Claudia Höhne CBM collaboration meeting Dubna, October 20081 RICH workgroup program TimeNameTitle...

1 Claudia Höhne CBM collaboration meeting Dubna, October 2008

RICH workgroup program

Time Name Title

9:00 Claudia Höhne (GSI) Status report RICH R&D:- RICH MAPMT tests at GSI/ FEE- RICH design (PNPI)- mirror R&D (HSE)- RICH prototype (Pusan)

9:30 Elena Belolaptikova RICH layout simulations

9:50 Vladimir Rykalin (IHEP) PMT and WLS activities at IHEP

10:10 Piotr Koczon (GSI) WLS film studies

10:40 all discussion

11:00 COFFEE

Wednesday, October 15, 2008:


Electron identification

Time Name Title

11:00 COFFEE

11:30 Simeon Lebedev (GSI/JINR)

Electron identification in RICH and TRD

12:00 Tatiana Akishina (JINR) Energy loss studies of electrons in the TRD

12:15 Olga Denisova (JINR) Systematic studies of e/ identification in TRD

12:30 LUNCH


Status RICH R&D

• layout and design E. Vznuzdaev, O. Tarasenkova, E. Belolaptikova, S. Lebedev

• mirror M. Dürr

• Photodetector S. Bianco, P. Koczon, CH

• WLS film studies

• FEE

• test setup at GSI

• activities at IHEP Protvino V. Rykalin

• prototype I.-K. Yoo, J. Yi, et al.


RICH design

Visit of Evgeny Vznuzdaev and Olga Tarasenkova (PNPI, St. Petersburg) at GSI, April 2008

• discussion on RICH design

• so far dimensions are still subject of layout optimization

• only range can be given (compact to standard RICH dimensions)

• discussions on integration of RICH an MuCh in CBM Cave

• mirror layout and support discussed in some more detail

• current schedule:Preproduction design and prototyping: 2009 - 2010Production : 2011 - 2015Assembling and testing : 2014 - 2015


RICH mirror design

• "mirror and support are one thing" (!)

• important consideration: mirror tiles of hexagon or rectangular shape?

• mirror material: glass, carbon, beryllium ?

• mirror support structure – depends on shape of mirror tiles

hexagon tiles:one mount in center of mirroradjustment around 2 axis

rectangular tiles:typically 3 adjustable mountsalso shift along z-axis possible

or or ...


Hexagonal mirror tiles

Hexagon effects:

• Lack of exact geometrical description; impossible to divide a spherical surface into hexagons exactly ; one can only to approximate (manually?) the surface by hexagons with irregular gaps between them (0.5-12mm); • Cutting of hexagons to fit a line between 2 mirrors and to fit (if necessary) other sides of the surface different size of hexagons.

E. Vznuzdaev, PNPI St. Petersburg


Rectangular mirror tiles

Latitude/longitude division:

• The globe-wise division has a precise geometrical description; • Minimal gaps between units, only technological gaps;• Only 2 variants of unit dimensions;• No fitting cuts for units



RICH mirror design considerations

Detector Rc Division S/mirror S/unit Mirror Rad. [m] layout [m2] [m2] substrate

thickness----------------------------------------------------------------------------------------------------Hermes 2.2 2x4 (T*) 1.6 0.8x0.25 CFC 0.01LHCb(1) 2.7 1x4 (T*) 1.9 0.8x0.6 Be 0.007CBM 3.0 ? 5.9 ? ? ?PHENIX 4.0 2x12(T*) 10.0 0.8x0.5 CFC 0.004----------------------------------------------------------------------------------------------------Compass 6.6 58(H*) 10.5 0.18(0.5**) Glass 0.06LHCb(2) 8.6 21(H*) 4.1 0.17(0.5**) Glass 0.05

* T – trapezoid, H – hexagon ** diameter of circumscribed circle




Common consideration (hexagonal shape):

The geometrical relation between linear dimension of mirror unit d and radius of curvature Rc for Compass/LHCb2 case: K=d/RC=0.5/7.5 = 0.067 (soccer ball has K~0.75).

