole:Diam. 3 mm → Diam. 1.1 mm

For testing the prototype Winston-cone holes

with parabolic inner surface in aluminium and stainless steel

plates have been produced.

Winston-holes in aluminium plate had 4 types of the treatment of an inner surface:

- treatment with special (14 class) polishing- treatment with polishing of a tool edge;- pressure method;- pressure method with polishing.

Winston-holes in stainless plate were polished by 4 different methods of electric-plasma polishing.

parab

olic in

ner su

rface


Winston-cone holes for light-collection

For APD without Winston-

cone light collection (open

version) the mean value of

amplitude spectrum is

in 120 ch.

<N> = 600 ch – for stainless

steel Winston-cone holes

Pedestal: <N(ped)> = 40 ch.

Experimental geometrical factor:

≈ 7.0 +/_ 0.36

Calculated geometrical factor:

≈ 7.44

Estimation of light collection

efficiency: ≈ 94 +/_ 5%

Relative dependence of the light collection efficiency on Winston-

cone holes of different types


Cooling system for MRS APDLay-out of the Cooling system

is presented in Fig.1

1. Copper plate

2. Heat Exchanger: Peltier module (131 W)

3. Cooler: Water radiator4. MRS APD

5. Thermo-pair sensor

The temperature Tmin = - 17 ºC

around the CPTA APD position

was achieved

Fig.1

Water micro-tubes

2

1

3

4 5


Cooling system: heat exchanger and cooler1. Heat Exchanger: Peltier Module “Drift 1.05”

Work performances:Power = 131.0 WSizes: 40×40×3.5 mmVoltage = 24.6 VCurrent = 8.6 A∆T = 70 ºC

2. Cooler a) air cooler b) water cooler

Results of CPTA APD cooling (APD coupled with copper plate ∆h = 1 mm)

0.08-17water option

0.20+8air option

1.66+22room

Dark noise [MHz]T ºC

Cooling system for MRS APD

At -17 C Dark noisecan be decreased in about 20 times(until 0.08 MHz) (!)


Schedule for the FARICH beam test at CERN

Beam channel – ALICE test beam channel T10

Beam particles – negative pions

(electrons)

Momentum range - 2 ÷ 10 GeV/c

Beam intensity -

200-500 particles/spill

Beam time –

October-November, 2008

20 shifts


Development of FARICH-detector for the ALICE experiment at CERN A.I.Berlev, T.L.Karavicheva,...

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