18/05/06 P. Nedelec - 4th Air Fluorescence Workshop

Measurements of FLY with MACFLY

2

Measurement of Air Cerenkov and Fluorescence Light Yield

http://wwwlapp.in2p3.fr/MACFLY/

LAPP (France): Pierre COLIN, Patrick NEDELEC;LIP (Portugal): Antonio ONOFRE;JINR (Russia): Leonid TKATCHEV, Artem CHUKANOV, Basar SABIROV, Yuri NEFEDOV, Sergei POROKHOVOI, Dmitry NAUMOV.

Collaboration:

3

Original Goals

To Measure Air FLY variations as a function of atmospheric conditions:

Reproduce and study in laboratory the light emitted

by an “extensive air shower” (EAS)

15 km

2 km

EAS

Temperature Pressure Humidity

- 60°C

10°C

100 hPa

800 hPa

0 %

1 %

Alt

itu

de

(km

)

4MACFLY project = 2 devices

Vacuum pump

N2 Air

Ar

O3

Beam:- β Source- CERN- JINR

PMT

Preshower

Gauge : P,T,H2O

H2O

shower

Gas system

MACFLY 1(for beam)

MACFLY 2(for shower)

5

MF1: a reference device

• Single track events device– Light, compact, movable (plane?),…

• Used both– @ Lab (quiet) – on Test Beam (noisy)

• Measure:– Air/N2FLY– Cherenkov contribution

• Used for comparison with– Other experiments– MF2

6Macfly 1 @ LaboratoryPompe à

vide

90Sr β Source

PMT1

PMT2Electrons

beam

Scintillator

PM Trigger

Radioactive source

Sr90

Optic fibres

Pressure sensor

Main tankTemperature

sensor

Input/ouput of gas

PMT

Vacuum pump

Trigger PMT

7

MF1 cut view

EMI

9820

QA

EMI9820QA

PMT EMI 9820QAQuartz Window

Filters Quartz Lens

Mirror : ~98%(multi-layers)

Light Guide

Electron beam

15 cm

Macfly 1 optical system

EMI9820QA

5 cm

Filter

Filters Transmittance (Schott BG3 and GG385)

8

MF2: looking for real showers

• A “From single track to showers” device– Heavy, Big, Fix ,…

• Used:– Only on Test Beam Line

• Measure:

– Air/N2 FLY induced by a e- shower (10-50 GeV)

– From 0 to Xmax radiation length

• Used to:– Perform original measurements– for comparison with Monte Carlo prg (G4,…)

9

Macfly 2 (MF2)Ø

96 cm

146 cm

Volume : ~1m3Input/Output of gas system

CERN Beam

PMT

Sensors (P,T)

Cooper target(Preshower)

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MF2 working process

EM

I

EMI

Black surface

Ø10 cm

Light guide

Filters

Preshower

Electromagnetic Shower

Preshower system:

PMT EMI 9820QAQuartz Window

Electron beam

Stack of copper disks (Thickness :1cm)

Lead shield

11

Measurement campaigns

> At JINR ? : (MF1)– Microtron(12 MeV) and Phasotron (170 MeV) – Pressure and temperature dependencies

> In Lab : (MF1)– Radioactive source (1.5 MeV electron)– Pressure dependence

> At CERN : (MF1+MF2)– SPS test Beam (5-100 GeV e-, μ-, π-)– Pressure dependence: ; Temp., H2O: – Shower age dependence (MF2)

Too noisy! Then a Fire !!!

