charmonium physics with panda

Verification of a Novel Calorimeter Concept for

Studies of Charmonium States

Elmaddin Guliyev

Thesis defense date October 31

Promotor: Prof. dr. H. Löhner Copromotor: Dr. M. Kavatsyuk

● Motivation of charm physics● Experiment with antiprotons: PANDA ● PANDA Electromagnetic Calorimeter

● Signal analysis for PANDA EMC

● Performance studiesTime and energy resolution

Sampling ADC optimization

● On-line signal processing

● Physics evaluation of PANDA EMC

● Summary

The origin of hadron mass

More than 99% of the visible Universe is made of protons and neutrons (u, d quarks)

Proton/neutron are much heavier than their quark and gluon constituents!

Expect an answer from systems with heavy quarks: Charm

18.10.11 E.Guliyev, Verification of a Novel Calorimeter Concept 2

Strong coupling

3 18.10.11 E.Guliyev, Verification of a Novel Calorimeter Concept

Asymptotic freedom:

Quantum Chromodynamics (QCD) is well tested at highenergies: strong coupling constant α

s

is small.

Confinement:

Large distance →formation of hadrons:strong coupling constant α

s

increases drastically.

Charmonium

Mesons containing a charm quark and anti-charm quark.

Spectrum of charmonium states:testing ground for the nature of the strong interaction.


Charmonium

Orbital momentum

and spin dependence

What we can learn

about strong interaction?

Exa

mpl

e




antiProton ANnihilations at DarmstadtCharmonium

How we can produce such systems:

1. e-e+ collisions

2. two photon collisions

3. interactions p p̄

All possible charmonium states can be directly populated


antiProton ANnihilations at DarmstadtExotic states

Physics program:

Tetraquark meson

Hybrid states

Molecular states: X(3872) ?


Small cross sections require high luminosity!

antiProton ANnihilations at DarmstadtHigh Energy Storage Ring (HESR) for antiprotons


PANDAtarget

electron cooling

stochastic cooling

High luminosity 2·1032cm-2 s-1

High momentum resolution σp

/ p = 10-5

50 m

antiProton ANnihilations at DarmstadtCharmonium




Example:h

c(1P

1) → η

c + γ → η + 0 + 0 + γ → 7 γ

ηc(1S

0)→ γ + γ → 2 γ

J/ψ→ e+ + e-

Required: Electromagnetic Calorimeter!

antiProton ANnihilations at DArmstadt PANDA Detector


physics program requires: have a good - particle identification - momentum resolution for γ, e, μ, π, K and p - vertex reconstructionexcellent calorimetry

cover 4π solid angle,high luminosity → operation with high rates (2·107 annihilations/s)

antiProton ANnihilations at DArmstadt


Electromagnetic Calorimeter (EMC)

detection of photons, electrons, and positrons4π coverage

three parts - Barrel, Forward and Backward Endcaps

wide dynamic range: 10 MeV up to 10 GeV

low threshold ~ 1 MeV

Have a high

Energy Resolution

Time Resolution

Position Resolution

antiProton ANnihilations at DArmstadt


EMC detector material and photo sensor

PWO (PbWO4) scintillatorDensity 8.29 g/cm3 Light yield (-250C) 500 ph/MeV(NaI(Tl): 38000 ph/MeV)Decay time ~ 6 – 30 nsSize ~ 20 X 20 X 200 mm3

17000 PWO crystals

Large Area Avalanche Photodiode (LAAPD)Size 7 X 14 mm2 2 LAAPD per crystalPhotograph of two standard (5 X 5 mm2) APDs one square LAAPD (10 X 10 cm2) one rectangular (7 X 14 mm2) LAAPD


The preamplifier

antiProton Annihilations at DArmstadt

Low Noise low Power (LNP), Basel Univ. design one-channel, single-range, discrete-component,size 18 X 47 mm2,

no-shaping.

Preamplifier pulse

25 µs decay time

APFEL ASIC, GSI design, two-channel,dual-range, 250 ns shaping.

Developed by T.Poelman

ASIC pulse


antiProton ANnihilations at DarmstadtSignal analysis for PANDA EMC

High annihilation rate – 20 MHz

event rate 500 kHz for single detector

efficient event selection based on physics(e.g. secondary vertex, momentum of reconstructed particles.)

