•Identify hadrons with pT ≥ 10 GeV/c

•Inclusive measurement, particle yields, especially protons

•Weak identification, i.e. Π,K – protons can be enough

GOALS of the VHMPID

Evolution of "high pT" meaning

0

2

4

6

8

10

12

14

1998 2000 2002 2004 2006 2008 2010 2012

year

Hig

h p

T m

eani

ng

HMPID TDR

Start of LHC

Yesterday

First HI collision ?

Urs Wiedemann, HI Forum 10 February 2004

THE VHMPID,

UPGRADE or DOWNGRADE ?

Č Threshold counter ?

RICH ?or TIC ?

Nice detector but

the radiator is too long

(1m for <6> photons)

SIC TRANSIT GLORIA MUNDI

IMPROVED TIC1 (XXL momentum)

C4F10

CaF2

IP

HMPID CsI photo-cathode

Data from the HADES RICH (NIM A 433 (1999) 201-206)

Radiator thickness 36 to 65 cm, 12 to 22 photons detected

Quartz cut-off

Momentum Detector resp.

Particle id.

< 3 GeV 0 Who cares?

3 < p < 9 1 Π

0 K,p

9 < p < 17 1 Π,K

0 p

> 17 GeV 1 Who knows ?

C4F10 radiator

1.5 m

IMPROVED TIC2 (XXXL momentum)

CF4 (CH4)

CF4 + CsI give 40 photons with 50 cm radiator !

(Nucl. Instrum. Methods Phys. Res., A 523 (2004) 345-354)

Window less !

CF4 transparent down to 110 nm !

Momentum Detector resp.

Particle id.

< 5 GeV 0 Who cares?

5 < p < 16 1 Π

0 K,p

16 < p < 30 1 Π,K

0 p

> 30 GeV 1 Who knows ?

CF4 radiator

But aging needs to be investigated

if we want to get rid of the window

“Amazingly, extremely rapid aging has been observed for pure CF4 and in Ar/CF4/O2(50:40:10) mixture, which were expected to have strong etching abilities.”

“Finally, it should be noted, that most of the aging studiesin the CF4/hydrocarbon mixtures, were performed by irradiating a small region of the wire under well controlled laboratory conditions. At the same time, several painful experiences with aging are known from the high energy experiments.”

M.Danilov, L.Laptin, I.Tichomirov, M.Titov, Yu.Zaitsev

Aging tests of the proportional wire chambers using Ar/CF4/CH4(74:20:6), Ar/CF4/CH4(67:30:3)and Ar/CF4/CO2(65:30:5) mixtures for the HERA-B Muon Detector

Moscow 2000

“In this article we present evidence that the rapid aging observed is related to chemical processes at the cathode rather than at the anode, as previously suggested.”

J. Wise et al. J. Appl. Phys. 74 (Q), 1 November 1993

We are here

A word of hope …

Why not a GEM detector ? (perhaps with the ALTRO R/O)

Nucl. Instrum. Methods Phys. Res., A 535 (2004) 324-329Nucl. Instrum. Methods Phys. Res., A 523 (2004) 345-354

Much more challenging, a lot of R&D required

TWO STAGES TIC

CaF2 window

C4F10CF4

Window less !

Momentum

C4F10 CF4 Particle id.

< 3 GeV 0 0 Who cares?

3 < p < 5 1 0 Π

5 < p < 9 1 1 Π

9 < p < 16 1 1 Π

1 0 K

0 0 p

16 < p < 30

1 1 Π,K

1 0 p

> 30 GeV 1 1 Who knows?

C4F10 + CF4 radiators

But Cherenkov angles are very similar !

~2m

CF4C4F10

This will work but it would be too long and complicated

TWO STAGES TIC

CaF2 window

C4F10CF4

Window less !

First results from test beam

Rad #1

Rad #1+#2

50 cm + 50 cm

# of photons Total charge

Radiator #1

Radiator #2

~3 cm

~ 10 cm

50 cm + 50 cm

~2.5 cm

DELAYED IDENTIFICATION

C4F10 / CF4

CaF2

Run X days with C4F10 ,Y days with CF4

CF4

C4F10

3< p <9 NΠ ,NK+p

9< p <16 NΠ+K ,Np

p> 16 NΠ+K+p

CF4

5< p <16 NΠ ,NK+p

16< p <30 NΠ+K ,Np

p > 30 NΠ+K+p

9<p<16 NΠ , NK , Np16<p<30 NΠ+K , Np+ Identification

- IdentificationIndirect identificationCross-checked

COST: ~700 kCHF (from RICH TDR)

The HADES RICH

A FERRARI for ALICE

C4F10CF4

Window less !

CaF2 window Aerogel detector

Pad chamber, no CsI

For n = 1.01 ptrh 1, 3.5, 7 GeV/c for Π, K and p.

If we could reject Π we would have the high pT trigger we need !

Momentum

Aerogel C4F10 CF4 Particle id.

< 1 GeV 0 0 0 Who cares ?

1 < p < 3 1 0 0 Π

3 < p < 9 1 1 x Π

1 0 x K

0 0 0 p

9 < p < 16 1 1 1 Π

1 1 0 K

1 0 0 p

16 < p < 30

1 1 1 Π,K

1 1 0 p

> 30 GeV 1 1 1 Who knows?

IMPID + VHMPID

Why I don’t like aerogel

•Momentum range not appropriate •Poor photons yield low efficiency•Too sensitive to electron background•Too sensitive to noise•Too sensitive to spread in PMTs gain•Efficiency vs. track position•Particles traveling through the PMT•Very expensive

Why aerogel does not work

OPEN QUESTIONS (no matter the technology)

Single or double arm ?

Acceptance

Do we need a trigger? How to trigger ?

Do we know what we do ?We identify protons by NOT seeing a signal

Very dangerous !

How to convince people that what we DO NOT see

it is the truth ?

Time scale

Construction can’t start before 2006 (not even prototype)

No test beam at CERN before June 2006

Perfect time for simulationand

build a strong physics case

Conclusions•It is possible to extend the PID capability of ALICE up to 30 GeV/c making use of presently available technologies at reasonable cost in a reasonable time.

•Two radiators are very suitable.

•Simulation is needed in order to choose and optimize the detector layout.

•Simulation is needed in order to define the physics target and understand the physics requirements.

•Laboratory tests are needed in order to investigate the aging of CF4.

Further work on this subject is incompatible with

the present commitments of the (CERN) HMPID group.