Čerenkov photon density fluctuations in extensive air showers

Chitnis, V. R.; Bhat, P. N.

doi:10.1016/s0927-6505(98)00007-3

Cited by 18 publications

(31 citation statements)

References 11 publications

(17 reference statements)

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“…As an example, a primary energy of 100 GeV (MC set I) has been chosen. Similar correlations between the shower size and the height of the first interaction were presented in [9].…”

Section: Monte Carlo Simulationssupporting

confidence: 76%

“…The effect of the Cherenkov photon absorption in the atmosphere enlarges the relative fluctuations of the shower Limits to the energy resolution of a single Air Cherenkov Telescope at low energies 8 The same quantity is shown in figure 4d for the proton primaries. The relative fluctuations of the shower size decrease from 40% at 50 GeV to 29% at 1 TeV in the case of MC set I and this result is also a little higher than that presented in [9]. The influences of the limited detector FOV and the atmospheric absorption are also presented in this figure.…”

Section: Shower Size Fluctuationsmentioning

confidence: 49%

“…This ratio calculated from MC set I decreases from 6% to 5%, while the energy increases from 100 GeV to 500 GeV. Slightly lower results (from 5% at 100 GeV to 3% at 1 TeV) were published in [9], but they were obtained from lower statistics and for different wavelengths, so the results are consistent. The limited FOV has significantly influenced the calculated ratio only for primary energies below 100 GeV (dashed line on the plot).…”

Section: Shower Size Fluctuationsmentioning

confidence: 74%

“…This results in a larger shower size. In the case of primary protons the correlations between the shower size and the first interaction height are not observed [9].…”

Section: Introductionmentioning

confidence: 99%

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Limits to the energy resolution of a single air Cherenkov telescope at low energies

Sobczyńska¹

2009

J. Phys. G: Nucl. Part. Phys.

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Abstract. The photon density on the ground is a fundamental quantity in all experiments based on Cherenkov light measurements, e.g. in the Imaging Air Cherenkov Telescopes (IACT). IACT's are commonly and successfully used in order to search and study Very High Energy (VHE) γ-ray sources. Difficulties with separating primary photons from primary hadrons (mostly protons) in Cherenkov experiments become larger at lower energies. I have calculated longitudinal and lateral density distributions and their fluctuations at low energies basing on Monte Carlo simulations (for vertical γ cascades and protonic showers) to check the influence of the detector parameters on the possible measurement. Relative density fluctuations are significantly higher in proton than in photon induced showers. Taking into account the limited detector field of view (FOV) implies the changes of these calculated distributions for both types of primary particles and causes an enlargement in relative fluctuations. Absorption due to Rayleigh and Mie scattering has an impact on mean values but does not change relative fluctuations. The total number of Cherenkov photons is more sensitive to the observation height in γ cascades than in proton showers at low primary energies. The relative fluctuations of the density do not depend on the reflector size in the investigated size range (from 240 m 2 up to 960 m 2 ). This implies that a single telescope with a mirror area larger than that of the MAGIC telescope cannot achieve better energy resolution than estimated and presented in this paper. The correlations between longitudinal and lateral distributions are much more pronounced for primary γ-ray than for primary proton showers.PACS numbers: 95.55. Ka;95.55.Vj;95.85.Pw;95.85.Ry

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“…As an example, a primary energy of 100 GeV (MC set I) has been chosen. Similar correlations between the shower size and the height of the first interaction were presented in [9].…”

Section: Monte Carlo Simulationssupporting

confidence: 76%

Section: Shower Size Fluctuationsmentioning

confidence: 49%

Section: Shower Size Fluctuationsmentioning

confidence: 74%

“…This results in a larger shower size. In the case of primary protons the correlations between the shower size and the first interaction height are not observed [9].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Limits to the energy resolution of a single air Cherenkov telescope at low energies

Sobczyńska¹

2009

J. Phys. G: Nucl. Part. Phys.

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“…Unfortunately these kind of telescopes, in spite of the Cotton-Devis design [7], have non-negligible aberrations-one of the sources of worsening the γ selection. The γ /hadron separation becomes more difficult in the low energy region because of higher relative fluctuations in the shower development, causing larger fluctuations of the Cherenkov light density [8] and image parameters.…”

Section: Introductionmentioning

confidence: 99%

A Structural Study of Ag-Rich Ag–As–S Glasses

Kawaguchi

1998

Jpn. J. Appl. Phys.

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The γ /hadron separation in the imaging air Cherenkov telescope technique is based on differences between images of a hadronic shower and a γ induced electromagnetic cascade. One may expect for a large telescope that a detection of hadronic events containing Cherenkov light from one γ subcascade only is possible. In fact, simulations show that for the MAGIC telescope their fraction in the total protonic background is about 1.5% to 5.2% depending on the trigger threshold. It has been found that such images have small sizes (mainly below 400 photoelectrons) which correspond to the low energy primary γ 's (below 100 GeV). It is shown that parameters describing shapes of images from one subcascade have similar distributions to primary γ events, so those parameters are not efficient in all methods of γ selection. Similar studies based on MC simulations are presented also for the images from 2γ subcascades which are products of the same π 0 decay. The ratio of the number of the expected background from false γ and one π 0 to the number of the triggered high energy photons from the Crab direction has been estimated for images with a small alpha parameter to show that the occurrence of this type of protonic shower is the reason for the difficulties with true γ selection at low energies. Communicated by Professor M Giller

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Very high energy γ-rays from galactic sources

Vishwanath

2002

J Astrophys Astron

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Čerenkov photon density fluctuations in extensive air showers

Cited by 18 publications

References 11 publications

Limits to the energy resolution of a single air Cherenkov telescope at low energies

Limits to the energy resolution of a single air Cherenkov telescope at low energies

A Structural Study of Ag-Rich Ag–As–S Glasses

Very high energy γ-rays from galactic sources

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