New approach for data acquisition (DAQ): “trigger-less”


Signal analysis for PANDA EMCImplementation of trigger-less DAQ

To realize the trigger-less DAQ, each sub-detector mustindependently: detect hits, report to DAQ.

Realized bySampling ADC (SADC):

Analog output of preamplifieris periodically measured.

Obtained data must be processed on-line.

10 ns

sampling of preamplifier signal


Signal analysis for PANDA EMCLayout of readout electronics chain for PANDA EMC

To build the trigger-less readout: preamplifier signals digitized by SADC,

processed on-line by Field Programmable Gate Array (FPGA):

Many logic cells with programmable connections→ Developed the program logic,

Prepared algorithm for implementation on commercial SADC.


Signal analysis for PANDA EMC Sampling ADC

commercial STRUCK SIS3302 Module

8 channel

100 MHz sampling rate

16-bit resolution

5 FPGA

- verify the performance for physics analysis

- develop data-processing algorithm

- find optimal parameters for digitizer

For on-line pulse processing

Performance studiesExperimental setups

single crystal setup:EMC Prototype setup

Studied: Performance of Time and Energy resolution

Optimization of Sampling procedure

Implementations in FPGA


array of 60 crystalsCarbon fibercontainers

4 crystals packed in reflective material


Signal analysis for PANDA EMC

Input (SADC data)Digital Filter

(shape+noise reduction) Pulse detection

Timing method Time

Energy

Signal analysis for PANDA EMCData-processing algorithm

time-stamp

ener

gy

difference of time-stamps


amplitude distribution

raw

filtered

digital Constant Fraction Timing

rms = 0.4 ns

M.Kavatsyuk,E.Guliyev et al., NIM A 648, 77 (2011)

21

Performance studiesTiming performance

from time coincidences with LED light pulser

Influence of noise level

Sing

le c

ryst

al se

tup

18.10.11 E.Guliyev, Verification of a Novel Calorimeter Concept

∆tRMS = rmscoincidence time

/ √2.

Cosmic muon energy

equivalent (20 MeV)

We can reach resolution well below 1 ns

Performance studiesTiming performance

Timing performance with LED light pulser, CFT linearity

Sing

le c

ryst

al se

tup

Linearity between analog (TDC) and digital CFT method

Digital CFT method works properly


Performance studies Timing performance with EMC Prototype

3X3

crys

tal a

rray

setu

p

For energy deposition higher than 80 MeV: time resolution less than 1 ns

Sufficient to complete PANDA mission!


High energy photon beam:

beam directed between two crystals

Performance studiesEnergy resolution study with EMC Prototype

3X3

crys

tal a

rray

Incident photon energy:E = 0.685 GeV

Epeak

= 0.671 GeV

λ = 0.032 GeV

σ =

0.02

4 G

eV

Photon response for 3X3 crystalarray for different incidentphoton energies.


Asymmetric response curve → σ for energy resolution

Performance studiesEnergy resolution study with EMC Prototype

3X3

crys

tal a

rray

σ/E = a + b/√E(GeV)

a (50 MHz) = 0.35 % b (50 MHz) = 1.97 %

a (100 MHz) = 0.42 % b (100 MHz) = 2.04 %

a (analog) = 0.31 % b (analog) = 2.44 %

The energy resolution can compete with analog readout;


FPGA ImplementationSi

ngle

cry

stal

setu

p

(Field Programmable Gate Array)

On-line extraction of energy and time information,

Applicable for different pulse shapes,

Data processing algorithm implemented in VHDL code

by KVI electronics engineer P.J.J. Lemmens

Implementation tested with

LED light pulser on XILINX development board

LED light pulser and cosmic muons on STRUCK SADC


E.Guliyev, M.Kavatsyuk et al., NIM A (2011) accepted


ngle

cry

stal

setu

p


Test with XILINX development board and SADC


SADC data

TimeEnergyDebug

SADC datafrom crystal setup

binary switch

FPGA ImplementationBlock diagram of signal processing in FPGA

Sing

le c

ryst

al se

tup


Fast, compact, efficient block structure

Filter 1:shaping

Filter 2:shaping

Filter 3:noise reduction

Event selection

FPGA ImplementationBlock diagram of signal processing in FPGA

Sing

le c

ryst

al se

tup


In ASIC preamplifier case Filter 1 and Filter 2 are bypassed

Filter 1:shaping

Filter 2:shaping

Filter 3:noise reduction

Event selection

FPGA Implementation Debug mode

To follow any intermediate step→ check proper operation,

fast processing, typ. 80 ns

Sing

le c

ryst

al se

tup


Raw trace Filtered traces

CFT trace


ngle

cry

stal

setu

p


The correlation coefficient is 99.9% between off-line and FPGA processing

LED light pulser test for XILINX development board

Energy resolution Time resolution



ngle

cry

stal

setu

p


LED light pulser test for SADC

The correlation coefficient 99.9% between off-line and

on-line pulse processing

The implementation is working as expected !

