B. Jakobsson, CWG meeting, June 18-19, 2007: Intoductory slide

 -----------------------------------------------------------------------------------------------------------------------------------------------------Requirements: identification energy resolution granularity ---------------------------------------------------------------------------------------------------------------------------------- R3B p ( 50 - 300 MeV) E/E ≤ 1% Optimized with respect to the ( 0.01 - 15 MeV) E/E 3-5% Si-setup which defines the EXL p ( - 200 MeV) E/E < 1% angular resolution ( 0.2 mrad). ( 0.01 - 10 MeV) E/E < 3% The cost is a limiting factor! --------------------------------------------------------------------------------------------------------------------------------- 

“The biggest challenge for the calorimeters are to make them optimal for both protons and photons in a very large dynamic range”!

The dynamic range is enormous, 10 keV – 200 MeV (cf 150 keV – 5 MeV for DSSD) [CWG] double readout (PD+APD)? [FEE group] several amplifications on ASIC?

 Alternative materials to CsI(Tl) have been considered but so far regarded as “exclusive”.

[CWG] define realistic alternatives for Demonstrators and/or for the final calorimeter {presentations by Peyré, Nilsson/Tengblad and proposal by U.K.Pal, BARC}

Detector geometry for Demonstrators should be fixed and realistic calorimeters simulated. [R3B/EXL] should agree on one or two Demonstrators. [Simulation group] ready to simulate an EXL version?

 In-beam tests are necessary after a lot of investigations on light collection and homogeneity with radioactive sources{Peyré,Cortina}. ~200 MeV protons from TSL (established) {Avdeichikov} and KVI

.[CWG] from where do we get 300 MeV protons and > 1 MeV photons {Isaksson}?

Proton test facilities

Uppsala, TSL, GWC, B-line (Blue hall):

Energy 179.31±0.80 MeV. Flux reduced from normal 2·108 s-1 to 900 s-1 with a profile as registered from DSSD triggers in the figure below,

Groningen, KVI, AGOR Max energy 190 MeV, low flux line can be developed.

GSI, SIS , 300 MeV in parasitic mode?

[ strip unit 4 mm]

The CsI(Tl) calorimeter as proton detector:

The range of a 200/300 MeV proton is 10.0/19.6 cm and the mean-free-path for a 300 MeV proton is ~ 44 cm, so why worry about the detector length and geometry?

Because several contributions to the energy resolution are affected by length and geometry

-         inelastic scattering: 200/300 MeV gives 25/55 % losses, geometry has little importance

-         elastic scattering, partly corrected by adding neighbouring detector signals, geometry important.

-         sliding trajectories, depend on geometry and lateral straggling

-         longitudinal straggling: ~EP, geometry has little importance,

-         efficiency of light colllection, geometry and surface treatment important

-         homogeneity of light collection, geometry rather unimportant, surface treatment crucial

An extensive discussion of these phenomena in the talk of V. Avdeichikov

The light-energy response is an additional source of error in the energy. Can a unique relation be used for all detectors? - combined with laser or alpha source control of absolute level? – or must individual response functions be used?

The (noise)contributions to the energy dispersion from accelerators, electronics etc are possibly smaller than expected (see result from TSL test with DSmacroStripD + 3*3 CsI(Tl), 20*20 *110(210) mm3)

effects on the 1% level, like temperature stability, should be carefully considered

Next step in the LU/JINR work is to “calibrate” GEANT4 based simulations at 180 MeV and with the exact prototype geometry. Then extrapolate simulations to 300 MeV and propose geometry accordingly.

DSSD

PDs (CHICSi)

APDs (ALICE, Zelenograd)

210 mm CsI(Tl)detectors

110 mm

DSSD (LYCCA)

Lund DSSD-CsI prototype for proton tests

Energy spectrum obtained in central CsI by the Lund TSL setup,May 2007

σE/E < 1% for the direct beam peak, that contains detector + beam dispersion

Proton energy resolution

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 .