Crystals

!?

R3B/EXL meeting Milan Oct-06

Crystal growing factories

Quality and price on 20(23)*20(23)*110 mm3 detector

light output uniformity* price

AMCRYS Ltd, Kharkov, Ukraine < 2% measured 3.72 US$/cm3

St. Gobain Crystals < 5% guaranteed, < 2% measured 21.63 US$/cm3

Shanghai SICCAS High Tech. Coorperation < 2% measured 4.32 US$/cm3

SCIONIX 2.8% measured

IMP Lanzhou

*) after identical surface treatment and wrapping?

Results CsI(Tl)+Teflon+XP5300B+137Cs

•RS=5,5%±0,2 except for crystal 22x22x220: RS~7%•Global Resolution is quite constant along the Crystal•Variation from 14% to 38% of collected light along the Crystal

3000

3500

4000

4500

5000

5500

6000

6500

7000

0 20 40 60 80 100 120 140 160 180 200

Position (mm) of Gamma source along the Xtal

Co

llec

ted

Lig

ht

(ph

e-)

by

XP

5300

B

Xtal 22x22x22 teflon

Xtal 22x22x220 teflon

Xtal 44x22x200 teflon

Xtal 66x22x200 teflon

TEFLON

6,55%

6,52%

8,18%

6,68%

ResolutionFWHM Collected light for 137Cs peak

VS position of impact

Photon test facilities

Lund, MAX-lab., tagged photon beam

Energy 14 – 220 MeV, beam energy resolution 0.4 MeV at 14 MeV (from tagger system)

We will ask for ~8 MeV. How do we improve the energy tagging – shift of the two tagger planes or

insert Si detectors to measure electon energy?

VdG p + 11B gamma + ...... Etc (Madrid?)

Mainz, tagged photons -- only high energies!

Others ??

Source tests up to 3 MeV ................

The CsI(Tl) calorimeter as photon detector:

The detectors must serve as

-         EMC - multiplicity

- Σ (E)

-         Spectroscopic gamma detector (4% energy resolution at 10 MeV)

 

A lot of homogeneity tests have been performed. They all point in the same direction. We have to optimize the surface treatment, the light-guide geometry etc, to the level where it is still possible to

ask for it from the producers (or find facilities within CWG). We must use APD (or PMT) readout for E γ <

1MeV

The LU/JINR group is trying to establish a high energy photon test station. Facilities in Lund (MAX-lab and Dubna are considered but also other possibilities [VdG with (p, ) exchange reactions] are investigated (Madrid?).

For low energy irradiation a combination of various radioactive sources seems relevant .

R3B/EXL meeting Milan Oct-06

12 crystals (approx. 1 x 2 x 17 cm3)

APDs S8664-10 (Hamamatsu)

mechanical structure IPNO concept

temperature and voltage stabilisation

full simulation

electronics Saclay digitizers ??

DAQ VME/MBS

Beam-test of the Barrel concept with a

realistic prototype:

USC Barrel Prototype

Crystal type-2 Bi-frustrum shaped

Waiting for an agreement with StGobain and IMP- Lanzhou(China) --> Price drop!

Exit face fits to LAAPD S8664-2010 under negotiation

First prototypes done at Lanzhou (China

Further tests through prototype

• Good results are only achieved when there is a perfect matching between the crystal exit surface and the APD entrance area

Type 2 View of the Barrel

average dimensions

3x1x13 cm

Possible Calorimeter Design

PrototypeIn 2008, construction of a prototype of 18 Xtals [CsI(Tl)] with 9 square PMT

•Simulation and Tests of the prototype with different thickness of material in between the crystals depending on mechanical and physics considerations.

Crystal type-2 Bi-frustrum shaped

Waiting for an agreement with StGobain and IMP- Lanzhou(China) --> Price drop!