Energy resolution Time resolution


Physics Evaluation Validation of simulation: Experiment vs. Simulation

Sing

le p

hoto

n fir

e th

e 3X

3 cr

ysta

l arr

ay

200 MeV single photons

0.3 MeV noise level

1 MeV single

crystal threshold

Good agreement!


Physics EvaluationPA

ND

A E

MC

res

pons

e ab

ility

hc(1P

1) → η

c + γ → η + 0 + 0 + γ → 7 γ

Has high branching ratio

54.3 ± 6.7 ± 5.2%

Final state 7 γ, only EMC response

Simulated different noise in electronics

and different detector thresholds

High electronic noise ==> worse resolution !

digital pulse filtering superior

to analog readout


σ

Wid

th (M

eV)

Physics EvaluationThreshold dependence

Lower noise level → lower thresholds

Lower cluster threshold → higher photon statistics, smaller width, higher efficiency

PAN

DA

EM

C r

espo

nse

abili

ty


achieved with digital filtering

WHAT HAVE WE ACHIEVED?

First essential step in constructing a trigger-less DAQ:● Developed on-line feature-extraction algorithm.● Achieved time and energy resolution sufficient to complete

the physics program: ● Low noise level: 0.3 MeV.● Energy resolution: 2.4% at 1 GeV.● Time resolution: 1 ns at 0.08 GeV energy deposition.

● Optimized SADC parameters for best performance: Sampling speed, bit resolution, power consumption.

● Demonstrated importance of optimization for physics performance.


SUMMARY

1. Digital readout electronics developed. 2. Novel calorimeter concept verified

using photon beams. 3. Promising results achieved: energy, time resolution;

fast on-line processing.

4. First step towards trigger-less DAQ chain.

Thanks to Peter Lemmens for electronics support!

18.10.11 E.Guliyev, Verification of a Novel Calorimeter Concept

B1

BackUp Slides

18.10.11 E.Guliyev, Verification of a Novel Calorimeter Concept for Studies of Charmonium States

Tim

ing

stud

y

Time resolution for different case – huge discrepancy LED and particle measurement

B2

BackUp Slides


Tim

ing

stud

y

Preamplifier output is different for same condition, temperature, energy dep. etc

WHY?

B2

BackUp Slides


Tim

ing

stud

y

GEANT 4 simulation for 100 MeV photon

Hits the end face of PWO crystal

Distribution of arrival time of optical photons

for different decay time:

15 ns (top panel)

30 ns (bottom panel)

B3

BackUp Slides


Tim

ing

stud

y

Sum of number of photons as a function of arrival time of photons

B4

BackUp Slides


Tim

ing

stud

y

Experimental study of decay time

(or pulse rise time)

Influence to time resolution

Specifications To optimize the SADC parameter

Sing

le c

ryst

al se

tup

with

ion

beam

50 MHz sampling rate is sufficient to obtain energy and time resolution.

18.10.11 E.Guliyev, Verification of a Novel Calorimeter Concept B5


ngle

cry

stal

setu

p


Comparison of pulse amplitudes obtained as MWD amplitude m[soft] and m[fpga] for the softwareanalysis and the FPGA processing, respectively. According to the cosmic-ray calibration, the loweramplitude corresponds to 80 MeV and the higher one to 390 MeV. The correlation coefficient is99.9%.

Off-line On-line


ngle

cry

stal

setu

p

On-line cosmic muon measurement:

raw spectrum and coincidence spectrum.

Time stamp difference distribution for off-line

and on-line pulse processing.


charmonium physics with panda

Education

novel calorimeter concept8

novel calorimeter concept10

novel calorimeter concept13

antiproton annihilations

spectrum of charmonium

darmstadt panda detectorcover

panda emcto

possible charmonium