nitrogen fluorescence in air for observing extensive air showers
DESCRIPTION
Nitrogen fluorescence in air for observing extensive air showers. B . Keilhauer. 8th Air Fluorescence Workshop Karlsruhe, 12 – 14 September 2011. Delegation of the workshop: M. Bohacova M. Fraga B. Keilhauer J. Matthews N. Sakaki Y. Tameda Y. Tsunesada A. Ulrich. - PowerPoint PPT PresentationTRANSCRIPT
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KIT – Universität des Landes Baden-Württemberg undnationales Großforschungszentrum in der Helmholtz-Gemeinschaft
AtmoHEAD: Atmospheric Monitoring for High-Energy Astroparticle Detectors, Saclay, 10 – 12 June 2013
www.kit.edu
Nitrogen fluorescence in air for observing extensive air showers
B. Keilhauer
8th Air Fluorescence WorkshopKarlsruhe, 12 – 14 September 2011
http://www.kceta.kit.edu/8afw2011/
Delegation of the workshop:
M. BohacovaM. FragaB. KeilhauerJ. MatthewsN. SakakiY. TamedaY. TsunesadaA. Ulrich
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2 10. June 2013B. Keilhauer AtmoHEAD 2013
Eur. Phys. J. Plus (2012) 127: 87
V. Berezinsky, UHECR2012
Interpretation of Cosmic Rays
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3 10. June 2013B. Keilhauer AtmoHEAD 2013
Interpretation of Cosmic Rays- scaling of the absolute energy -
direct data of the experiments re-scaled data
Prog. Part. Nucl. Phys. 63 (2009) 293
J(E
)E3
, eV
2 m
-2 s
-1 s
r-1
E , eV E , eV
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4 10. June 2013B. Keilhauer AtmoHEAD 2013
Interpretation of Cosmic Rays- determination of the composition -
M. Unger, UHECR2012
Astroparticle Physics 39–40 (2012) 33–43
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5 10. June 2013B. Keilhauer AtmoHEAD 2013
Air shower
Emission of isotropic Fluorescence-
and forward-beamed Cherenkov-light
Transmission
Shower axis
Detection Principles
Transmission
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6 10. June 2013B. Keilhauer AtmoHEAD 2013
Fluorescence Light Production excitation of nitrogen in air because
of energy deposit from EAS direct excitation of 1N via ionization
collisions with low energy electrons with spin change for 2P
down cascading from higher level of 2P
spontaneous de-excitation → fluorescence light
A.N. Bunner, PhD thesis, Cornell, 1967
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7 10. June 2013B. Keilhauer AtmoHEAD 2013
Fluorescence Light Production
excitation of nitrogen in air because of energy deposit from EAS spontaneous de-excitation → fluorescence light atmosphere dependence because of quenching
NIM A597(2008)41
800 hPa, 293 K
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8 10. June 2013B. Keilhauer AtmoHEAD 2013
Formulas for a Fluorescence Description
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9 10. June 2013B. Keilhauer AtmoHEAD 2013
Formulas for a Fluorescence Description
a) absolute yield value of a reference transmission: fluorescence yield in photons emitted per MeV of energy deposited at given experimental conditions p0 and T0
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10 10. June 2013B. Keilhauer AtmoHEAD 2013
Formulas for a Fluorescence Description
a) absolute yield value of a reference transmission
b) wavelengths-dependent spectrum:
ratio of individual transitions of the spectrum between about 280 and 430 nm to the strength of the transitions at 337.1 nm
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11 10. June 2013B. Keilhauer AtmoHEAD 2013
Formulas for a Fluorescence Description
a) absolute yield value of a reference transmission
b) wavelengths-dependent spectrum
c) pressure dependence in dry air:
characteristic pressure of dry air at experimental conditions T0
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12 10. June 2013B. Keilhauer AtmoHEAD 2013
Formulas for a Fluorescence Description
a) absolute yield value of a reference transmission
b) wavelengths-dependent spectrum
c) pressure dependence in dry air
d) humidity quenching:
p′H2O(λ, T0) - characteristic pressure of water vapor at experimental conditions T0
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13 10. June 2013B. Keilhauer AtmoHEAD 2013
Formulas for a Fluorescence Description
a) absolute yield value of a reference transmission
b) wavelengths-dependent spectrum
c) pressure dependence in dry air
d) humidity quenching
e) temperature-dependent collisional cross sections:
αλ- exponent of the power law describing the T-dependent collisional cross sections for each λ
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14 10. June 2013B. Keilhauer AtmoHEAD 2013
Formulas for a Fluorescence Description
Non-radiative de-excitation of excited nitrogen moleculesÞ only 1 value for
each band system
a) absolute yield value of a reference transmission
b) wavelengths-dependent spectrum
c) pressure dependence in dry air
d) humidity quenching
e) temperature-dependent collisional cross sections
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15 10. June 2013B. Keilhauer AtmoHEAD 2013
Strategy
1. Describing the spectrum and the dependences on atmospheric conditions:
Þ common altitude-dependent shapeÞ requires adequate knowledge of atmospheric profiles
2. Finding the absolute scaling:
Þ direct shift of reconstructed primary E of air showers
b) wavelengths-dependent spectrum
c) pressure dependence in dry air
d) humidity quenching
e) temperature-dependent collisional cross sections
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16 10. June 2013B. Keilhauer AtmoHEAD 2013
Suggested Reference Fluorescence Description- spectral intensities -
spectral intensities Iλ as measured by AIRFLY; 34 transitions between 296 and 428 nm
The sum of the yield differs by -1.66% (Ulrich et al.),+2.08% (Nagano et al.),-1.70% (FLASH).
