RPC RPC upgradeupgrade for the HADES for the HADES

Tracking: MDC

e-,e+ identification with RICH- TOF/PreShower

<450 and p>0.4 GeV/c TOF is not sufficient- Pre-Shower

p, identification TOF-Tracking

RICH

MDC I/II

coils

HADES’2003 TOF walls

Outer TOF wall >450:

6 * 64 scintilator rods. TOF & position measurement

t : 120 ps , x2cm dE/dx measurement

TOFINO

Pre-Shower

target

Inner TOF wall <450:

6 * 4 scintilator paddles TOF measurement

t : 550 ps, no x dE/dx measurement

p [MeV/c]

Fra

ctio

n o

f id

enti

fied

π+

π+

pfakefake π+

other

Inner Inner TOF performanceTOF performance in in C+C@2AGeVC+C@2AGeV

TOF [ns] TOF [ns]

Hadron id Lepton id

q*p

[M

eV

/c]

RICH

Pre-Shower

Pion id

double elec. hits

• no e/ separation by TOF : only with RICH+PreShower: e+ for p<0.4 GeV/c )

• TOF measurement limited to light systems (C+C)-double hits!

• no spatial resolution (pair analysis!)

• /p separation for p< 1 GeV/c

• no K/ separation

Resistive Plate Counters for HADESResistive Plate Counters for HADES

Requirements for an RPC TOF detector for HADES:

-Adequate granularity (HI collisions)- double hit probability<10%

6 sectors: 660 counters with 4 gaps (99% efficiency)

-Time resolution below 100 ps :

e/ separation for p<0.4 GeV/c (95% CL)

/p separation

/K separation for p<1.GeV/c (99% CL)

-Space resolution around S=3 cm2

electron pair analysis.

-Stable behaviour at rates of few hundreds of Hz/cm2 and in presence of high ionising particles

high resistive glass (2.5mm thick)

Negligible cross talk

Isolated detector modules

Physics cases for new TOFPhysics cases for new TOF• High intenisty pion beams:

o continuation of HADES pion programme : dielectron production in -p (proposal S262): -pe+e-n, -pR / n (/ coupling to S11(1535),

D13(1520))

Beam intenisty I- = 4*106/spill(4s)

to exclusive +p reactions: +pR / p +

@1.3 GeV/c „subthreshold omega”- „deflation” D37(1930),F37(1930)

@ 2.35 GeV/c electromagnetic 0e+e- form-factor (VDM „puzzle”)

Beam intenisty I+ =5.2*106/spill (4s) @1.3 GeV/c, 3.6*106/spill@2.35 GeV/c

p/ separation at high momentum

o @ 1.3 GeV/c Recoiless production in - Pb collisions (in-medium effects)

o Weak-electromagnetic structure of hyperons

+ pK++ K+ Xe+e- (1.8 GeV/c) Kaon tagging ! Increase of pion beam intensity

physics. OZI rule violation in pion and proton induced reactions.

identification via kaon decays

Physics cases with new TOFPhysics cases with new TOF

• HI collisions above C+C @1-2 AGeV

• HI collisions at new SIS facility C+C @ 8AGeV

• same detector geometry

• Similar LVL1 rate

• Slightly higher p/+ momenta in forward TOF

• 15k /5 day run

RPC geometryRPC geometry

Top view of one sector

• electron identification > 0.9 even for 1 AGeV Au+Au

• Rate < 700 Hz/cm2 for Au+Au 108 ions/spill

RPC prototype performance @2AGeV RPC prototype performance @2AGeV C+CC+C

Gas admixture: 98.5% C2H2F4 + 1% SF6 + 0.5 isoC4H10

160cm long

4 gaps

0.3cm gap

Cross talk < 0.4%

RPC read-outRPC read-out

Front-end on detector (preamp, shaper,discriminator) – commercial components-tested in beam

2 time read-out/ module (1320 TDC channels)

1 charge /module (660 ADC or Time over Threshold)

CAEN 132 channel multi-hit TDC („plug and play”)

F1-TDC multi-hit digital TDC + fast internet controler (development)

GSI TAQUILA (development)

Proposals in evaluation by HADES DAQ (decision about prototypes in February 2003)

Project organisation and cost Project organisation and cost estimateestimate

• Detector construction: LIP Coimbra, Univ. Santiago, INR Moscow

• Front-end :Univ. Santiago, CIEMAT-Madrid

• Digitial read-out and DAQ: GSI, Univ. Giessen, Univ. Cracow

1 sector prototype scheduled on autumn 2004

Detector mat. 100 k€

Machining 80 K€ 180 k€ Det.mechanics 30 k€

LV,HV 35 k€

Gas system 15k€ 80 k€ Front-end 60 k€

Digitizers+DAQ 120 k€ 180 k€ 440 k€ + 2Phd positions

Investment: