a FORward CALorometer for PHENIX Richard Seto PHENIX – BNL Dec 11, 2008

Last month For the defense in AuAu (stage 1, no  /  0 ) AuAu-Ridge “new” idea (simulation – Ondrej) Ridge study in AuAu (Edouard does not like calling this ridge studies) Look at “jet” in FOCAL (eta=1-3) just look at high energy Electromagnetic shower (trigger on it?) study PID’ed particles in central arms Study particle distribution in VTX No need for  /  0 pp – Collins (simulation – Transverse task force, John L) We can reconstruct two track pi0 up to ~4-5 GeV Do transverse physics Jet, correlated with two track pi0 (Collins) extract quark transversity (using Belle data)

a couple of Decisions It is argued that Ridge not compelling enough to get funding Go with transverse physics 4 x-y (=8) strip planes

NSAC milestones Year# MileStone FOCAL? 2012DM8Determine gluon densities at low x in cold nuclei via p+ Au or d + Au collisions.Required 2013HP12 (update of HP1) Utilize polarized proton collisions at center of mass energies of 200 and 500 GeV, in combination with global QCD analyses, to determine if gluons have appreciable polarization over any range of momentum fraction between 1 and 30% of the momentum of a polarized proton. Low-x required 2014DM10 (new) Measure jet and photon production and their correlations in A≈200 ion+ion collisions at energies from medium RHIC energies to the highest achievable energies at LHC. DM10 captures efforts to measure jet correlations over a span of energies at RHIC and a new program using the CERN Large Hadron Collider and its ALICE, ATLAS and CMS detectors. Marginal without FOCAL 2015HP13 (new) Test unique QCD predictions for relation between single-transverse spin phenomena in p-p scattering and those observed in deep-inelastic lepton scattering New Milestone HP13 reflects the intense activity and theoretical breakthroughs of recent years in understanding the parton distribution functions accessed in spin asymmetries for hard-scattering reactions involving a transversely polarized proton. This leads to new experimental opportunities to test all our concepts for analyzing hard scattering with perturbative QCD. Required  G  -Jet AuAu transverse physics pA physics

Design (4 x-y planes) Silicon “pads” 4 planes of x-y “strips” (8 physical planes) Particle Direction EM0=  /  0, EM1, EM2 segments, leaves 4-5 cm no room for hadronic segment 22 X0 0.9 (originally NCC was 14 X0 +28 X0 (HAD) 1.4 ) 4 mm W old “NCC” Supertower γ/π 0 Discriminator= EM0 EM1 EM2 segments=

bulk geometry, channel count SVX4 chip count 8 layer *128 strips=1024 strips/super-tower 1024 strips/super-tower*160 super-towers/side = 163,840 strips/side 163,840 strips /(128 channels/chip)= 1280 chips/side Pads 160 supertowers/side*21 detectors/supertower= 3360 detectors/side 3360 detector*16channels/detector= pads/side readout channels (pads) 160 supe-rtowers/side *16 pads/tower*3 towers =7680 readouts/side Bricks (for EM0/EM1/EM2) 2x4:4 2x6:6 2x7:4 This edge is not in the new design

Availability History PHENIX originally bought 16 wafers (or 18?) – for VTX later with help of RIKEN we bought 1.5 extra wafers – for FOCAL Yields 454 chips per wafer the ratio between versions A and B of chip is 1:4 (VTX uses B) B is A updated 70% of chips are "good", 10% known bad, 15% probably good and 5% are probably bad Count: B: 454*1.5wafers*0.7=476 (*4/5)=380 B and 95 A available to FOCAL A from VTX: 16wafers*454*0.7*(1/5)=1016 Total possible =1491 We know that we can run both A and B versions but we never tested version A. The contentious issue is dynamic range - if it is really the same in both versions we should probably see no difference. I do not expect the answer before end of January - date when we'll probably get new strip sensor control boards available.

Strategy:staging plan NCC One side EM1+EM2 – cost ~$2M (BNL) (2012) γ / π 0 – cost $1-2M (Yonsei/RIKEN/MRI) (2013) 2 nd side $2-3M (Yonsei/RIKEN/+??) (2014?) unsure about 2 nd γ / π 0

X-view Y-view 50 GeV pi0 4-x, 2x + vertex last is overlapping 3-y, 2y last is overlapping first look at  /  0 For the  G measurement, after isolation cut, the problem was the  /  0 separation needed another factor of ~5 or so

10 Reminder – Hough Tracking All information: Vertex (assumed to be 0,0,0)‏ Hit positions (on 8 independent planes)‏ Hough Track Make slope of all hits with respect to vertex Fill Histogram Find Track Track with highest number of hits associated with it

11 Hough-Hough Tracks Find First-Track This is the best hough track of all candidates Although there is no guarantee that the x and y tracks are from the same photon. It does not matter... Black points in the histogram

12 Hough-Hough Tracks Find Second-Track Red points in histogram Remove hits close to first track Find second track by ensuring the slope (with respect to center of mass) is opposite. ignore green line

13 Results Hough-Hough tracking alone 10 GeV Photons 2 tracks not reconstructed Same track used to form inv. mass γ

14 Results Hough-Hough tracking alone 10 GeV pi0's 2 tracks not reconstructed Same track used to form inv. mass Mass correctly reconstructed π0