Multi Pixel Photon Counters (MPPC)

and Scintillating Fibers (Sci-Fi)

as a trigger system for the

AMADEUS experiment

Alessandro Scordo (L.N.F.) (in behalf of AMADEUS experiment)

23° Indian-Summer School of Physics & 6° HADES Summer School 2011

The AMADEUS experiment: a brief introduction

Trigger system requirements

MPPC working principle and status of art

10 channels prototype and MPPC characterization

Results of tests on DAFNE

New electronics and 64 channels prototype

Tests on hadronic beam

Conclusions

Contents

DAΦNE

KLOE

The AMADEUS experiment: a brief

introduction

- 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

The AMADEUS experiment: a brief

introductionDeeply Bound Kaonic Nuclear StatesFirst suggested by S.Wycech (1986)

Y.Akaishi and T. Yamazaki

(Phys. Rev. C65 (2002) 044005)

“Nuclear bound states in light nuclei”

Normal Nuclear binding energy parameters:

Ebind ~ 20 MeVG ~ 100 MeV

DBKNS binding energy parameters:

Ebind ~ 100 MeVG ~ 30 MeV

K- + 4He reaction(3-barionic state)

New kind of matter withastrophysical implications(Neutron stars, prof. Heuser talk)

The AMADEUS experiment: a brief

introduction

Target: A gaseous He target for

a first phase of study

First 4p fully dedicated setup!

The AMADEUS experiment: a brief

introduction

The AMADEUS experiment: a brief

introduction

Trigger system

requirements

Multi Pixel Photon Counters (MPPC)

1) Small dimensions2) Working in magnetic field3) Working at room temperature4) Very good time resolution (s ~ 300 ps)5) High efficiency

MPPC : working principleP-N junction array working in

Geiger mode (micropixel)

Output signal is the sum of

all the micropixels

Each micropixel gives a high

gain signal (105 – 106)

indipendent of the number

of incident photons

and has a fixed amplitude

(binary mode)

First prototype and MPPC

characterization

Is cooling

needed ?

A scintillating fiber is

activated

by a beta Sr90 source

Both ends are coupled to

detectors;

one is used as trigger

First prototype and MPPC

characterization

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!!!!

Montecarlo simulations: what are we expecting?Momentum distribution of kaons is taken from Kloe Monte Carlo

BCF-10 1mm

diameter

Kaons are expected to leave almost a factor 7

more energy

than MIP electrons

GEANT3 simulation

22-24 January 2009

Results of tests on DAФNE

Results of tests on DAФNE

MIPs coming from the I.P. are below the KM threshold

• KM scintillator at 6 cm from Interaction Point• Fibers 5 cm below the lowest scintillator• RF/2 and KM coincidence as DAQ trigger• Pure KM signal also collected

Results of tests on DAФNE

Kaon Monitor TDC (upper/lower coincidence)

Single peak resolution Is ~ 100 ps

MIP/K separation ~ 1 ns

MPPC tdc spectra

Single peak resolution Is ~ 300 ps

Missing MIPs

Results of tests on DAФNE

K-

MIPs

New electronics and 64 channels prototype32 Sci-Fi read at both sides

2 indipendent double layers with adjustable angle

Amplification of a factor 10

64 Constant Fraction Discr.

Logic OR of all detectors

Single particle conditon

(to be further checked)

Scintillator 1 Scintillator3&2

1

2 4

3

Tests on hadronic beam pM-1 beam at Paul Scherrer Institute (PSI, Zurich)

,p m,e-,p beam(similar to DAFNE situation)

Double anular setup

DAQ trigger:Sc1&Sc2

Common cuts for the whole analysis

Cut fot T > 31.0 CProtons

MIPs

Tests on hadronic beam

Perfect correlation and coupling Sc1 is used as reference

Left

Right

Tests on hadronic beam

Single layer efficiencyDouble layer efficiency

Tests on hadronic beam: efficiency

Fiber 5: eff = 99 %

Fiber 6 : eff = 98,4 %

73% 92%

70% 90%

Tests on hadronic beam

Beam profileGeometrical correlation

2,4% 5,2%

6,5% 2%

4,6% 2%

1% 0,06%

Fired fibers of layer 4 if fiber i of layer 4 is fired

Tests on hadronic beam: cross talk

Conclusions…

Temperature feedback circuit implementationNew efficiency measurements with scintillatorsNew tests in DAFNENew ideas and applications for this nice setup

…and future plans

1) Small dimensions 2) Working in magnetic field3) Working at room temperature4) Very good time resolution (s ~ 300 ps)5) High efficiency …

Spare slides

Luminescence of carriers can also

be absorbed by another pixel

giving a noise signal

Thermally generated electrons can

activate the avalanche process in some

pixel, with a high rate of 105-106 Hz (dark

current)

The main contribute is a peak

corresponding to

1 pixel (photoeletron)

MPPC : working principle

First prototype and MPPC

characterizationPre-Amplifiers (X 100)

SiPM (HAMAMATSU U50) (400 pixels)Operating voltage ~70V

Scintillating fibersBicron BCF-10 (blue)

5 Channles HVpower supply(stability better than10 mV)

Sr90 beta source (37 MBq)

First prototype and MPPC

characterization

Black spectra are the trigger-used MPPC

Red spectra are the signal outputs of the NON trigger MPPC

Peak with mostcounts: 5 p.e. (15%)

Threshold at 5 p.e.

New electronics and 64 channels prototype

s ~ 40 ps s ~ 80 ps

Direct laser on MPPC MPPC + Sci-Fi

Fiber

Laser

HV HV

MPPC

RF

Preamp

Coincidence

TDC

RF/n RF=90 MHz (≈ RF/4)n ≈ 10000

New electronics and 64 channels prototype

s ~ 200 ps

No jitter from photon generation(to be considered)

Tests on hadronic beam: “relative” efficiency

Fiber 5: eff = 27,3 %

Fiber 6: eff = 30,1 %

In the case of non parallel double layers the geometrical efficiency is drastically reduced

Tests on hadronic beam: “relative” efficiency

Fiber 5: eff = 27,3 %

Fiber 6: eff = 30,1 %

In the case of non parallel double layers the geometrical efficiency is drastically reduced

Tests on hadronic beam: “relative” efficiency

Proton events = 6580

Proton on fibers = 1772

Nhits on fibers > 5 = 29 (1,6%)

Single particle configuration !