PHENIX High pt Upgrades Recent Progress

1. PHENIX High pt UpgradesRecent Progress Yasuo MIAKE For High pt Upgrade Team http://utkhii.px.tsukuba.ac.jp/~highpt/

2. Plan Guestimate If we install on the East, • Coverage of 4 TOF panel equivalent as a first stage • 150 modules • 300 PMT’s ; 12,000,000 yen • 400 liter; 20,000,000 yen • Total ; ~40,000,000 yen • Since no space on the East, we install on the West. • Remove 2 lower TOF panels from the East after successful pp measurements • 1 spare panel • 1 panel to be constructed • TOF 1 panel ; 13,000,000 yen TOF 1 panel ; 0.5 m x 2 m

3. Additional Cherenkov • RICH • CH4;1.00044 • CO2;1.00041 • gth= 34 • Pion ; 4.7 GeV/c • Aerogel • Best match at 1.005 • Commercially available for 1.007 - 1.07 • Samples for test • 1.007 • 1.01 • 1.015 Pion Kaon

4. 0 0 0 0 0 0 4 4 4 4 4 4 8 8 8 8 8 8 Extended PID Aerogel together with TOF can extend the PID capability upto 10 GeV/c (Without TOF, no K-proton separation at < 5 GeV/c)

5. Aerogel Cherenkov at KEK-B BELLE • Non-imaging Cherenkov • 960 modules at Barrel, 228 at Endcap. • Index n = 1.01 - 1.03 • 12 x 12 x 12 cm3 • 2 Fine-mesh PMT (1.5T) • R6683(3”) for n = 1.01 • R6682(2.5”) for n = 1.015 • R6681(2”) for n = 1.02 • ~ 10 - 20 p.e. Journal of Non-Crys.225(1998)369

6. KEK Beam Test Setup TOF for hadron PID • Particle Identification • Gas C for electron • TOF for hadron ID • KEK pi-2 channel • 1 - 4 GeV/c for momentum scan Gas C for electron tagging KEK-PS T496 Dec. 12 - 21, 2001

7. Photos (1) • Many vistors, many students! It was fun!

8. Photos (2) T. Takagi T. Ohki M. Ono M. Konno T. Takagi

9. PMT selections Nucl.Inst.Meth. 406(1998)213 R329 • PMT Requirements • Photon counting • Gain; > 10**6 • Low dark current • Larger diameter • Cost • Hamamatsu recommended • 2” ; R6231 • 3” ; R6233 • UV PMT for the KEK test • R2059 ( 160 - 650 nm) • Russian PMT’s ? R6231 R6233

10. Pulse height distr.of single p.e.’s • 2” R6231 • Clean single photoelectron peak seen. • Gain of 2x10**6 will be obtained. • Done by Hamamatsu • Will be tested at Tsukuba

11. Index of Aerogel • Commercially available • Matsushita-Denko • ~50k yen / litter • For the test experiments, n=1.007 -8, 1.015, 1.020 have been purchased for the tests. • Index measurements done. • Masahiro Konno

12. Measurement of Refractive Index • Surface condition of the sample dominates the error. Masahiro Konno

13. 532 nm 415 nm 355 nm Measurements of Transmission Laser 355nm 415nm 532nm • Shorter transmittance for shorter wave length. • Shorter transmittance for smaller index. Measured Transmittance [cm]

14. Picosec Pulser (Hamamatsu) 415 nm HV 1800V 4.2 pe Calibration of PMT • Using solid state laser pulser (415 nm), PMT’s were calibrated before and after the KEK test. • Measurements at various HV’s give consistent results. PMT

15. Belle Type Collect scattered photons Non-directional lights Area of photocathode/cell size 2 PMT per cell more expensive Mirror Type Collect direct photons Directional lights Efficient way to get light!? Sophisticated mirror design?! Easy to get larger cell size 1 PMT per Cell Cheaper Two Type of Designs Mirror Type Belle Type

16. β = 0.9989 β = 0.9544 Aerogel Signal for protons and pions +3 GeV/c n=1.017 • Clear separation of protons and pions observed. Pions Protons PID by TOF successful

17. Features of Cherenkov Emission Np.e. vs. Index Np.e. vs. Momentum • It is Cherenkov Emission. Belle ;Goretex m = 0.14 n = 1.017 Belle; Tyvek m = 0.14 p = 3.0

18. Belle Type (1) Reflector n = 1.017 R6233 (3”,non-UV) • Three types of reflector. • Tyvek • Millipore • Goretex • Offline optical measurements at BNL says “Tyvek is good” • Effect of reflector • Without reflector, < 1/4 • Reflector is essential for Belle Type 3 GeV/c pions

19. n = 1.017 R6233 (3”,non-UV) 3 GeV/c pions Belle Type (2) Position Dep. • With Goretex, >25 p.e. obtained everywhere. • In each PMT, exponential behaviour is observed. • Goretex ; λ= 7.0 cm • Tyvek ; λ= 5.5 cm • Exponential shape may not be trivial issue? Goretex x

20. n = 1.017 R6233 (3”,non-UV) 3 GeV/c pions θ Belle Type (3) Angular Dep. • Seems to be proportional to the thickness of the aerogel. • Scattered photons have no directionality.

