The trigger system for the AMADEUS experiment

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The trigger system for the AMADEUS experiment
Alessandro Scordo

• Trento, ECT Workshop 2009
• October 14, 2009

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Antikaon Matter At DA?NE Experiments with
Unraveling Spectroscopy
AMADEUS collaboration 116 scientists from 14
Countries and 34 Institutes lnf.infn.it/esperime
nti/siddharta And LNF-07/24(IR) Report on
lnf.infn.it web-page (Library)
For the scientific case of AMADEUS
experiment J. Zmeskal, The AMADEUS
experiment, Thu 15 october
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Summary

• The idea of the AMADEUS trigger
• MPPC characterization and lab tests
• Monte Carlo simulation for lab tests
• and DAFNE beam
• Data taking on DAFNE results and
• future plans

VISIT ON THURSDAY AT ITC-irtst
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• Study of the hadronic interactions of K- in
  light nuclei at DAFNE

AMADEUS First dedicated full-acceptance study
KLOE K- hadronic interactions in the KLOE data
DAFNE
KLOE
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The idea of the AMADEUS trigger
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Letter of Intend Day-1 proposal
Study of deeply bound kaonic nuclear states at
DA?NE2 Low energy
kaon-nuclei Interaction studies
- The main aim of AMADEUS is to confirm or deny
the existance of Kaonic Clusters, - EXTENDED
PROGRAM Low-energy interactions, cross sections
in light nuclei, decay of resonance states and
exotic channels in nuclear medium will be studied
K-ppn
?p
?np
S-pp
S0d
S0np

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The experimental setup of AMADEUS

• The AMADEUS setup will be implemented in the 50
  cm. gap in KLOE DC around the beam pipe
• Target ( A gaseous He target for a first phase of
  study)
• Trigger (1 or 2 layers of ScFi surrounding the
  interaction point)
• Inner tracker (eventually, a first tracking stage
  before the DC)

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Trigger system

• Cilindrical layer of scintillating fibers
  surrounding the beam pipe to trigger K K- in
  opposite directions
• Single or double layer
• Readout to be done by MPPC (Multi Pixel Photon
  Counter)

In this case possibility of perform tracking as
well X-Y measurement with high granularity layers
target
K-
e
e-
?
Trigger system ScFi MPPC readout
K
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Trigger system
Using scintillating fibers MPPC
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MPPC characterization and lab tests
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MPPC tests

• Array of single Geiger Mode APD.
• Photon counting depending on the PIXEL size
• Ideal for
• ScFi coupling
• High granularity detector
• Time resolution below 1 ns
• Insensitive to strong magnetic fields
• High gain (gt106) and quantum efficiency

Different options available in the market,
becoming a standard light readout system
(Hamamatsu, Photonique, etc) MPPC Hamamatsu
S10362-11-050U efective area 1mm2 400 pixel ?
270-900 nm working biases ? 70 V .
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MPPC tests New electronics

• - The Geiger mode of MPPC makes gain extremely
  dependent of applied Vbias
• A characterization of this dependency based on
  the peak distance of intrinsic noise
• For a good behavior stability in the applied
  voltage with great precision is needed for every
  single detector.

• Electronics New NIM modules providing
• Variable Vbias for 5 channels with a stability
  for
• nominal voltages below 10 mV
• 2 output / channel
• -Amplified (x50-x100) signal
• -Discriminated signal (variable threshold)
• Designed by G. Corradi, D. Tagnani, C. Paglia

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ScFi MPPC tests
New mechanical support for 5 ScFi read from both
sides 10 MPPC readout card

• Instrumented fibers
• Saint Gobain BCF- 10 single cladding
• Emission peak 432 nm
• Decay time 2,7 ns
• 1/e 2.2 m
• 4000 ph./MeV

