R 3 B Gamma Calorimeter H. Alvarez Pol – R 3 B Gamma Calorimeter NUSTAR Calorimeter WG –...
-
date post
21-Dec-2015 -
Category
Documents
-
view
216 -
download
1
Transcript of R 3 B Gamma Calorimeter H. Alvarez Pol – R 3 B Gamma Calorimeter NUSTAR Calorimeter WG –...
R3B Gamma Calorimeter
H. Alvarez Pol – R3B Gamma Calorimeter NUSTAR Calorimeter WG – Valencia 17/06/05
H. Alvarez Pol, D. Cortina, I. Durán GENP – Univ. Santiago de Compostela
Cal
R3B Requirements for a Calorimeter
Technical Proposal reference Foreseen problems / Main challenges
Total absorption efficiency Very large crystals
Gamma energy resolution Strong request on scintillator properties and
Gamma multiplicity
Gamma sum energy See problems on energy resolution
Proton energy resolution Huge dynamic range in electronics
Affordable cost !
Constrains in space (inner detector and available space)
80% (up to E=15 MeV Lab system)
2-3% E/E
(N)/<N> < 10%
(Esum)/<Esum> < 10%
<1% Ep/Ep ( Ep = 300 MeV)
H. Alvarez Pol – R3B Gamma Calorimeter NUSTAR Calorimeter WG – Valencia 17/06/05
Cal
Experimental constrains (Kinematics)
Gammas are emitted with energies up to
Elab
= 3.2 ECM
(for β = 0.82)
✗ To correct for the Lorentz boost it is
mandatory a high granularity.
✗ A huge crystal length is required for full
energy absorption
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.
ECM
= 10 MeV(β = 0.82)
H. Alvarez Pol – R3B Gamma Calorimeter NUSTAR Calorimeter WG – Valencia 17/06/05
Cal
Polar angle resolution
From the relation between the lab and CM gamma
energies and assuming we know the gamma polar
angle (θ) in LAB with a resolution σ(θ), then
= σ(θ)β sin θ
1 - β cosθ
σ(ECMγ)
ECMγ
Requesting a constant relative resolution
= k1
then
σ(θ) = k1 β sin
θ
1 - β cosθ
σ(ECMγ)
ECMγ
Most critical region: θ ~ 0.6 rad ~35o
H. Alvarez Pol – R3B Gamma Calorimeter NUSTAR Calorimeter WG – Valencia 17/06/05
Cal
Optimum detector profile
Requesting the same energy resolution for each crystal element, with a constant inner-
face length,
r(θ) = cte β sin
θ1 - β cosθ
H. Alvarez Pol – R3B Gamma Calorimeter NUSTAR Calorimeter WG – Valencia 17/06/05
Cal
Simplified detector profile
Design parameters:✗Low number of channels✗Sufficient granularity (θ)✗Low radius to reduce the crystal volume✗Simplicity
A detector divided in 3 large assemblies:✔Barrel (50º < θ < 90º)✔Backward End Cap (90º < θ < 133º)✔Forward End Cap (7º < θ < 50º)
The proposed segmentation results in a CM
energy resolution of 1.5% (σ) / 3.5% FWHM
due only to polar angle uncertainties.Note: this resolution depends on pattern rec. algorithms
Barrel
Barrel
Backward End
CapForward End
Cap
Forward End Cap
Backward
End Cap
H. Alvarez Pol – R3B Gamma Calorimeter NUSTAR Calorimeter WG – Valencia 17/06/05
Cal
A proposal for the calorimeter
H. Alvarez Pol – R3B Gamma Calorimeter NUSTAR Calorimeter WG – Valencia 17/06/05
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
Cal
A proposal for the calorimeter
H. Alvarez Pol – R3B Gamma Calorimeter NUSTAR Calorimeter WG – Valencia 17/06/05
FORWARD END CAP (7º < θ < 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 < θ < 133º)✔Cone-like shaped ✔15 different crystal types✔90x15 = 1350 crystals ✔Inner-side crystal faces dimension:
from 12x20 mm2 to 18x20 mm2
Cal
A proposal for the calorimeter
H. Alvarez Pol – R3B Gamma Calorimeter NUSTAR Calorimeter WG – Valencia 17/06/05
BARREL (50º < θ < 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
Cal
Proposal setup simulation
H. Alvarez Pol – R3B Gamma Calorimeter NUSTAR Calorimeter WG – Valencia 17/06/05
Details on simulation on a separate talk
Cal
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
Cal