PHENIX High pt Upgrades Recent Progress Yasuo MIAKE For High pt Upgrade Team

2 Yasuo MIAKE, Univ. of Tsukuba Plan Guestimate 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 If we install on the East,

3 Yasuo MIAKE, Univ. of Tsukuba Additional Cherenkov RICH –CH4; –CO2;  th = 34 Pion ; 4.7 GeV/c Aerogel –Best match at –Commercially available for Samples for test –1.007 –1.01 –1.015 Pion Kaon

4 Yasuo MIAKE, Univ. of Tsukuba Extended PID Pion-Kaon separation Kaon-Proton separation TOF  ~100 ps RICH n=  th~ Aerogel n=1.007  th~ Aerogel together with TOF can extend the PID capability upto 10 GeV/c (Without TOF, no K-proton separation at < 5 GeV/c)

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

6 Yasuo MIAKE, Univ. of Tsukuba KEK Beam Test Setup 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 TOF for hadron PID KEK-PS T496 Dec , 2001

7 Yasuo MIAKE, Univ. of Tsukuba Photos (1) Many vistors, many students! It was fun!

8 Yasuo MIAKE, Univ. of Tsukuba Photos (2) M. Konno T. Takagi T. Ohki M. Ono

9 Yasuo MIAKE, Univ. of Tsukuba PMT selections 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 ( nm) Russian PMT’s ? R329 R6231R6233 No.CostA few>400>800 R623145,00040,50031,50029,200 R623352,00046,80036,40033,800 Nucl.Inst.Meth. 406(1998)213

10 Yasuo MIAKE, Univ. of Tsukuba 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 Yasuo MIAKE, Univ. of Tsukuba Index of Aerogel Commercially available –Matsushita-Denko ~50k yen / litter For the test experiments, n= , 1.015, have been purchased for the tests. Index measurements done. –Masahiro Konno No.IndexMeasured SSP- 30D SP-15A SP-15B SP-20A SP-20B SP SP

12 Yasuo MIAKE, Univ. of Tsukuba Measurement of Refractive Index Surface condition of the sample dominates the error. Masahiro Konno

13 Yasuo MIAKE, Univ. of Tsukuba Measurements of Transmission Shorter transmittance for shorter wave length. Shorter transmittance for smaller index. Laser 355nm 415nm 532nm 355 nm 415 nm 532 nm Index nm nm nm Measured Transmittance [cm]

14 Yasuo MIAKE, Univ. of Tsukuba 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. HV 1800V 4.2 pe Picosec Pulser (Hamamatsu) 415 nm PMT

15 Yasuo MIAKE, Univ. of Tsukuba Two Type of Designs Belle Type –Collect scattered photons Non-directional lights Area of photocathode/cell size 2 PMT per cell –more expensive Belle Type 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

16 Yasuo MIAKE, Univ. of Tsukuba Aerogel Signal for protons and pions Clear separation of protons and pions observed. β = β = PID by TOF successful +3 GeV/c Pions Protons n=1.017

17 Yasuo MIAKE, Univ. of Tsukuba Features of Cherenkov Emission It is Cherenkov Emission. Belle; Tyvek m = 0.14 p = 3.0 Belle ;Goretex m = 0.14 n = Np.e. vs. Momentum Np.e. vs. Index

18 Yasuo MIAKE, Univ. of Tsukuba Belle Type (1) Reflector 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 Reflector PMT1 (p.e.) PMT2 (p.e.) Total (p.e.) Goretex Millipole91019 Tyvek8816 Black Paper GeV/c pions n = R6233 (3”,non-UV)

19 Yasuo MIAKE, Univ. of Tsukuba 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? 3 GeV/c pions n = R6233 (3”,non-UV) Goretex x

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

21 Yasuo MIAKE, Univ. of Tsukuba Belle Type (4) Area of Photocathode 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 3 GeV/c pions n = R6233 (3”,non-UV) Iris S

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

23 Yasuo MIAKE, Univ. of Tsukuba Larger Cell of Belle Type 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. 3 GeV/c pions n = R6233 (3”,non-UV) D D Npe at the Center

24 Yasuo MIAKE, Univ. of Tsukuba 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. Mirror ShapeNpe Flat9 Parabora9 Mirror Type 3 GeV/c pions n = R6233 (3”,non-UV)

25 Yasuo MIAKE, Univ. of Tsukuba 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. 3 GeV/c pions n = R6233 (3”,non-UV)

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

27 Yasuo MIAKE, Univ. of Tsukuba Bell vs Mirror Even with Mirror type, reflector is important ! Mirror ShapeNpe Flat (Tyvek)9 Parabora (Tyvek)9 Parabora (Goretex)14 3 GeV/c pions n = R6233 (3”,non-UV) Reflector PMT1 (p.e.) PMT2 (p.e.) Total (p.e.) Goretex Millipole91019 Tyvek8816 Black Paper GeV/c pions n = R6233 (3”,non-UV)

28 Yasuo MIAKE, Univ. of Tsukuba Directional vs Scattered Photons 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 (a) (b) (a) (b)

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

30 Yasuo MIAKE, Univ. of Tsukuba Measurements with 3” PMT 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. 22 p.e. 8 p.e. n= ” PMT 3 GeV/c Tyvek Not measured!

31 Yasuo MIAKE, Univ. of Tsukuba Use of UV PMT 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? Non-UV (R6231) nm 17 p.e. UV (R2059) nm 21 p.e. Tyvek, n=1.015

32 Yasuo MIAKE, Univ. of Tsukuba 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 Yasuo MIAKE, Univ. of Tsukuba 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 Yasuo MIAKE, Univ. of Tsukuba Novosibirsk vs Matsushita With Non-UV PMT (R6231) With UV PMT (R2059) n= ” PMT

35 Yasuo MIAKE, Univ. of Tsukuba Summary of KEK test 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?

36 Yasuo MIAKE, Univ. of Tsukuba GEANT Calculation Belle Type Aerogel counter installed in PISA. T. Takagi PHENIX East ArmWest Arm

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

38 Yasuo MIAKE, Univ. of Tsukuba Optical Model

39 Yasuo MIAKE, Univ. of Tsukuba Summary of Status (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 % 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.)