Forward hard  measurement by a W/Si calorimeter Y. Kwon, J. H. Kang, M. G. Song (Yonsei Univ.) 1

 4 presentations will be made in sequel… One presentation must be made (pressure from convener ), and it is impossible to prepare one short presentation understood by a general public.  4 presentations will be Generals & response to signal ( 1 st ), Background ( 2 nd ), Embedding and signal extraction ( 3 rd ), and (Beam test) data presentation ( 4 th ).  Next step will be to report contribution to ALICE and competitiveness to CMS/ATLAS counter parts. Presentation schedule 2

General operation SEG0SEG1 SEG2 y z PADSTRIPW Each tungsten layer : ~1 radiation length. R M ~ 1.5 cm e  3

Schematics (y-z view) SEG0SEG1 SEG2 y z PADSTRIPW 1.5 cm Pad y-index = 0 Pad y-index = 1 Pad y-index = 55 4

Schematics (y-z view) The whole detector is covered by 4x4 tile ( or 6 cm x 6 cm ) sensors. Each pixel in the left plot corresponds to a pad. 5

PHENIX FOCAL Beam test

Detector layout SEG2SEG1 SEG0 Preamp crate 7

Readout configuration Preamp hybrid 7 vertical channels grouped (cost issue) 8 pad sensors in one carrier board 8

Carrier board & packaged sensor Carrier board & packaged sensor 9 Somewhat old board to house 4 sensors instead of 8. Sorry for being lazy! Back side Front side

Sensor on a wafer 6 cm x6 cm cm x1.5 cm

 Electro-Magnetic components , e + /e - (  + /  - ? … not a big deal )  Hadronic components  + /  -, p, n, p, n, K + /K - /K L, … 11 Response to signal _

Characteristic response to EM signal e’s at  =2, p T =10 (GeV/c),  =0.174 Characteristic response to EM signal e’s at  =2, p T =10 (GeV/c),  = Energy deposition within a few pads Look at log scale! Rapid drop in energy deposition between SEG1 & SEG2… because bulk of the energies are lost in SEG0 and SEG1. Central pad index

Energy spread over pads e -,  =2, p T = 10 (GeV/c),  = Each box in plot corresponds to a single pad. So, only few pads get most of the deposited energy. Also, recollect minor leakage into SEG2 from SEG0 and SEG1.

Is 2x2 pad tile enough? It depends on , but OK for ALICE! 14  = 2.6 Next 3 pages use old convention. SEG (0,1,2)  (1,2,3)

Is 2x2 pad tile enough? It depends on , but OK for ALICE! 15  = 2.0

Is 2x2 pad tile enough? It depends on , but OK for ALICE! 16  = 1.6

Condition All particles in this study are with similar kinematics –  =2.0,  =0.174 Note MIP plays major role in energy distribution between W/Si/Other materials in FOCAL. Key differences in longitudinal energy deposition –  : Simple MIP – e/  : Full & early energy containment –  + /p : Fluctuation in the 1 st hadron interaction Hadron rejection factor ~1/200 p T = 10 GeV/c, just with longitudinal profile difference,   = 95% ) 17 Longitudinal shower development & Particle ID

Single hard e or  (EM Shower by many MIP+… ) 18 SEG0SEG1 SEG2 y z PADSTRIPW

Energy into FOCAL components e’s,  =2, p T = 10 (GeV/c),  = SEG0 SEG1 SEG2 WSiOthers % of energy in W

in – e,  (  =2.0,  =0.1745) in – e,  (  =2.0,  =0.1745) 20

y z SEG0SEG1 SEG2 PADSTRIPW Single hard hadron ( shower by  ’s from secondary  0 ’s +… ) 21

Energy into FOCAL components  +,  =2, p T = 10 (GeV/c),  = SEG0 SEG1 SEG2 WSiOthers % of energy in W Passing hadrons Interaction at SEG0 + SEG1 + SEG2

in –  +, (  =2.0,  =0.1745) in –  +, (  =2.0,  =0.1745) 23

E.M. & Hadronic signal together 24  /p/pbar

Used setting :  =2, p T = 10 (GeV/c),  = Selection – E 0 > 0.05 (selection 3) – E 1 > 0.12 (selection 2) – E 2 < 0.07 (selection 1) Resulting efficiency with caveat –  : 95% – p,  + : 0.5% – E sum for p,  + is smaller than that of e, .  There would be effectively bigger rejection than this number! 25 Can we identify e,  from hadrons(p,  + ) using longitudinal shower development?

E sum for  + and  surviving selection 1,2, % 95%