R3B Gamma Calorimeter

1
R3B Gamma Calorimeter
H. Alvarez Pol, D. Cortina, I. Durán
GENP Univ. Santiago de Compostela
H. Alvarez Pol R3B Gamma Calorimeter

NUSTAR Calorimeter WG
Valencia 17/06/05
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R3B Requirements for a Calorimeter
H. Alvarez Pol R3B Gamma Calorimeter

NUSTAR Calorimeter WG
Valencia 17/06/05
3
Experimental constrains (Kinematics)
ECM 10 MeV

• Gammas are emitted with energies up to
• Elab 3.2 ECM (for ß 0.82)
• To correct for the Lorentz boost it is
  mandatory a high granularity.
• A huge crystal length is required for full
  energy absorption

(ß 0.82)
Due to the boost, gammas are basically emitted
in the forward direction. A large open zone in
the backwards region reduces dramatically the
crystal bulk needed.
H. Alvarez Pol R3B Gamma Calorimeter

NUSTAR Calorimeter WG
Valencia 17/06/05
4
Polar angle resolution
From the relation between the lab and CM gamma
energies and assuming we know the gamma polar
angle (?) in LAB with a resolution s(?), then
s(?)
s(ECM? )
ß sin ?
1 - ß cos?
ECM?

Requesting a constant relative resolution
k1 then s(?) k1
s(ECM? )


ECM?
1 - ß cos?
ß sin ?
Most critical region ? 0.6 rad 35o
H. Alvarez Pol R3B Gamma Calorimeter

NUSTAR Calorimeter WG
Valencia 17/06/05
5
Optimum detector profile
Requesting the same energy resolution for each
crystal element, with a constant inner-face
length,
ß sin ?
r(?) cte
1 - ß cos?
H. Alvarez Pol R3B Gamma Calorimeter

NUSTAR Calorimeter WG
Valencia 17/06/05
6
Simplified detector profile

• Design parameters
• Low number of channels
• Sufficient granularity (?)
• Low radius to reduce the crystal volume
• Simplicity
• A detector divided in 3 large assemblies
• Barrel (50º lt ? lt 90º)
• Backward End Cap (90º lt ? lt 133º)
• Forward End Cap (7º lt ? lt 50º)
• The proposed segmentation results in a CM
• energy resolution of 1.5 (s) / 3.5 FWHM
• due only to polar angle uncertainties.
• Note this resolution depends on pattern rec.
  algorithms

Barrel
Backward End Cap
Forward End Cap
Backward End Cap
Barrel
Forward End Cap
H. Alvarez Pol R3B Gamma Calorimeter

NUSTAR Calorimeter WG
Valencia 17/06/05
7
A proposal for the calorimeter

• Total of 6570 crystals in 73 different crystal
  types covering the full azimuthal volume and
  polar angles between 7º and 133º
• Trapezium-like shaped
• Inner and outer faces are parallel
• Typical volume 10x20xlength mm3
• Individual crystal designs (3D and workshop
  drawings) available

H. Alvarez Pol R3B Gamma Calorimeter

NUSTAR Calorimeter WG
Valencia 17/06/05
8
A proposal for the calorimeter

• FORWARD END CAP (7º lt ? lt 50º)
• Cone-like shaped
• 32 different crystal types
• 90x32 2880 crystals
• Inner-side crystal faces dimension from 8x20 mm2
  to 25x20 mm2

• BACKWARD END CAP (90º lt ? lt 133º)
• Cone-like shaped
• 15 different crystal types
• 90x15 1350 crystals
• Inner-side crystal faces dimension from 12x20
  mm2 to 18x20 mm2

H. Alvarez Pol R3B Gamma Calorimeter

NUSTAR Calorimeter WG
Valencia 17/06/05
9
A proposal for the calorimeter

• BARREL (50º lt ? lt 90º)
• Cylinder-like shaped
• 26 different crystal types
• 90x26 2340 crystals
• Inner-side crystal faces dimension 9x20 mm2 or
  10x20 mm2

• Some final numbers (for CsI)
• Total weight 1600 Kg
• Total volume 360 dm3

H. Alvarez Pol R3B Gamma Calorimeter

NUSTAR Calorimeter WG
Valencia 17/06/05
10
Proposal setup simulation
Details on simulation on a separate talk
H. Alvarez Pol R3B Gamma Calorimeter

NUSTAR Calorimeter WG
Valencia 17/06/05
11
Summary

• A first proposal is available. Requests for
  criticism!
• Documentation available
• Technical note on the proposal R3B_CAL_01/05
• Access to the geometry datafile and other
  technical notes
• http//www.usc.es/genp/r3b

H. Alvarez Pol R3B Gamma Calorimeter

NUSTAR Calorimeter WG
Valencia 17/06/05