B. Keilhauer et al. , proc. UHECR 2012
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17 10. June 2013B. Keilhauer AtmoHEAD 2013
Suggested Reference Fluorescence Description- pressure dependence-
p‘air : - one value for each band system;
- weighted averages for 2P(0,x), (1,x), (2,x), (3,x), 1N (0,x), (1,x), GH (0,x) derived from AIRFLY measurements;
- for weak transitions, as 2P(4,x), further GH, estimates from their publicatation
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18 10. June 2013B. Keilhauer AtmoHEAD 2013
Suggested Reference Fluorescence Description- humidity dependence-
p‘H2O : - one value for each band system;
- weighted averages for 2P (0,x), (1,x), (2,x), 1N (0,x) derived from Sakaki et al. measurements using the photon yield and the lifetime technique
- for weak transitions of 2P(3,x) and 2P(4,x) use weighted average of p‘H2O of 2P (1,x) and (2,x) bands (4.8% of the total emission at p0, T0)
- for all others set to Zero (2.1% of the total emission at p0, T0)
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19 10. June 2013B. Keilhauer AtmoHEAD 2013
N. Sakaki, 8AFW 2011
Systematic study from Sakaki et al.- humidity dependence-
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20 10. June 2013B. Keilhauer AtmoHEAD 2013
Suggested Reference Fluorescence Description- temp.-dep. collisional cross sections -
α-coefficient : - one value for each band system;
- weighted average for 2P(0,x) and 1N(0,x) derived from AIRFLY measurements
- for weak transitions of 2P(3,x) and 2P(4,x) use weighted average of p‘H2O of 2P (1,x) and (2,x) bands (4.8% of the total emission at p0, T0)
- for all others set to Zero (2.1% of the total emission at p0, T0)
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21 10. June 2013B. Keilhauer AtmoHEAD 2013
Parameter Set for the Reference
Fluorescence Description
B. Keilhauer et al. , proc. UHECR 2012
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22 10. June 2013
„academic“ fluorescence yield- scaling according Nagano et al. (2004) -
Y. Tsunesada et al. , proc. ICRC 2013
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23 10. June 2013
„academic“ fluorescence yield- variations of p‘H2O -
B. Keilhauer et al. , proc. UHECR 2012B. Keilhauer AtmoHEAD 2013
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24 10. June 2013
„academic“ fluorescence yield- variations of -
B. Keilhauer et al. , proc. UHECR 2012B. Keilhauer AtmoHEAD 2013
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25 10. June 2013
Application to air shower reconstruction- same absolute scaling, Auger reconstruction framework -
Mean: -9.98 % 0.34 % Mean: 0.71 g cm-2 1.63 g cm-2
RMS: 1.76 % 1.22 % RMS: 1.25 g cm-2 3.56 g cm-2
B. Keilhauer et al. , proc. UHECR 2012B. Keilhauer AtmoHEAD 2013
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26 10. June 2013
Systematics in air shower reconstruction- same absolute scaling, Auger reconstruction framework -
B. Keilhauer et al. , proc. UHECR 2012B. Keilhauer AtmoHEAD 2013
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27 10. June 2013
Systematics in air shower reconstruction- same absolute scaling, Auger reconstruction framework -
B. Keilhauer et al. , proc. UHECR 2012B. Keilhauer AtmoHEAD 2013
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28 10. June 2013
Systematics in air shower reconstruction- same absolute scaling, Auger reconstruction framework -
B. Keilhauer et al. , proc. UHECR 2012B. Keilhauer AtmoHEAD 2013
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29 10. June 2013
Application to air shower reconstruction- different absolute scaling -
Mean: 0.3 %
Mean: 8.6 %
Mean: 0.7 g cm-2
Mean: -6.6 g cm-2
both „Nagano“-scaling
TA „Kakimoto“-scaling
B. Keilhauer AtmoHEAD 2013
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30 10. June 2013
Influence of atmospheric profiles
B. Keilhauer AtmoHEAD 2013
monthly models
GDAS
Astropart. Phys. 35 (2012) 591
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31 10. June 2013
Conclusion
• a reference fluorescence description has been developed
• all known atmospheric effects are implemented
• application to air shower reconstructions are done for Auger and TA, but not used in the official experiments‘ reconstructions yet
first details are published in the proc. of UHECR2012
more in the proc. of ICRC 2013