# Presentation: 105881

## PHENIX High pt Upgrades-- Overview --

- Yasuo MIAKE for High pt Upgrade Team
- _[http://](http://utkhii.px.tsukuba.ac.jp/~highpt/)__[utkhii](http://utkhii.px.tsukuba.ac.jp/~highpt/)__[.](http://utkhii.px.tsukuba.ac.jp/~highpt/)__[px](http://utkhii.px.tsukuba.ac.jp/~highpt/)__[.](http://utkhii.px.tsukuba.ac.jp/~highpt/)__[tsukuba](http://utkhii.px.tsukuba.ac.jp/~highpt/)__[.ac.](http://utkhii.px.tsukuba.ac.jp/~highpt/)__[jp](http://utkhii.px.tsukuba.ac.jp/~highpt/)__[/](http://utkhii.px.tsukuba.ac.jp/~highpt/)__[~highpt](http://utkhii.px.tsukuba.ac.jp/~highpt/)__[/](http://utkhii.px.tsukuba.ac.jp/~highpt/)_

## Proposal

- To enhance the PID capability of PHENIX, we like to install Aerogel counters (160 segments) on the West Arm.
- Together with the Aerogel, TOF and RICH, we can extend the PID beyond 5 GeV/c.

## Proposed Extention of  PID with Aerogel

|  |  | Pion-Kaon
separation | Kaon-Protonseparation |
| --- | --- | --- | --- |
| TOF |  ~100 ps
 | 0 - 2.5  | - 5 |
| RICH |  n=1.00044
 th~34 | 5 - 17 | 17 - |
| Aerogel |  n=1.011
 th~6.8 | 1 - 5 | 5 - 9 |

**Note ;**** Aerogel **_**together with TOF**_** can extend the PID capability upto 10 GeV/c**
**(Without TOF, no K-proton separation at < 5 GeV/c) **

## Physics Motivations

- From basic strategy, it is natural extension for PHENIX to extend its PID in higher pt region.
- Strong motivation given;
- Jet Quenching!?
- Large suppression of pions at high pt , while protons show binary scaling!?
- Meson/baryon puzzle?
- Need to extend PID > 5 GeV/c

## Transition Region to Jet Fragmentation

- Hadronic Flow vs Flow at Quark Level?
- Seems to important to measure the transition region to Jet fragmentation.
- PID (pion, kaon, proton)  beyond 5 GeV/c is the goal.

## What STAR is doing

- We like to go beyond 6 GeV/c with pion, kaon and proton.

## Aerogel Panel o the West

- 4.5 m from the vertex.
- Coverage ; full z, ** degree in phi.
- Space available for new TOF.

- 160 Cells

- Aerogel
- (11x22x11 cm^3)

- Integration
- Volume

- PMT

- PMT

## Design of Aerogel Panel

- Direction of every other cell is reversed, so that
- Aerogel locates at the same distance from the vertex,
- No dead space in between.

- Side View

- Z

- Top View

- rφ

- r

## Cell Design

## PMT assembly (prototype)

## Silica Aerogel

- Best index with RICH(CO2) is n< 1.007, too small.
- SP-12M (Matsushita)
- Silica aerogel with Lowest refractive index commercially available.
- Hydrophobic
- Long term stability proved by KEK-Belle.

| Refractive Index (Measured) | 1.0114 +- 0.0008 |
| --- | --- |
| Density [g/cm^3] | 0.04 |
| Transmission for 10 mm (Measured) | 64 % @ 400 nm88% @ 550 nm |
| Tile Size [mm] | 112.5 x 112.5 x 11.0 |

## PMT 

- PMT

- 3” PMT for photon counting
- Gain of > 10^6 at 1500 V w. 1-1-1-1- voltage divider
- One p.e. resolution

## Bleeder

- Hand made bleeder
- Thinner material
- Less space
- Less power (330 mW@1500V) than Hamamatsu standard
- Tested upto 3.2 kV for 6 hours

## Magnetic Field on the West

- Magnetic field of the location measured as < 8 G.
- Goal set as 16 Gauss !
- Thickness & Size of the mu-metal shield has been optimized using Helmholz Coil.

## Mu-metal Shield

- Magnetic shield of 0.2 mm thick breaks down at around 10 G.
- Loss of Gain &
- Loss of Q.E.
- Magnetic shield of 0.5 mm survive till 20 G.

## Final Prototype Test at KEK

- SP-12M
- R6233-01HA w. Bleeder
- Pre-Amp w. cables
- Dubna Box
- Normal ~ 14 p.e.
- Reverse ~ 12 p.e.

