especially concerning optimization of

identification power, energy resolution, efficiency, optimal readout device for

the barrel part of CALIFA,

a calorimeter to be used by

i.e. in an energy interval between the Deep Inelastic/Incomplete Fusion region

where EMRIC (CsI) operated and the Quark-gluon plasma region where ALICE/PHOS (PWO) will operate

(particle physics CsI calorimeters – BaBar and BELLE (30.3 tons of CsI)).

for Reactions with Relativistic Radioactive Beams

Bo Jakobsson , LU: R3B Collaboration meeting, GSI, April 2009

--What we learnt about CsI(Tl) as calorimeter detectors--

EXL

*) The producer should deliver polished crystals with monotonously decreasing LO. The proposal by CMS (PWO det.) to paint some parts of side areas black is not possible with CsI. It can be replaced by black scotch but even better is to lap the side areas up to the ”inflection point” This is done in 20 – 30 min / detector by the users

no loss i LO

Energy resolution (large scale production)*

- The light output (LO) non-uniformity (doping concentration) must be corrected in any finger-type CsI(Tl) detector!

10x30x100/130 mm3 two-truncated pyramide (USC) type

20x20x110 mm3

δE/E, 0.5 – 0.9%δE/E, 0.4 – 0.7 %

LO (a.u.)

TSL test with 179 MeV protons show small differences in the energy resolution between,

2 ( , )1( , , ) ( , ) a Z AL Z A E c a Z A E

The error in the determination of a2 gives some finite contribution to the resolution

TSL test with 179 MeV protons shows that response function must be controlled

Gamma source data + GEANT4 simulated response in USC type detectors

APDs are superior. PD and PMT readout is acceptable for ideal one-detector exposure but much worse when signal addition is needed?

What we learnt about gamma resolution is up to now based on ....

GEANT4 simulations of detector response [D. Di Julio, J. Cederkäll]

2. TSL proton data is now compared to simulations. First observation -When adding signals the resolution is destroyed and even new peaks appear in the spectra. This is interpreted as a result of using one unique response function.

Individual response functions are needed. Tuning of GEANT4?

• Even more important – simulation of gamma response.

500 keV gammas hitting the central detector of the 3x5 CALIFA array

What we learnt and what is still missing – readout

PDs are excellent for proton and light charged fragments but not (yet) acceptable for gammas because of too high threshold and noise level which makes signal adding particularly bad.

Some new results for the PANDA APD S8664-1010 on CALIFA detectorand ALICE/PHOS PA are

Temperature (°C)

We propose for the TUD gamma test:

- to operate at a temperature close to 0 ºC (~ +2 ºC)

-to use extra stable power supply e.g. from HVsystem@Dubna.ru providing ΔV= 0.1 V for ΔT = ±5 ºC

-to consider having extra thermal isolation between detector boxes (aerogel?)

Can the large dynamic range be handled with two readout channels – APD + PD ??

M2J MATA CO32 CAEN Vl729 for temp. and HV control

CAEN V1724 Flash ADCs

focal plane

radiator

magnet

coincidence

experiment

1 m

electronsphotons

focal plane

radiator

magnet

coincidence

experiment 64 ch MesytecCSPA

What we need now is the – gamma test at NEPTUN hopefully in September!

What is still missing – forward cap decision

LU optional forward detectorsGamma source measurements with tentative? CALIFA forward cap CsIgeometry,PANDA APD readout ALICEpreamplifiers and T +V stabilization

Compare to barrel detector performance!

The test run at The Svedberg Lab. was really successful thanks to ,

Vladimir Avdeichikov, Pavel Golubev, Douglas di Julio, Joakim Cederkäll et al., LU

Håkan Johansson, Thomas Nilsson et al. Chalmers

Martin Gascon et al,, USC

Olof Tengblad et al.,CSIC

And thank you Uppsala University for providing free beamtime!