R 3 B Gamma Calorimeter

1. Cal 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

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

3. Cal Experimental constrains (Kinematics) ECM = 10 MeV 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 (β = 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. 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) σ(ECMγ) β sin θ 1 - β cosθ ECMγ Requesting a constant relative resolution = k1 then σ(θ) = k1 σ(ECMγ) ECMγ 1 - β cosθ β sin θ Most critical region: θ ~ 0.6 rad ~35o H. Alvarez Pol – R3B Gamma Calorimeter NUSTAR Calorimeter WG – Valencia 17/06/05

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

6. 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 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. Cal 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. Cal A proposal for the calorimeter 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 H. Alvarez Pol – R3B Gamma Calorimeter NUSTAR Calorimeter WG – Valencia 17/06/05

9. Cal A proposal for the calorimeter 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 H. Alvarez Pol – R3B Gamma Calorimeter NUSTAR Calorimeter WG – Valencia 17/06/05

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

11. 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