PHENIX High pt Upgrades

Recent Progress
　(April Core Week)


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

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

Extended PID

Measurements of Transmission


	Shorter transmittance for shorter wave length.
	Shorter transmittance for smaller index.

Wave Length Dependece


	Consistent with Rayleigh scattering.
		Scatt. dominant
		Small absorption
	Well known as optical property of Aerogel

Two Design Concepts


KEK-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
Should be easier to stack

KEK Beam Test Setup

Aerogel Signal for protons and pions


	Clear separation of protons and pions observed.

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

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.
	Attenuation may be due to property of reflector rather than that of aerogel itself.

Belle Type (3) Angular Dep.


	Seems to be proportional to the thickness of the aerogel.
		Scattered photons have no directionality.

Belle Type (5) Thickness Dep.


Photons proportional to the thickness of the aerogel.
	Consistent with;
		Angular dependence
		No directionality

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 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.

Mirror Type (3) Thickness Dep.

Bell vs Mirror


	Even with Mirror type, reflector is important !

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).

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.

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 collect 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?
First priority of the next test;
	Effect of integration sphere behind the aerogel.

Participation of JINR-LHE, Dubna

Participation of JINR-LHE, Dubna


	Will have official Agreement between Dubna and Tsukuba for High pt project.
	Their participation;
		Mechanical design
		Mechanical constr.
		etc etc
	Next KEK Test in May
		S. Afanasev
		V. Peressedov
		L. Zolin