Exit face fits to LAAPD S8664-2010 under negotiation

First prototypes done at Lanzhou (China

Further tests through prototype

• Good results are only achieved when there is a perfect matching between the crystal exit surface and the APD entrance area

Type 2 View of the Barrel

average dimensions

3x1x13 cm

Dear Prof. Jakobsson,As we know (also confirmed by Prof. Gerl) LaBr3(Ce) is happend to be the best choice of crystal for building our calorimeters ---considering the experiments to be performed using these calorimeters.For R3B: <30 MeV gamma, < 300 MeV proton, huge Doppler effectsEXL: <30 MeV gamma, < 100 MeV proton, huge Doppler effectsDESPEC: <10 MeV gamma

And the challenges are:1. Required effective granularity > 10,000.2. Energy resolution 2% @ 1.3 MeV.3. Reasonable cost.

We, from India trying to address the above 3 challenges assuming LaBr3(Ce)--which is the best choice, as the crystal for our all the 3 calorimeters. Now to address the above issues, we're making an MoU with Saint-Gobain Crystals --a joint venture of Indian research institutes/industries and Saint-Gobain Crystals, BANGALORE. In this joint venture, R & D related to "LaBr3(Ce) yield improvement" (which is required to bring down the cost of the final product--- apart from detector fabrication expenses) & others (like required "timing resolution" which depends on Ce concentration) will be jointly addressed by Indian research institutes and Saint-Gobain at their Bangalore facility (a medium capacity LaBr3 growth facility will be established in Bangalore by India-Saint Gobain joint venture with cost sharing basis. Saint-Gobain does not have any LaBr3 growth facility at Bangalore presently. They grow only CdWO4 here). The research output will be fed to their France unit for mass production. The grown cyrstals will then be brought to Bangalore for finishing, integration...making detector etc. where Indian industries will participate.

A summary on the proposal from U.K. Lal, BARC, India(text directly from E-mail)

Here all the Indian services and R & D efforts provided to Saint-Gobain will be free of cost ---will not be taken into account to estimate the final cost of the product.Hence the final cost will be very low ---which is NOT possible for Saint-Gobain without utilising Bangalore facility and Indian expertise and services !

And finally using those detectors all the THREE calorimeters will be builtat BARC which has got an excellent design and manufacture centre comaparable to any national lab in the world.

Now, coming to design studies of this crystal --we've just started workingwith LITRANI --according to Prof. Gerl's suggestion since last Oct./Nov.about which I wrote you yesterday also. We want to study all the test experiments for LaBr3(Ce) (light collection with PMT/APD/... collection surface geometry .... what the Spanish group is doing for CsI(Tl). This is just our beginning. We've NOT attended any CWG-meeting held so far. Hopefully, in the next meeting I'll present our studies for this crystal (supposed to be the actual crystal for our calorimeters !)

This is our message from Trombay group from India (to the CWG-Lundmeeting), for solving the challenges with the right crystal.

Sincerely,Dr.U.K. Pal, NPD, BARC

Conclusions (Milano, Oct. 06)

1. Collected light through long crystals is not constant. Tests with non collimated 137Cs source give resolutions greater that 15%.

2. The choice of VM2000 seems obvious3. With XP1912, it seems difficult to have a resolution

better than 9%-10% at 662keV on long crystals because:a. Area covered by PMT is only 36% with 22x22

output faceb. Intrinsic resolution of crystal is quite high

(~4/5%)c. Photocathode is not green extended bialkaly

4. Resolution obtained with PMT XP1912 and APD are quite comparable until 3.25MeV

5. No work has been done on surface quality (polished/rough)

6. Use of XP1452 seems promising7. Tests on LaCl3 crystal

”New conclusions”

1. Collected light through long crystals is not constant. Tests with non collimated 137Cs source give resolutions greater that 15%. Can be handled – but to which extent by producer?

2. The choice of VM2000 seems obvious. Confirmed!3. With XP1912, it seems difficult to have a resolution

better than 9%-10% at 662keV on long crystals because:a. Area covered by PMT is only 36% with 22x22

output faceb. Intrinsic resolution of crystal is quite high (~4/5%)

<2%c. Photocathode is not green extended bialkaly ?Can be improved – also with APD (+PD?)

4. Resolution obtained with PMT XP1912 and APD are quite comparable until 3.25MeV APD (stabilisation!)

5. No work has been done on surface quality (polished/rough)

A lot of this kind of work has been done now6. Use of XP1452 seems promising or APD?7. Tests on LaCl3 crystal Promising but cost is high and

development time long.8.................