Precission support for efficiencies studies
November, 2008
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Characterizing MPPC Dark Count
Setting a threshold to 0.5 or 1.5
photoelectrons, dark count rates have been
evaluated
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Characterizing MPPC Dark Count
Detectors were cooled down in order to
study their behaviour with temperature
variations. A scan of the 1 p.e peak rate is
reported
Cooling system
Peltier cell
Dark count 1 p.e signal is reduced by a factor
20!
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Characterizing MPPC reading scintillating fibers
A scintillating fiber is activated by a beta
Sr90 source Both ends are coupled to detectors
one is used as trigger
Setting the threshold for the MPPC used as
trigger, most part of dark count is
eliminated. In this way spectra due only to the
source can be observed
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Characterizing MPPC reading scintillating fibers
Studying rates with and without the beta source,
it turned out that starting from the 4th p.e.
Peak, dark count contribute is negligible This
means that non cooling is needed in this
case!!!! With 4 p.e. threshold, main peaks of
Sr90 are of 4 and 5 photoelectrons.
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MC simulations
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Montecarlo simulations what are we expecting?
Some geant3 simulations were done in order to
understand how many p.e. should be left by Kaons
in DAFNE First, a simulation af a fiberSr90
source was done, in order to compare it
with experimental data
Initial momentum of electrons
Mean 150 KeV
Momentum spectrum of Sr90
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Montecarlo simulations what are we expecting?
Comparing with experimental data Mean energy
loss 150 KeV
600 photons (4000
ph/MeV) Nominal trapping efficiency 4
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photons Attenuation length 2.2 m (1/e)
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photons (30 cm) Q.D.E. 50
11 photons Reading 1 size
5/6 photons
Consistent with lab tests
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Y
K- track
R2.95 cm
X
Beam Pipe 300 µm Alluminium
376 fibers
Double cladding 3 of r
r0.5mm
Setup consists in 2 layers of 70 cm scintillating
fibers BCF-10 multicladding. Beam Pipe is an
alluminium tube with radius r2.95 cm and 300 µm
thickness.
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Momentum distribution taken from Kloe MC
(MeV)
In each layer energy loss by Kaons is 2
MeV This means a factor 13 more than Sr90 e-
wich becomes a factor 10 including attenuation
length for 70 cm
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Data taking on DAFNE
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Trigger system tests installation at DAFNE
SIDDHARTA setup
DAFNE beam pipe
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Trigger system tests installation at DAFNE
SIDDHARTA setup
DAFNE beam pipe
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Trigger system tests installation at DAFNE
Installation of AMADEUS trigger test setup in
DAFNE 2009
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Trigger system tests installation at DAFNE
Kaon (?) peak around 80 photo-e X 10 from e-
and d.c. as expected by simulation
Installation of AMADEUS trigger test setup in
DAFNE 22-24 January 2009
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Trigger system tests installation at DAFNE

• Time difference between MIPs and Kaons is 1 ns
• Time difference in AMADEUS will be much less (
  300/400 ps) because trigger will be placed just
  around the beam pipe
• High timing resolution is needed!!!!
• TDC spectra are needed to understand behaviour of
  MIPs and Kaons on fibers
• SIDDHARTA Kaon Monitor can be used as reference

New data taking on DAFNE with new DAQ (including
KM)
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Trigger system tests installation at DAFNE

• KM scintillator at 6 cm from Interaction point
• Fibers 5 cm below the lower scintillator
• RF/2 and KM coincidence as gate and stop
• Pure KM signal also collected
• High thresholds for MPPC (above d.c.)

MIPs of high energy tail comes from E.M. Shower
wich occurs in lead bricks placed as shielding
just before interaction region This particles
pass with low angle in KM (losing more energy)
but not in fibers
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Trigger system tests installation at DAFNE
Kaon Monitor TDC (upper/lower coincidence) TDC
working in Common Start (RF/2) Single peak
resolution 100 ps MIP/K separation 1 ns
3 ns
MPPC tdc spectra TDC working in Common Stop
(RF/2) Single peak resolution 300 ps
Missing MIPs
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Trigger system tests installation at DAFNE
Black MPPC total ADC spectrum Red MPPC ADC when
event on KM Green MPPC ADC when Kaons in
KM Blue MPPC ADC when MIPs in KM
Time correlation between MPPC and KM
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Trigger system tests installation at DAFNE
KM tdc when events on fiber
MPPC tdc when Kaons in KM
KM total
MPPC tdc when MIPs in KM
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Trigger system tests installation at DAFNE
KM tdc when events on fiber
MPPC tdc when Kaons in KM
FINAL TEST tdc spectra WITHOUT Kaon Monitor
signals as reference
KM total
MPPC tdc when MIPs in KM
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Conclusions
AMADEUS

• Trigger is a crucial point and some
• preliminary indications are coming
• from test setup in DAFNE
• Achieved best single peak resolution around 300
  ps
• Final test of feasibility is undergoing
• Simulation of K and MIPS on test setup are
  undergoing

_at_ DAFNE

• First publications
• A. Scordo et al. Silicon PhotoMultipliers(SiPM)
  for the AMADEUS trigger system
• Proc. XLVII International Winter Meeting on
  Nuclear Physics Bormio(Italy), 26-30 January
  2009
• M. Bazzi et al. Scintillating fibers read by
  Multi Pixel Photon Counter as trigger system for
  AMADEUS experiment at DAFNE AMADEUS technical
  note IR-1 29/09/2009