NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Collections About News Help Login
Back to Results
In-Flight Measurement of the Absolute Energy Scale of the Fermi Large Area TelescopeThe Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope is a pair-conversion telescope designed to survey the gamma-ray sky from 20 MeV to several hundreds of GeV. In this energy band there are no astronomical sources with sufficiently well known and sharp spectral features to allow an absolute calibration of the LAT energy scale. However, the geomagnetic cutoff in the cosmic ray electron- plus-positron (CRE) spectrum in low Earth orbit does provide such a spectral feature. The energy and spectral shape of this cutoff can be calculated with the aid of a numerical code tracing charged particles in the Earth's magnetic field. By comparing the cutoff value with that measured by the LAT in different geomagnetic positions, we have obtained several calibration points between approx. 6 and approx. 13 GeV with an estimated uncertainty of approx. 2%. An energy calibration with such high accuracy reduces the systematic uncertainty in LAT measurements of, for example, the spectral cutoff in the emission from gamma ray pulsars.
Document ID
20140010258
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
doi:10.1016/j.astropartphys.2011.10.007
Authors
Ackermann, M. (Stanford Univ. Stanford, CA, United States)
Ajello, M. (Stanford Univ. Stanford, CA, United States)
Allafort, A. (Stanford Univ. Stanford, CA, United States)
Atwood, W. B. (California Univ. Santa Cruz, CA, United States)
Axelsson, M. (Stockholm Univ. Sweden)
Baldini, L. (Istituto Nazionale di Fisica Nucleare Pisa, Italy)
Barbielini, G (Istituto Nazionale di Fisica Nucleare Trieste, Italy)
Bastieri, D. (Istituto Nazionale di Fisica Nucleare Padova, Italy)
Bechtol, K. (Stanford Univ. Stanford, CA, United States)
Bellazzini, R. (Istituto Nazionale di Fisica Nucleare Pisa, Italy)
Berenji, B, (Stanford Univ. Stanford, CA, United States)
Bloom, E. D. (Stanford Univ. Stanford, CA, United States)
Bonamente, E. (Istituto Nazionale di Fisica Nucleare Perugia, Italy)
Borgland, A. W. (Stanford Univ. Stanford, CA, United States)
Bouvier, A. (California Univ. Santa Cruz, CA, United States)
Bregeon, J. (Istituto Nazionale di Fisica Nucleare Pisa, Italy)
Brez, A. (Istituto Nazionale di Fisica Nucleare Pisa, Italy)
Brigida, M. (Bari Univ. Italy)
Bruel, P. (Ecole Polytechnique Palaiseau, France)
Buehler, R. (Stanford Univ. Stanford, CA, United States)
Gehrels, N. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Hays, E. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
McEnery, J. E. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Thompson, D. J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Troja, E. J. (Maryland Univ. College Park, MD, United States)
Date Acquired
July 29, 2014
Publication Date
January 1, 2012
Publication Information
Publication: Astroparticle Physics
Publisher: ELSEVIER
Volume: 35
Issue: 6
Subject Category
Astronomy
Report/Patent Number
GSFC-E-DAA-TN9662
Funding Number(s)
CONTRACT_GRANT: NNG06EO90A
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
Cosmic-rays
In-flight measurement
absolute energy

Related Records

There are no records associated with this record.
No Preview Available