1. E.Kistenev History lessons Specification Primary options e-RHIC meeting at BNL, Sept 19th, 2002 Hermetic Calorimeter for e-RHIC collider experiments

2. Ions: Pmax = 100 GeV/c Protons: Pmax = 250 GeV/c Electrons: Pmax = 10 GeV/c

3. Reference: HERA Parton sideCentralCurrent side Pmax820 GeV/c38 GeV/c CalorimeterFCALBCALRCAL Depth(Labs)7.15.34 Granularity5x205x2410x20 E res(e)18% E res(h/jets)35% SolenoidInner (0.9 Lrad) Designed and built with declared goals: - full containment of all particles in the entire angular range (99.8% in the forward, 99.5% in the backward); - E/h=1; - Energy resolution (35% for jets, 18% for electrons); - 10 mrad angular resolution for jets.

4. The impact was entirely on the Jet energy resolution which converts into Q 2 reach (50%->35% -> 1.7 in Q2 range); Energy measurements for electrons is done by tracking (~2xP%), calorimeter is used to validates identification (sim. To PHENIX); There was no attempt to optimize calorimeters for photon measurements -> no interest to low-to-intermediate Pt range (opp. to PHENIX). RHIC (Heavy Ions) We expect parton structure functions modified by matter We do see early onset of quenching We are in the land of photons

6. Specification ParameterPHENIXSTAR near 4  hermeticity; -- energy and angular resolution appropriate for photon/jet measurements in the kinematic range of the experiment; -- single particle identification (implies granularity);yes? single photon measurements (implies timing resolution);yes- fast response and short memory time;yes in-situ energy calibration;yes triggering.yes

7. Implementation Parton sideCentralCurrent side Depth segmentation 233 Layer1PbWO 4 <15 L rad, PbWO 4 <12 L rad Coil0.8 Lrad Layer2PbSc accordion, 25 L rad, 18% PbSc accordion 22 L rad,8% PbSc accordion 20 L rad,12% Layer 3Tail catcher / Muon identifier (*) all depth and resolution values are subject to optimization (**) degraded resolution in cur. fragm. region is related to reduced Molier radius (***) reducing the depth of WO4 allows to save on cost without loss of the resolution, to improve granularity and to gain longitudinal segmentation

8. PbWO 4 high resolution calorimeter - 0.89 cm radiation length; - relatively low light yield; - excellent energy resolution (3%); - long integration time; - mediocre timing resolution (readout limited); - costs -base: $2/cc -> ~4x10 6 US$ -infrastructure and monitoring -> ~1x10 6 US$ -readout (~40k channels) -> ~6x10 6 US$

9. excellent uniformity; no dead areas; excellent linearity - autocompensation for light attenuation in the fibers; best possible position resolution for a given cell size; shower shape is very sensitive to impact angle - built-in pointing; simple industrialization: only one kind of scintillator tiles and only one kind of lead tiles for the whole calorimeter ATLAS(Lar) Replace Lar with scintillator and fibers PbSc Accordion medium resolution calorimeter

10. Current status - we have concept; - we designed and built 36-towers prototype; - we have R&D program which can’t be completed without building at least one more prototype; - we tested prototype in the beam at CERN, results are coming !!!!!

12. - extrude scintillator sheets (~ 50 x 350 cm2); - build reflective coating; - cut the groves; - insert fibers; - bend scintillator sheets; - cut identical size lead sheets; - bend lead sheets; - glue all of it together or use more conventional stacking method; - bundle the fibers and install readout enclosures;

13. Works as promised

14. Cost: -calorimeter ~0.5 x10 6 $US -readout (10k channels) ~1.5x10 6 $US

15. Tail catcher – how thin can it be -charged and photon components are independently measured; -neutrals carry only 30% of jet energy; -80% containment applied to 30% of energy does not change jet resolution; -etc; Bet: we’ll spend a lot of efforts optimizing it and will get 4 to 5 L abs total depth everywhere

16. Conclusions: -e-RHIC physics is challenging, it needs new approaches in detector design, -Calorimetry must be designed as a part of the whole, it should rely on delegating some part of its duties to tracking; -It will take a lot of efforts to match cost and performance but it can be done Do we actually have a chance to see eRHIC built ???