## Observed Clean Signal

- Very clean separation
- Amount of photons other than Aerogel Chrenkov is small!

- +2 GeV/c

- 1 p.e. peak

**~0.4 p.e./PMT**

**~6.6 p.e./PMT**

- Final Prototype Test

## Observed Uniform Response

- Uniform response, thanks to Integration Volume
- Important to separate in the momentum region of slow rise
- ~10% diff. between normal/reverse, due to diffusive nature of aerogel

## Uniformity Confirmed at Dubna

- Tested at Dubna with final prototype, but with SP-15.
- Independent setup & calibrations

## Cherenkov Light from PMT window 

- Cherenkov from PMT window;
- Huge pulse height
- Faster Timing (> 5 ns)

## Background Rejection

- Photons from PMT windows can be identified/recognized by itself,
- Faster Timing (>5 ns)
- Consistent with optical simulation
- ADC-ADC correlation
- Other sources of photons are carefully surveyed and <1p.e.
- TDC-TDC difference can be used for track association.

## Simulation for PID Performance

- Assumptions;
- HIJING Au+Au 200 GeV
- Aerogel;
- n =1.011
- Saturated at 14 p.e. w. poissson distr.
- Occupancy 10%
- RICH ;
- n =1.0044 (CO2)
- Saturated at 10 p.e. w. poissson distr.
- Occupancy 3.4 % (NIM)

## Expected Proton Identification

- Require No-Aerogel & No-RICH

- Occupancy

## Expected Kaon Identification

- Require Aerogel & No-RICH  (Need TOF for < 5 GeV/c)

## PISA Activity

- All the known material put into PISA.
- Occupancy ~ 8 %

## Radiation Length by PISA

- <Lrad>  ~20 %
- Similar to TOF

- Radiation Length [%]  -->

## Safety Issues

- Known issues; PMT-holder, HV protector

| Item | Fire | Electrical | Status |
| --- | --- | --- | --- |
| 1) Aerogel             
2) Nyron(MC901)       
3) Aluminum               
4) Mylar
5) Gore-tex
6) PMT-Bleeder (G10) | -
Estimated ?
-
?
-
- | -
-
-
-
-
3.2 kV | New
New
-
-
-
Tested |
| 7) Signal connector PreAMP
8) Signal connector Box
9) H. V. Connector
10) LED connector | UL94V-0
UL91V-0/ UL94-0
UL94V-0
UL94V-0 | 300 V
3 kV
3 kV
600 V | New
Used at EMCal
Used at EMCal (but 3-pin)
(Small type of ) |
| 11) Signal cable to PreAMP
12) Signal Cable from PreAMP
13) High voltage cable
14) LED cable
15) L. V. cable for PreAMP | UL ?
?
?
UL-E108898
? | 

?

? | 
New
New
LAN cable (Category-5E)
? |

## Aerogel/PMT Preparation at Tsukuba

## Box Production/Inspection at Dubna

## Dubna Contributions

- Dubna contributions have been very important from R&D’s to productions.

## Backups

## Jet Quench via Flavor Dependences

- Gluons in QCD stronger interaction than quarks
- Gluon density in nucleon larger in small x, &  gg > qq
- Larger energy loss of gluons than that of quarks
- dEq/dx  < dEg/dx
- At high pt, some particles are fragmented more from gluon than quark jet.
- Gluon jets fragment into same number of particles and anti-particles.
- Gluon jets produce more particles ; softer distr.
- Effect of jet qunching can be seen in particle ratios.
- As an example, anti-proton/proton ratio..

**PRC58(98)2321**

**Nucl.Phys B420(94)583**
**PRD51(95)3436**

*Good demonstration of importance of PID at high pt region*

## Occupancy Estimation

- TOF
- ~ 100 cm2 at 5 m
- Sensitive to all > 150 MeV/c
- Backgrounds (low energy e/’s  from yoke & EM cal)
- Occupancy 10% in Au+Au
- Aerogel of n = 1.01
- Sensitive to all  > 7.1
- Delta rays in Aerogel (~%)
- Muon from decayed pion
- Backgrounds
- Using RQMD pt distr., occupancy of Aerogel estimated;
- 10 % for 300 cm2 @ 4m
- 5 % for 150 cm2 @ 4m

- Estimation from pt distr. (RQMD)

|  | TOF
(pt>0.18) | Aerogel
(pt>0.75) |
| --- | --- | --- |
| Multiplicity  | 158 k | 33 k |
| Segmentation | 100 cm2 at 5m | 300 cm2 at 4m |

**ShinIchi Esumi**