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

2.  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

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

4. 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

5. 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

6. PHENIX FOCAL Beam test 2009 6

7. Detector layout SEG2SEG1 SEG0 Preamp crate 7

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

9. 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

10. Sensor on a wafer 6 cm x6 cm 10 1.5cm x1.5 cm

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

12. 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),  =0.174 12 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

13. Energy spread over pads e -,  =2, p T = 10 (GeV/c),  =0.174 13 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.

14. 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)

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

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

17. 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

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

19. Energy into FOCAL components e’s,  =2, p T = 10 (GeV/c),  =0.174 19 SEG0 SEG1 SEG2 WSiOthers 1.1-1.6% of energy in W

20. in Si@FOCAL – e,  (  =2.0,  =0.1745) in Si@FOCAL – e,  (  =2.0,  =0.1745) 20

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

22. Energy into FOCAL components  +,  =2, p T = 10 (GeV/c),  =0.174 22 SEG0 SEG1 SEG2 WSiOthers 1.7-1.8% of energy in W Passing hadrons Interaction at SEG0 + SEG1 + SEG2

23. in Si@FOCAL –  +, (  =2.0,  =0.1745) in Si@FOCAL –  +, (  =2.0,  =0.1745) 23

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

25. Used setting :  =2, p T = 10 (GeV/c),  =0.174. 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?

26. E sum for  + and  surviving selection 1,2,3 26 0.5% 95%