Folie 1

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Forschungszentrum Karlsruhein der
Helmholtz-Gemeinschaft
Summary and Issues of
Workshop, Bad Liebenzell, Dec. 2003
Bianca Keilhauer
Tokyo, February 26th, 2004
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http//www.auger.de/events/air-light-03/

• 4 interesting days in December 2003
• 39 participants
• 25 presentations
• 10 projects
• ? improvements in understanding the aspects of
  molecular physics and in experimental
  measurements

3
Fluorescence Light - starting
theory -
A. N. Bunner Cosmic Ray Detection by Atmospheric
Fluorescence, PhD thesis 1967
Franck-Condon-Principle for absorption and
fluorescence
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Fluorescence from Nitrogen
N2
N2
1st Negative band
2nd Positive band
Data from Bunner (1964) weighted averages of
three experiments with an accuracy of not
better than 30. Kakimoto et al (1996)
1.4MeV-1000MeV are mainly used in UHECR
experiments.
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Energy Spectrum
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Discussion on Fluorescence Yield of an EAS
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Discussion on Fluorescence Yield of an EAS
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Ionization energy deposit problems

• Assumption
• No clear experimental evidence
• Precision of energy reconstruction will depend
  on fluorescence yield data
• Angular spread and definition of track length dX
• Track length along shower axis
• Actual track length of particles
• Energy loss in fluorescence yield experiments
• Low energy ( E Ec) ionization loss
• High energy ionization and radiative losses
  (small cascades)
• Detailed simulation of ionization energy deposit
  needed
• Calorimetric energy Ecal not equal to total
  shower energy

9
Dependencies
Excitation
Desexcitation
Measured dependencies today only E, P and
? Macfly project PO2,
PH2O, (T, nature)
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Excitation processes

• The C3Pu electronic state is a forbidden state
  it cannot be directly excited by fast charged
  particles.

H. Brunet, PhD thesis, UPS,Toulouse,1973
Elim (C3Pu) 11.03 eV P.I. 15.6 eV W 36 eV

Brunet PhD http//www.auger.de/events/air-light-0
3/phd_brunet
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Fluorescence Light

• EAS excites N2 molecules in air
• 18 transitions in 2P system between 300 and 400
  nm
• 1 transition in 1N system between 300 and 400 nm
• Calculation follows the principle way suggested
  by A. Bunner, 1967

? quantum efficiency of fluorescence
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Fluorescence Efficiency
with p/p? for air (79 N2 and 21 O2)
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Fluorescence Efficiency Profiles
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Electron impact cross sectionsfor N2 and O2
Qd
exc-S
el.
ion
ion
vib
vib
att
exc-T
rot
Dashed curves - excitations Magboltz -CERN
Pitchford and Phelps, MagBoltz
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Arqueros, Madrid, lt 30 keV
Nagano, Fukui Univ. Waldenmaier,
AirLight Gorodetzky, Paris Colin, MacFly 1.
phase Fraga, LIP-Lisboa Kemp, Campinas 1. phase
Privitera, AIRFLY, e-beam at BTF, 50-750 MeV
Colin, MacFly 2. ph., e/µ-beam at CERN
25-100 GeV Reil, Flash, e--beam at SLAC 28
GeV Kemp, 2. ph., e--beam at LNLS 1.37 GeV
Ulrich, Munich, 12 keV
2. phase medical acc. 5-12 MeV
16
Photon yields vs Bethe-Bloch

• FY seems to be proportional to dE/dx for E gt 0.8
  MeV.
• dE/dx grows fast at low energies. Does this
  relationship hold at very low energy?

17
Preliminary set-up the collision chamber
F. Blanco and M. Ortiz
HV (0 ? 30 kV )
NdYAG
vacuum pump
photodiode/trigger
collision chamber
gas inlet
PMT
Digital Scope
vacuum pump
UV filter
Faraday cup or scintillator

• Electron beam features
• Energy up to 30 KeV.
• Pulse Rate 1 20 Hz
• Time width 20 ns (limited by the laser /
  plasma).
• Intensity up to 200 mA peak.
• Beam diameter ? 2 mm.
• Some stability problems !!

• Differential pumping (up to 100 mtorr)
• 1 PMT ORIEL 77348 (single counting) UV
  filter
• Digital scope (1 ns)