Let us take the same K for CBM case. Then:d=(Rc)xK=3.0x0.067=0.2m,

and number of hexagon units is 84 for square of 5.9m2, what significantly increases amount of substance for mirror support(radiation thickness). Also we should increase correspondingly the number of tuning elements for mirror unit and time for their assembling and adjustment . All above brings to increasing of the cost for the mirror supportalso.





thickness----------------------------------------------------------------------------------------------------Hermes 2.2 2x4 (T*) 1.6 0.8x0.25 CFC 0.01LHCb(1) 2.7 1x4 (T*) 1.9 0.8x0.6 Be 0.007CBM 3.0 84(H*) 5.9 0.07(0.2**) Glass 0.05PHENIX 4.0 2x12(T*) 10.0 0.8x0.5 CFC 0.004----------------------------------------------------------------------------------------------------Compass 6.6 58(H*) 10.5 0.18(0.5**) Glass 0.06LHCb(2) 8.6 21(H*) 4.1 0.17(0.5**) Glass 0.05






thickness----------------------------------------------------------------------------------------------------Hermes 2.2 2x4 (T*) 1.6 0.8x0.25 CFC 0.01LHCb(1) 2.7 1x4 (T*) 1.9 0.8x0.6 Be 0.007CBM 3.0 3x10(T*) 5.9 0.43x0.46 Glass 0.05PHENIX 4.0 2x12(T*) 10.0 0.8x0.5 CFC 0.004----------------------------------------------------------------------------------------------------Compass 6.6 58(H*) 10.5 0.18(0.5**) Glass 0.06LHCb(2) 8.6 21(H*) 4.1 0.17(0.5**) Glass 0.05




RICH mirror R&D

• February 2008: first mirror prototypes tested (FLABEG, 6mm thickness, 3.2m radius Al+MgF2 reflective coating)

• good reflectivity (75% at 180nm)• however: surface irregularities on cm scale

• nevertheless: one sample shipped to Pusan (Korea) for new RICH prototype

• discussions with FLABEG, but 2nd mirror sample of FLABEG had basically same deficciency

• contact to Compass company (Czech), waiting for new prototype (supplier of RICH2 mirrors of LHCb)

M. Dürr, HS Esslingen


Mirror mount


• mirror mount for rectangular mirrors:

• to be tested as soon as possible together with new mirror prototypes

• test bench available at PNPI


Open Questions

• mirror material – glass, carbon beryllium??? material of mirror mount – aluminum, carbon structures, ... ???

• which material budget can we allow for while still having highly efficient global tracking capabilities?

• mirror radius?

• RICH layout, size?

• can we stay with direct reflection to photodetector plane and resulting high ring densities with smaller radius?

• sufficient surface regularity with small mirror radii? (what is sufficient?)

simulations and work of E. Belolaptikova, S. Lebedevsimulations to be done,

test in RICH prototype

(Selection of open questions:)


RICH layout studies

RICH layout studies by Elena Belolaptikova (GSI summer student):

• systematic studies on RICH material budget (standard RICH), in particular concerning the RICH mirror and its effect on global tracking

• glass mirror of 3mm, 6mm, 10mm thickness

• aluminum support structure from aluminum rods included:

• radius 3 cm, 5mm wall thicknes

• radius 1.5 cm, 2 mm wall thickness (proposal of E. Vznuzdaev, industry standard)

• layout optimization of compact RICH detector

Systematic investigation and improvement of ring finder in high ring density environment, Simeon Lebedev (GSI/JINR)

• ring finding and electron identification for standard & compact RICH scenario


Photodetector R&D (GSI)

GSI activities on photodetector FEE, single photon test setup(Simone Bianco (summer student), Piotr Koczon, C.H.)

• wavelengthshifter (WLS) film studies in cooperation with CERN *

• development of FEE based on n-XYTER for MAPMT (Hamamatsu, H8500)

• development of test setup for single photon measurements at GSI

• pulse height distributions of single photons

• crosstalk effects with and w/o WLS films

* cooperation and help by A. Braem, M. van Stenis, C. Joram


Quarz

testbeam:protons, p=3.5 GeV/c

H8500

Hamamatsu H8500

sin = n sin(-) → for = 20° is = 37.7°

for Quartz thickness of 1cm and R=5cm: L = 3.16 cm, R = 1.15 cm

RR

L

~6 cm

~6

cm

tilting needed because otherwise light would be internally reflected in quartz

to check: when does intenal reflection set in again

Photodetector test during CBM testbeam Sep'08 ?• plan was: participate with photodetector test, use Cherenkov light generated by protons (p = 3.5 GeV/c (2.3 GeV/c)) in plexiglas:


Simulations - testsetup

setup in CbmRootsimulations:

• best tilting angle of plexiglas 45°

• appr. 50 photons/ event (plexiglass of 8 mm thickness)

appr. MAPMT image

S. Bianco, CH, GSI


n-XYTER readout for H8500

• use n-XYTER chip for readout of H8500

• problem: typical gain of H8500 1-2∙106 but dynamical range of n-XYTER 120000 e-

• need attenuator of appr. factor 20-50

→ prepare PCB boardn-XYTER FEB

designed as general pupose board

atte

nuat

or

PC

B b

oard

S. Bianco, CH, GSI


CBMRICHAB01

PMT N-XYTER

R1 R2 C1 C2

0 10 k 1 nF 10 pF

91 10 0 nF 2 pF

0 100 1 nF 10 pF

91 10 0 nF 10 pF

0 100 500 pF 10 pF

0 0 0 F 0 F

• PCB board produced, several R-C combinations tested with test pulse

• ongoing discussions with detector lab

S. Bianco, CH, GSI


Test of CBMRICHAB01

• input (pulse generator): 2 V, 10 ns

• R2 = 100 , C1 = 1 nF, C2 = 10 pF

• R1 = 91 , R2 = 10 , C1 = 0 nF, C2 = 10 pF

0.04 V

15 ns

test with n-XYTER

S. Bianco, P. Koczon, GSI


.... n-XYTER FEB missing

• test setup was ready for the beam, however an n-XYTER FEB was missing (only 3 became available – 2 for the silicon strips, 1 for the GEM)

S. Bianco, CH, GSI


Next steps

• more n-XYTER FEBs will become available in the near future, one existing (Rev B) can be shared already now with the silicon strip R&D group (J. Heuser)

• develop and understand n-XYTER readout of H8500

• consider separate future version of CBM-XYTER specifically for H8500

• investigate characteristics of H8500

• single photon response, homogenuity across the surface and single pixels

• crosstalk effects w and w/o WLS coverage

• use MAPMT test setup for next CBM testbeam in February/ March 2009

• provide readout to group of i.K. Yoo, Pusan University, Korea


RICH prototype

• development of RICH prototype at Pusan University, Korea (I.K. Yoo JunGyu Ji, et al.)

• first small scale prototype already investigated

• 2nd full scale prototype to be build autumn/ winter 2008

• test various radiator gases/ mixtures

• combine parts developed elsewhere:

• implement first mirror prototype (FLABEG, 20 cm x 20 cm)

• once available: use n-XYTER for readout

• test: electron beam at TEST LINAC, PAL (Pohang Accelerator Lab.), Korea. ; (pe ≈ 60MeV/c)

• problem: very wide beam spot, poor beam quality

→ implement beam diagnostics, collimators!


RICH prototype

mount for 4 H8500

MAPMTs

extension vessel

vessel_front window

mirror:R = 2700 or

3200 mm

side door

J. Yi, I.K. Yoo, Pusan University, Korea


Photodetector "plane" in prototypeJ. Yi, I.K. Yoo, Pusan University, Korea

ring on 4 MAPMTs


Mount for 4 MAPMTs

Mount_0

4PMTs

Mount_1

Bolt



Gas system

Molecular Sieve

•T : 25C•P :±20mbar•H : ~ 23%RH 3196 ppm

P : 3 atm

P : 3 atm

P : ~1 atm



Summary: RICH prototype

• gas vessel under production in Pusan

• develop beam setup which allows to work with the existing poor beam quality

• n-XYTER readout to be investigated/ developed at GSI

• 1st mirror prototype delivered by HSE

• future prototypes will be combined and tested with mirror mount


Discussion

• layout and design studies

• mechanical concepts developed at PNPI, details on RICH size and mirror layout missing for further progress

• detailed (promising!) simulations on RICH material budget (mirror and mount), RICH layout, e-ID in high ring density environment

• mirror R&D

• 1st prototype shipped to Pusan for RICH prototype

• new prototypes expected soon, if promising combine with mount

• photodetector R&D

• promising WLS film studies (crosstalk with MAPMT?)

• FEE under way (plan use of n-XYTER FEB)

• test setup at GSI under development

• prototype under construction at Pusan university

• important: get beam quality under control!

Claudia Höhne CBM collaboration meeting Dubna, October 20081 RICH workgroup program TimeNameTitle...

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