1. R 3 B Gamma Calorimeter H. Alvarez Pol – R 3 B Gamma Calorimeter NUSTAR Calorimeter WG – Valencia 17/06/05 H. Alvarez Pol, D. Cortina, I. Durán GENP – Univ. Santiago de Compostela Cal

2. R3B Requirements for a Calorimeter H. Alvarez Pol – R 3 B Gamma Calorimeter NUSTAR Calorimeter WG – Valencia 17/06/05 Cal

3. Experimental constrains (Kinematics) Gammas are emitted with energies up to E lab = 3.2 E CM (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. E CM = 10 MeV ( β = 0.82) H. Alvarez Pol – R 3 B Gamma Calorimeter NUSTAR Calorimeter WG – Valencia 17/06/05 Cal

4. 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 cos θ σ (E CM γ ) E CM γ Requesting a constant relative resolution = k 1 then σ(θ ) = k 1 β sin θ 1 - β cos θ σ (E CM γ ) E CM γ Most critical region: θ ~ 0.6 rad ~35 o H. Alvarez Pol – R 3 B Gamma Calorimeter NUSTAR Calorimeter WG – Valencia 17/06/05 Cal

5. Optimum detector profile Requesting the same energy resolution for each crystal element, with a constant inner- face length, r( θ ) = cte β sin θ 1 - β cos θ H. Alvarez Pol – R 3 B Gamma Calorimeter NUSTAR Calorimeter WG – Valencia 17/06/05 Cal

6. 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 H. Alvarez Pol – R 3 B Gamma Calorimeter NUSTAR Calorimeter WG – Valencia 17/06/05 Cal

7. A proposal for the calorimeter H. Alvarez Pol – R 3 B 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 mm 3 ✔ Individual crystal designs (3D and workshop drawings) available Cal

8. A proposal for the calorimeter H. Alvarez Pol – R 3 B 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 mm 2 to 25x20 mm 2 BACKWARD END CAP (90º < θ < 133º) ✔ Cone-like shaped ✔ 15 different crystal types ✔ 90x15 = 1350 crystals ✔ Inner-side crystal faces dimension: from 12x20 mm 2 to 18x20 mm 2 Cal

9. A proposal for the calorimeter H. Alvarez Pol – R 3 B 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 mm 2 or 10x20 mm 2 Some final numbers (for CsI): ✗ Total weight: ~ 1600 Kg ✗ Total volume: ~ 360 dm 3 Cal

10. Proposal setup simulation H. Alvarez Pol – R 3 B Gamma Calorimeter NUSTAR Calorimeter WG – Valencia 17/06/05 Details on simulation on a separate talk Cal

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 – R 3 B Gamma Calorimeter NUSTAR Calorimeter WG – Valencia 17/06/05 Cal