SIDDHARTA: the future of exotic atoms SIDDHARTA: the future of exotic atoms research at DAresearch at DANENE

SiSilicon licon DDrift rift DDetector foretector for H Hadronic adronic

AAtom tom RResearch by esearch by TTiming iming AApplicationspplications

 

DAFNE-2004: Physics at meson factories

Mihai IliescuMihai IliescuINFN-LNF

10-06-2004

  

The goal of KH and KD measurementsThe goal of KH and KD measurements

a few eVa few eV determination of both shift and width of the 1s determination of both shift and width of the 1s

level induced by the strong interaction in the Kp and KDlevel induced by the strong interaction in the Kp and KD

atomic systemsatomic systems

The main feature to deal with, in order to obtain the The main feature to deal with, in order to obtain the

desired accuracy, is the desired accuracy, is the S/B ratio.S/B ratio.

This requires to pass from This requires to pass from 1:701:70 (KH today)(KH today)

to at least to at least 1:1 (KH)1:1 (KH) and and 1:5 (KD-first time)1:5 (KD-first time)

Experimental requirements Experimental requirements for the measurementsfor the measurements

a triggerable,a triggerable, large area, high resolution, high efficiency large area, high resolution, high efficiency

in the energy region of interest (1-20 KeV) in the energy region of interest (1-20 KeV)

X-ray detectorX-ray detector

Triggerable SDDsTriggerable SDDs

A large area Silicon Drift Detector (SDD), equipped withA large area Silicon Drift Detector (SDD), equipped with

trigger electronics, presently under developmenttrigger electronics, presently under development

(SIDDHARTA project), satisfies the experimental (SIDDHARTA project), satisfies the experimental

requirementsrequirements

Working principles of the SDDWorking principles of the SDD

The classical PIN (Positive-Intrinsic-Negative) diode detector

The anode capacitance is proportional to the detector active area

n

n+

p+ -Vcc

ANODE

Entrance window

n

n+

p+ -V cc

p+

The Semiconductor Drift Detector

AnodeThe electrons are collected by the small anode,characterised by a low output capacitance.

Advantages: very high energy resolution at fast shaping times, due to the small anode capacitance, independent of the active area of the detector

The Silicon Drift Detector with on-chip JFET

JFET integrated on the detector• capacitive ‘matching’: Cgate = Cdetector

• minimization of the parasitic capacitances• reduction of the microphonic noise• simple solution for the connection detector-electronics in monolithic arrays of several units

The integrated JFET

Detector produced at Max-Planck-Institute for Extraterrestrial Physics, Garching, Germany

Performances of the SDDsPerformances of the SDDs

Quantum efficiency of a 300 m thick SDD 55Fe spectrum measured with a SDD (5 mm2) at –10°C with 0.5 s shaping time

Silicon Drift Detector QE and resolution

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1100

200

300

400

500

600

700

800

A (cm-2)

FW

HM

(eV

)

SDD PIN Si(Li) 150 K 5.9 keV line

PIN Tsh=20us

Si(Li) Tsh=20us

SDD Tsh=1us

Spectroscopic resolution: detector comparison - 1

FWHMmeas of monoenergetic emission line 5.9 keV1cm2 detector at 150 K

SDD FWHM=140eV shap =1sSi(Li) FWHM=180eV shap =15s PIN diode FWHM=750eV shap =20sCCD FWHM=140eV frame= ~ s

Spectroscopic resolution: detector comparison - 2

10-2

10-1

100

101

10-8

10-7

10-6

10-5

Area (cm2)

Tdr

ift (

s)

Drift time vs. Active area

A=0.1cm2 Tdrift = 70ns

A=0.5cm2 Tdrift =350ns

A= 1cm2 Tdrift =700ns

With: = 2k/cmH = 450m

Timing resolution with SDD

2

2

HN

A

qTdrift

Dn

s

hIK

IA

h

tIA

tdr max

Timing with the anode signal

Triggered acquisition

Kaontrigger

Concidencewindows

Detectedpulses

Consideredpulses

Kaon trigger X-ray pulseBackground pulse

Tdr max

Background reduction with triggered acquisition

Machine Background

= number of detected kaons per detected K X-ray = 103

Br = background rate = 103 events/s over 200 cm2, full

spectrum (1-20 KeV) -->50 Hz/1KeV

Tw = gate window

Tw = x Tdrift max = 103 x 1 s = 1ms

B = Br x Tw = 50 s-1 x 10-3 s = 5 x 10-2

S/B=20/1 negligibleHadronic background (Kp- interaction, synchronous)

preliminary simulation (typical SDD thickness 300 m)

S/B = 5/1 (KH), 1/4 (KD)

SDD test setup electronics layout

SDD canister

Scintillators

P.S.

Temp.control

7 Shapers, peak stretchers& discriminators

DAQ

Trigger(NIMlogic)

NIM2TTL

AmplifiedSDD output signal

Trigger signal

Stretcher reset

Analog output

Discrim. outputShapers control motherboard

HVcontrol

Test of the 30 mm2 SDD

CurrentVoltageelectrode

400A+12 VDrain

-gndIS,OS

20.9A- 178 VR#N

<0.1A- 91 VBack

0.5A- 18 VIGR

20.8A- 10 VR#1

Detector biasing parameters

5000 5500 6000 6500 7000Energy [keV]

0

1000

2000

3000

4000

Cou

nts

139 eV FW H M T = - 40°C, tsh=0.75s

beam pipeand kaon trigger

vacuum chamber

feed-throughs forSDD electronics

port forSDD cooling

targetcooling line

SDD pre-amplifierelectronics

SDD detector chip

target cell

lead table

SIDDHARTA setup version 1SIDDHARTA setup version 1

Beam pipe

Cryogenic target cellKaon trigger

SIDDHARTA setup version 2SIDDHARTA setup version 2

e+

e-

SDDs array

Kaon stopping distribution inside hydrogen target for a toroidal setup

Kaons stopped inside target ~ 30% (all generated)

Signal: ~ 30 times more than in DEAR

SIDDHARTA Kaonic hydrogen simulated spectrum

Precision on shift ~1 eV

integrated luminosity60 pb-1

S/B = 5/1

SIDDHARTA Kaonic deuterium simulated spectrum

Precision on shift < 10 eV

integrated luminosity100 pb-1

S/B = 1/4

SIDDHARTA collaborationSIDDHARTA collaboration

LNF, Frascati (Italy)LNF, Frascati (Italy)

MPE, Garching (Germany)MPE, Garching (Germany)

PNSensor, Munich (Germany)PNSensor, Munich (Germany)

Politecnico, Milan (Italy)Politecnico, Milan (Italy)

IMEP, Vienna (Austria)IMEP, Vienna (Austria)

IFIN-HH, Bucharest (Romania)IFIN-HH, Bucharest (Romania)

Conclusions

Results obtained with DEAR and evaluations done for Results obtained with DEAR and evaluations done for SIDDHARTA show that DASIDDHARTA show that DANE represents an ideal NE represents an ideal machine for hadronic atoms researchmachine for hadronic atoms research

Continuing tests on detectors to obtain best performance Continuing tests on detectors to obtain best performance prototype, compatible with a large area setup.prototype, compatible with a large area setup.

Finalizing the design of the new experimental setup:Finalizing the design of the new experimental setup:front-end electronicsfront-end electronics, mechanics, cryogenics, vacuummechanics, cryogenics, vacuum

20062006Assembly on DAAssembly on DANENE and data takingdata taking