from Saint Gobain studies BrilLanCe scintillating crystals Status of the art from Saint Gobain studies Perugia group 7/11/07 EMC R&D meeting

BrilLanCe Cerium-doped lanthanum bromide (LaBr3(Ce)) Good density 5.1 g/cc Excellent energy resolution 3% FWHM@E=662 KeV Scintillation light yield 65000 photons/MeV Decay time 16 ns Difficulties in growing crystals > 100cc due to fracturing during cooling because of build up of internal stress. Recently Saint Gobain >150cc, largest assembled 155cc maintain all the properties listed above: cylindrical LaBr3(Ce 5%) 51mm diameter, 76mm length (from ingots of 130mmx120mm), plan to make a detector from the full size of the ingot Energy res. 3.1% FWHM @E=662 KeV Light yield 165% of NaI with good uniformity over the length

-volumetric uniformity -crystal response to the decay of 138La Difficult growing:due to anisotropy in thermal expansion, heat transfer and mechanical strength. Comparison between small crystals and newly produced larger ones in terms of -light output -energy resolution -energy linearity -volumetric uniformity -crystal response to the decay of 138La Tested crystals Dimension (mm) shape volume quantity 4x4x5 cubic 0.08 6 4x4x15 0.24 4 4x4x30 0.48 12 13x13 cylinder 1.7 19x19 5.4 3 25x25 12.3 38x38 43.1 2 41x76 100 1 51x76 155

Light output (1 means 65000 ph/MeV) Energy resolution

Linearity: good up to 2.6MeV, after 4MeV loss of linearity but due to saturation in PMT (see small plot data taken with 3x optical attenuation).

Non uniformity studies: given ANY two points the maximum observed difference is 2.6%….

Natural Lanthanum contains 0.09% of 138La, 1.5 Bq/cc in LaBr3 Decays in 138Ba (66.4%) or 138Ce (33.6%) 1436KeV -ray + 32KeV Ba X-ray 789KeV -ray +  with endpoint 255 KeV Crystal 38x38 shielded

From Alain Iltis (Saint Gobain) LSO/LYSO price will not go down, dominatd by the cost of the material and by the manifacturing at high temperature. Limited quantity of Luthetium available -> price could grow Not less than $25/cc. - BrilLanCe material much less expensive, seems to be very interesting but hygroscopic. Price dominated by the manifacturing but can go down with the demand, now $40/cc Peak emission at 350-380nm cannot be well matched by APD’s