VHEPU-05 13-Mar-2005 P. N édélec - LAPP Air Fluorescence Light Yield Measurements Summary of the...

13-Mar-2005 P. Nédélec - LAPP VHEPU-05

Air Fluorescence Light Yield Measurements

Summary of the

IWFM05 Workshop

http://lappweb.in2p3.fr/IWFM05/

Thanks to IWFM05 speakers

http://lappweb.in2p3.fr/IWFM05/


Purpose Understand (better) and Calibrate the Air

Fluorescence Light Yield (FLY) Estimate the quality of the “air” as a

scintillator Understand experimental uncertainties

Hires – Agasa controversy


Who is interested?

• HiRes (and AGASA)• Auger• EUSO, TUS, KLYPVE,

OWL,…• Telescope Array


Extensive Air Shower

Interaction UHECR/atmosphere

Charged tracks on groung (AGASA, AUGER,TA,…)

Air Fluorescence (HiRes, AUGER,TA, EUSO,TUS,…)

+Čerenkov


Shower & Atmosphere properties

Shower Max2-13 km (0o-80o)

FLY should varies with:•Pressure•Temperature•Components (H2O,…)

0 0.5 1 1.5 2

H2O fraction (%)

0 200 400 600 800 1000 1200

Pressure (hPa)

0

5

10

15

20

25

200 210 220 230 240 250 260 270 280 290 300

Temperature (K)

Alt

itu

de

(km

)

-50 +20 oC 0.2 1 atm


Bremsstrahlung

N2

N2

N2

N2

N2

N2

N2

N2

N2

N2

N2

N2

O2

N2

N2

N2

N2O2

O2

O2

N2

Ar

N2N2N2

N2

N2

N2

N2N2

O2

O2

e-(high energy)

N2

N2

O2

Ar

N2

N+2

N2

Electron induced Air excitation

N+2

N+2

Ionisation

N+2

γ

N+2

N+2

O-2

N2 and N2+

excitation


N 2

N2

N2

N2N2

N2

Air De-excitation

N2+

Fluorescence:UV

UV UV light emission

Collision:Increase of temperature

No UV light produced

Competition between different processes:

Decay Time / Collision Time

N2+

N2+ N2N 2

+

N2


Wave length (nm)

Fluorescence Light Yield Spectrum

Between 300 et 400 nmThe Space Window

Incertainties on FLY measurements: 30%

Davidson et O’Neil (1964)Bunner (1967)


What to measure?

Air & N2 FLY as a function of:

Reproduce & study in laboratory the light induced by

an atmospheric shower

• Pression (0 to 1 atm )• Temperature (-50 → 20 oC)

• Air composition (O2, Ar…) • Impurities (humidity, aerosol…)• Particule energy• Particule density• Particule nature (e-,,, , p…)

• Shower age (#X0)

• Cherenkov contribution• Lifetimes

N2 for ref.comparison


History - References• A.N. Bunner, PhD thesis, Cornell, 1967:

– “Cosmic Rays detection by Atmospheric . Fluorescence”– Nitrogen fluorescence spectrum between 300 and 400nm– Compilation– Error ~ 30 % on yield at each

• H. Brunet, PhD thesis, Toulouse,1973:– “Destruction des états C3u de N2 dans l’azote pur et

mélange avec O2, H2O, CO2,CH4”

– Rediscovered at Bad Liebenzell (second workshop)• Kakimoto et al. (1995):

– measurement of total yield between 300 and 400 nm– three lines (337 nm, 357 nm, 391 nm)– Error > 10 %


A New Field emerged

Goal: understand the fluorescence yield to better than 10 %


Name Particle source Number of particles

Particle energy

Nagano* 90Sr β 0.85 MeV

Airlight 90Sr β 2.3 MeV

MACFLY 90Sr β, e-, e+,π, (CERN)

10,000 per spill

2.3 MeV

5-100 GeV

Coimbra 241Am (), 90Sr β 2.8 MeV

AIRFLY e-, e+ (DANE) 1-1010 25-800 MeV

FLASH e- (SLAC) 107-109 <1 MeV – 28.5 GeV

Madrid e- gun 1-1000 keV

TU Munich e- gun 12 keV

Brazil, Paris..

* : published paper(s)

Experimental approach:• Spectroscopy: ~ 1 nm• Narrow band filters: ~ 10 nm• Large band filters: ~ 100 nm


Published Nagano Results(reference)

15 wave bands measuredwith a 13% systematicuncertainty using narrow Band filter (Astropart. Phys. 22 (2004) 235)


Nagano(cont.)