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MACFLY set up overview at CERN

Macfly 2

Delay chamber

MF2

Trigger TriggerMF1

Thermal Box

Small Trigger

MF1 in its thermal box

Pumping system

Large Trigger

Delay chamber

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Macfly Data

Event by event acquisition

PMT signal read by a QADC (Gate=100ns)

Very Low signal: mean=0.01photoelectron

Expected FLY ~ 4 ph/m

~106 triggers/run (1/2 data+1/2 Bgd)

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Delay chamber

MF2

Trigger TriggerMF1

Thermal Box

Macfly Data selection

Centered events

15

MacFly: Fluo. Signal extraction

DL = FLY x εMF + CDL + Bgd

PMT Detected Light (fit method)

Cherenkov Detected Light

(Geant4 simulation)

Background (Vacuum

measurement)

Fluorescence Light Yield (in photons)

Detector efficiency

(Calibration)

FLY/E = FLY / EdepDeposed Energy(Geant4 Simulation)

16

Macfly Data

Detected Light: PMT spectrum fit Method

Pedestal : (~99% of events)

Single photoelectron(~1% of event)

2 photoelectrons

DL = FLY x εMF + CDL + Bgd

17

MacFly: Geant4 Simulation

Geometrical Acceptance(Optical Properties of surfaces were previously measured)

εMF = Accgeo x QEPMT

DL = FLY x εMF + CDL + Bgd

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MacFly: Geant4 Simulation

DL = FLY x εMF + CDL + Bgd

Cherenkov Light: compare simulation with data

LensesCerenkovcatcher

e-

Cherenkov light in MF1

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MacFly: data

Background:

DL = FLY x εMF + CDL + Bgd

• Well measured events– Random triggers (@lab)– Off-spill triggers (@beam)– Vacuum On-spill triggers (@beam)

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MacFly: Geant4 Simulation

Radiation length (#X0) 0 disc

1 disc

3 disc

5 disc

7 disc10 disc

Pre-Shower

Deposed Energy in MF2

Deposed Energy:

FLY/E = FLY / Edep

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Detected Light Composition

DL(Macfly data)

CDL(Simulation)

Bgd(Measurement)

FDLFluorescence detected light

MF1 : 50 GeV e- in airMF1 : 50 GeV e- in air MF1 : 50 GeV e- in N2MF1 : 50 GeV e- in N2

MF1 : 1.5 MeV e- in airMF1 : 1.5 MeV e- in air MF2 : 50GeV Shower in airMF2 : 50GeV Shower in air

22Systematic errors of MF1

Error Sources

MF1 (Dry Air)

CERN Lab.

QE of PMT 10% 10%

Geo. Acc. 8.2% 7.5%

DL Recon. 3.5% 4%

CDL Simu. 2% 0%

Bgd Meas. 2% 1%

FLY : 13.7% 13.2%Edep 1% 1%

FLY/E : 13.7% 13.2%

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MF1 result: Pressure dependence

We create a model of air FLY proportional to deposed energy which fit all Macfly data.

(Dry air and pure Nitrogen)

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MF1 result: Energy dependence

Reference point : Dry air at 1atm. & 23ºC: FLY/E = 18 ph/MeVReference point : Dry air at 1atm. & 23ºC: FLY/E = 18 ph/MeV

dEdX: Berger-Seltzer formula All experiments are coherent

25

Absolute measurement

Reference point : Dry air at 1atm. & 23ºC : FLY/E = 18 ph/MeVReference point : Dry air at 1atm. & 23ºC : FLY/E = 18 ph/MeV

dEdX: Berger-Seltzer formula All experiments are coherent

Error< 10% ?

26

MF2 result: Shower age dependence

500 hPa data

100 hPa data

PDG model of shower development

Air FLY follows the shower development !Air FLY follows the shower development !

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MF2: Air FLY deposed Energy

FLY/Edep and pressure variations independent of the excitation source

FLY/Edep and pressure variations independent of the excitation source

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Conclusion

Measurements done: P. Colin thesis Dry air and pure Nitrogen fluorescence 1.5 MeV, 20 GeV and 50 GeV incident electron Lab. measurement of air Shower FLY Pressure and Shower age dependencies

Fluorescence model: Air FLY Edep Fitted on Macfly data Compatible with previous exp. (<10%)

Back to the future: PMT calibration Temperature dependence Papers in preparation

Systematic down to: ~10%