21. Belle Type (4) Area of Photocathode n = 1.017 • Put Iris-plate in front of the photocathode. • Roughly proportional to the area of photocathode, S • Scattered photons have no directionality. • Then, saturate with larger PMT coverage R6233 (3”,non-UV) S Iris 3 GeV/c pions

22. n = 1.017 L R6233 (3”,non-UV) 3 GeV/c pions Belle Type (5) Thickness Dep. • Photons proportional to the thickness of the aerogel. • Consistent with; • Angular dependence • No directionality

23. Larger Cell of Belle Type n = 1.017 • Using exponential behaviour, we can estimate the performance for larger cell of Belle Type. • Smallest at the center • We can estimate performance of Belle Type for any size, any thickness. D R6233 (3”,non-UV) 3 GeV/c pions Npe at the Center D

24. Mirror Type n = 1.017 R6233 (3”,non-UV) 3 GeV/c pions Mirror Type (1) Shape of Mirror • Flat vs Parabola Mirror • Aluminized mylar sheet with styro foam backing (hand made) • No significant difference at the center as expected from the cone angle of 10 degree.

25. n = 1.017 R6233 (3”,non-UV) 3 GeV/c pions Mirror Type (2) Position Dep. • Expected Position Dep. • Relation of Cone angle ~ 10.1 deg. and PMT size • Expected diameter ~ 3” PMT • Broad peak at the center • No significant difference between Flat and Parabola mirrors.

26. Mirror Type (3) Thickness Dep. • Saturate! • Difficult to get more p.e. • Due to short transmittance L R6233 (3”,non-UV) n = 1.017 Mirror Type 3 GeV/c pions

27. n = 1.017 R6233 (3”,non-UV) n = 1.017 R6233 (3”,non-UV) 3 GeV/c pions 3 GeV/c pions Bell vs Mirror • Even with Mirror type, reflector is important !

28. (a) (b) Directional vs Scattered Photons (b) (a) • Is the worse results with mirror type due to bad mirrors? • Note that it is hand made with aluminized mylar sheet. • Other way to measure Directional/Scattered photons. • Rotate Belle Box and put the beam straight to aerogel and PMT. • To remove signals from PMT window, subtract (b) from (a). PMT Aerogel Empty Beam

29. 17 p.e. 6 p.e. 8 p.e. Measurements with 2” PMT n=1.017 2” PMT 3 GeV/c Tyvek • Assume uniform angular distribution of scattered photons. • Out of 17 p.e. (straight beam geometry), 8 p.e.’s are scattered photons.

30. 22 p.e. 8 p.e. Measurements with 3” PMT n=1.017 3” PMT 3 GeV/c Tyvek • Guestimate of scattered components in straight geometry • 8 p.e. x *(8 p.e./6 p.e.) = 11 p.e. • Thus, direct photons in straight geometry are 11 p.e., which is similar to direct photons observed with 2” PMT. • Consistent with cone angle of 10 degree. Not measured!

31. Use of UV PMT Tyvek, n=1.015 • Assuming cherenkov from uniform radiator, use of UV pmt will gain a factor of 2. • Increase of 25 % observed with the straight beam measurements. • Not uniform at the level of 200 nm?

32. Use of wavelength shifter • Wavelengthshifter may increase the overall photon yield. • Thanks to Prof. Peressedov, we could try POPOP at KEK. • Powder on aerogel surface • Larger tail appeared with POPOP for pions! • Note POPOP localized only on the surface of Aerogel. !

33. Use of POPOP powder • Additional tail also appeared for protons. • Scintillation ? • But, it is smaller tail than for those of pions. • Need to investigate a way to uniformly distribute POPOP over the large volume not only the surface of Aerogel.

34. Novosibirsk vs Matsushita n=1.007 2” PMT With Non-UV PMT (R6231) With UV PMT (R2059)

35. Belle Type It works; > 20 p.e. We can estimate performance of Belle Type with any cell size, any thickness. We understand pretty well. Mirror Type ~ 10 p.e. Direct photons at most 10 p.e. Is there a better way to combine direct and scattered photons? Otherwise, Belle Type seems to be the best. Needs to be studied Better mirror? (I’m pessimistic) UV vs. non-UV PMT PMT selections Gain too low? Russian PMT? Test of electronics Use of PMT amp? Summary of KEK test

36. West Arm East Arm PHENIX GEANT Calculation T. Takagi • Belle Type Aerogel counter installed in PISA.

37. beam line z (cm) magnet Aerogel RICH mirror x (cm) GEANT results • Occupancy of 5 % seen in central Au+Au collisions (HIJING) Backgrounds Number of fired cells per event

38. Optical Model

39. (1) In December 2001, test experiment for the Aerogel Cherenkov have been carried out at KEK with visitors from Dubna. (2) Both Belle type (aerogel w. 2 PMT's on the side) and Mirror type (mirror followed by 1 PMT behind the aerogel) have been tested. So far, best results (>20 p.e.) obtained from Belle type with 3" PMT's and Goetex as reflector, which is our backup solution now. (3) We will continue R&D and test experiments for both mirror and Belle type. (Next test beam will be before the summer.) (4) For the deltailed analysis of optical properties of the Aerogel, such as wavelength dependences of absorption length & scattering length, study with a laser and spectrometer is also in progress. (5) Comparison of Aerogel from Matsushita and Novosibirsk gives interesting results; while similar results obtained when non-UV PMT was used, Novosibirsk Aerogel provides 20 - 30 % larger signal than that of Matsushita with UV PMT (Quartz window). As is reported in literature, Novosibirsk aerogel seems to have better optical transmission in UV. (According to Sumiyoshi at KEK, master of aerogel, more complicated process is adopted for production of aerogel at Novosibirsk.) Summary of Status