FLY ~ 3.3 – 3.9 photons/m/e- @ 1atm

TiloTilo Waldenmaier International Workshop on Fluorescence Measurements Habère-Poche, 4th February 2005

The AirLight ExperimentThe AirLight ExperimentExperimental SetupExperimental Setup

• 9090Sr Electron Source:Sr Electron Source:– Endpoint Energy:Endpoint Energy: 2.3 MeV2.3 MeV– Activity:Activity: 37 MBq37 MBq– Rate @ Scintillator:Rate @ Scintillator: 10 – 20 kHz10 – 20 kHz

• 7 Photon Detectors:7 Photon Detectors:– Electrostatic + magnetic shieldingElectrostatic + magnetic shielding low dark rates, stable operationlow dark rates, stable operation– Dark rates: 400 – 500 Hz over thr.Dark rates: 400 – 500 Hz over thr.– 1 MUG-6 filter1 MUG-6 filter– 6 narrow band filters (FWHW: 10 nm)6 narrow band filters (FWHW: 10 nm) @ 317, 360, 380, 337, 391, 427 nm@ 317, 360, 380, 337, 391, 427 nm

• Gas:Gas:– NN22, Air, Air– Pressure range:Pressure range: 1 hPa – 1000 1 hPa – 1000

hPahPa– Temperature: Temperature: ~ 16 °C~ 16 °C

IWFM 05

MF1: Air pressure dependenceDL In Air for 50GeV e- at 28°C

Fluorescence : FLY = Edep . C/(1+P/P’)

Cerenkov : CDL = α P/Patm , α =0.6 mpe

Background : Cst = 1.6 mpe

Results:• C =0.76±0.1 photon/keV• P’ = 23.5 ±5 hpa

DL

(m

pe

) DL = FLY x εMF1 + CDL + Cst

Fit with 2 free parameters C and P’

measurement G4 simu Vacuum measurement

G4 simu+ calibration

G4 simuFly/Edep in photon/keV

FLYair (Patm) = 0.0172 ph/keV

Preliminary results

IWFM 05

MF1 vs other experiments

Kakimoto et al (96)

Bunner: (300 to 406)

Nagano et al (04)(300 to 406 nm)

Air Fly in photon/meter for 50GeV e- at 28°C

Macfly air FLY : 9% less than Nagano8% more than Kakimoto6% more than Bunner

Preliminary results

IWFM 05

Shower age dependence

Detected light in air for primary 50GeV e- at 25°C

Blue : 500 hpaRed : 100 hpa------ : GIL model (50 GeV e- in Cu)

IWFM 05

MF1: Energy DependenceEnergy air FLY at 950 hpa

≃ 1.5 MeV 3.2 ph/m

20 GeV 5.6 ph/m

50 GeV 5.7 ph/m

Air Fluorescence Light Yield

FL

Y (

ph

/m)

Kinetic Energy (MeV)

Macfly

Kakimoto

dE/dX curve

Preliminary results

Experimental set-up –July Experimental set-up –July 20042004

PM2 PM1

Interferencefilter

Fused silicawindows

Fused silicawindows

Freezer

PM1, PM2 - XP2020Q

PM3 – R1166

Cooling unit

Pressure sensor

to vacuum pump

PM3

scintillator

Temperaturesensor

gas input

Raw data (particle excitation)

-30 -20 -10 0 10 200,70

0,72

0,74

0,76

0,78

# C

oinc

/s

Temperature (ºC)

-20 -10 0 10 20

0,46

0,48

0,50

0,52

0,54-20 -10 0 10 20

0,30

0,32

0,34

0,36

0,38

-30 -20 -10 0 10 20 30

0,66

0,68

0,70

0,72

Temperature (ºC)

-20 -10 0 10 200,72

0,74

0,76

0,78

0,80

Temperature (ºC)

#Coi

nc/s

-20 -10 0 10 200,64

0,66

0,68

0,70

0,72

0,74

P0=818 hPa

= 0,80

P0=688 hPa

= 0,68

P0=434 hPa = 0,43

P0 = 520 hPa

= 0,51 o

P0 = 600 hPa

= 0,59 o


Outlook• Delicate measurements – Goal 10% syst.• All the projects are “Running Experiments”• Lines + Filters measurements performed

– Pressure dependence (all)– Temperature (Coimbra, AirFly)

• First Shower age FLY measurements– MacFly, FLASH

• Simulation G4– Needed, mature

• Absolute calibration– Cerenkov, Rayleigh,…– Difficult, needed

• Theory/Models– improving

Where the FLY story ends?

VHEPU-05 13-Mar-2005 P. N édélec - LAPP Air Fluorescence Light Yield Measurements Summary of the...

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