18
High-precision Measurements of Experts
for Particle beam induced light emission
Energy deposition in the gas (1 bar Ar)
Parameters for low energy electron beam
excitation Particle energy typically 15 keV
Foil 300 nm silicon nitride
Gas typically 0.1 to 2 bar Beam current cw
typ. 10 µA av. (0.15 W) or pulsed
Modelled using the Casino Program P. Drouin,
A.R. Couture, R. Gauvin, P. Hovington, P. Horny,
H. Demers, Univ. de Sherbrooke, Quebec, Canada
(2002)
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Usage of the membranes (principle)
Diagnostics and gas system Time resolved optical
spectroscopy Grating monochromators (f30cm,
0.03 nm resolution
1.order) Wavelength range 30 nm to 700 nm
Time resolution 10ns beam pulses,
1ns electronic res.
Detectors VUV-PMT,VUV MCP and
diode array Sensitivity
measurements
two WI-17G Lamps (OSRAM) and
D2 arc-lamps (Cathodeon) Gas pressure
0 to 2 bar (foil 10 bar) Gas mixing
system with hot-metal gas
purifiers (rare gases) Capacitive
manometers (MKS Baratron)
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Assignment
III. Preliminary results from air Spectra
Overview, 1 bar, 12 keV electron beam excitation
High resolution spectrum
Preliminary result. Needs to checked!
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Arqueros, Madrid, lt 30 keV
Nagano, Fukui Univ. Waldenmaier,
AirLight Gorodetzky, Paris Colin, MacFly 1.
phase Fraga, LIP-Lisboa Kemp, Campinas 1. phase
Privitera, AIRFLY, e-beam at BTF, 50-750 MeV
Colin, MacFly 2. ph., e/µ-beam at CERN
25-100 GeV Reil, Flash, e--beam at SLAC 28
GeV Kemp, 2. ph., e--beam at LNLS 1.37 GeV
Ulrich, Munich, 12 keV
2. phase medical acc. 5-12 MeV
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Electron beam
average 0.85MeV
0.02
99.98
1.75MeV
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A and B of various bands
? For details N. Sakaki --- right after this
presentation
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AirLight Experiment

• Goals
• precise measurement of the ...
• pressure dependence
• temperature dependence
• effect of water vapor
• effect of oxygen and argon
• Filters nm 317, 340, 360, 380,
  394, 430, M-UG6

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Effective Transmission Curves ? Effective
Transmission Curve for every Filter can be
averaged.
Interference Filters Theory
Rel. Error using 0-Transmission gt 20 Rel.
Error using eff. Transmission lt 7
? CWL of filters should be 1-2 nm above the
observed wavelength.
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Bench Diagram
Source holder
Gaz injection
Source 90Sr
Fluorescence zone
Focusing lens
Spectrometer
integral PMT (PMT 2)
Spectrometer PMT (PMT 3)
Plastic scintillator

• PMT 1 below measures the 90Sr spectrum
  generates gates
• PMT 2 integral EUSO configuration 300-
  400 nm wavelength
• PMT 3 in spectrometer 1nm bandwidth

Probes (T, P)
Scintillator PMT (PMT 1)
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Macfly specificities
Event by event measurement Low electron density
like in air shower.

• Study of new dependencies
• Composition and contaminant (Macfly 1)
• Mainly O2 Percentage and Humidity
• Shower Age (Macfly 2)

Key point Real electromagnetic shower study
Shower S component electrons ??
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Results primary scintillation of N2
2nd pos. system
P 105 Pa T 296 K Dl 9 nm
H. Brunet, PhD thesis, UPS, Toulouse, 1973 a
(2.8 MeV)
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Quenching by water vapor
0-0 band intensity decreases with increasing
concentration of water vapor. Atmospheric
pressure was assumed.
Plans for the future

• Measurement of band intensities of the 2nd
  positive system as a function of pressure and
  temperature
• Study of the role of water vapor on the light
  yields and on the emission spectra.
• Participation in the tests at CERN in the SPS
  beam facility - proposal submitted by the Annecy
  group (RefMacFly-MEMO-01 of 11/24/2003)

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Chamber Configurations

• Particle Beam

e-

• Radioactive Source

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Relative EfficiencyGas Filling Dry Air ? N2

• Yi NE / NP
• NE coincidence excesses
• NP particle detector counting
• i gas type

YN2
YN2 / Yair 5.1 0.3 Kakimoto et al. , NIM 372A,
527 (1996) 5.6
Yair
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Arqueros, Madrid, lt 30 keV
Nagano, Fukui Univ. Waldenmaier,
AirLight Gorodetzky, Paris Colin, MacFly 1.
phase Fraga, LIP-Lisboa Kemp, Campinas 1. phase
Privitera, AIRFLY, e-beam at BTF, 50-750 MeV
Colin, MacFly 2. ph., e/µ-beam at CERN
25-100 GeV Reil, Flash, e--beam at SLAC 28
GeV Kemp, 2. ph., e--beam at LNLS 1.37 GeV
Ulrich, Munich, 12 keV
2. phase medical acc. 5-12 MeV
33
Beam monitoring with the calorimeter
The calorimeter is used for absolute and relative
beam intensity measurement (lt1000 e-/bunch)
Calorimeter counts single electrons
pedest.
1 e-
Time24 (s)
2 e-
3 e-
4 e-
ADC counts
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Energy dependence of fluorescence yield
UG6 filter
The scan was performed several times with
consistent results.
Preliminary
Np.e.(fluor.)
ADCcal x E/442
Limited by multiple scattering on 1.5 mm thick
exit Al window. The scan went down to 50 MeV.
Positrons (493 MeV) gave same yield within 3
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CERN Beam simulation
CERN-SPS-X5 50 GeV electron beam
Macfly2
Macfly1
Electrons Positrons
100 e- of 50 GeV
Only 1 e- of 50 GeV
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? For details J.N. Matthews --- right after the
coffee break
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• Exchange of already existing theoretical
  knowledge
• Exchange of practical solutions for experiment
  everyday life
• Fruitful discussion, even during night in the
  cellar
• Setup of an exchange platform on internet
  currently under construction

http//www.auger.de/events/air-light-03/