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Tagging Efficiency Measurements at High Intensities

Forsberg, Ulrika (2010) FYSK01 20102
Nuclear physics
Abstract (Swedish)
The Swedish National Laboratory MAX-lab contains a facility for production of bremsstrahlung
photons for photonuclear experiments. A so called "tagging technique" allows
for a determination of the energy of the individual photons via a spectrometric measurement
of the energy of the corresponding electron. Some of these photons are lost in a
collimation process. The fraction of photons in the collimated beam divided by the number
of particles that are detected in the spectrometer is called the tagging efficiency and
is used to determine the photon flux that impinges on the target, which is a parameter
that is needed in order to determine absolute cross sections.
The tagging efficiency depends on various factors, such as radiator... (More)
The Swedish National Laboratory MAX-lab contains a facility for production of bremsstrahlung
photons for photonuclear experiments. A so called "tagging technique" allows
for a determination of the energy of the individual photons via a spectrometric measurement
of the energy of the corresponding electron. Some of these photons are lost in a
collimation process. The fraction of photons in the collimated beam divided by the number
of particles that are detected in the spectrometer is called the tagging efficiency and
is used to determine the photon flux that impinges on the target, which is a parameter
that is needed in order to determine absolute cross sections.
The tagging efficiency depends on various factors, such as radiator thickness, steering
of the beam and collimator size, and is measured approximately once a day to make sure
that the experimental setup does not change in time. The measurements are usually
made at an intensity that is several orders of magnitude lower than during production
runs, due to the fact that a detector has to be placed directly in the photon beam. It
is assumed that the measured tagging efficiency is the same as the tagging efficiency at
high intensities, but this has not been verified before for the upgraded facility that was
built in 2005.
This thesis presents measurements of the tagging efficiency at various intensities at
the new facility, showing that the tagging efficiency is independent of intensity and that
there is no systematic error in measuring it at much lower intensities than under normal
experimental conditions. The measurements at high intensities were done using lead
absorbers that attenuated the photon beam. The experimental setup and the analysis
of the data is presented. The tagging efficiency was found to be, within error bars,
independent of the intensity over three orders of magnitude, ranging up to approximately
4% of full intensity. (Less)
Please use this url to cite or link to this publication:
author
Forsberg, Ulrika
supervisor
organization
course
FYSK01 20102
year
type
M2 - Bachelor Degree
subject
language
English
id
1664740
date added to LUP
2010-09-01 11:52:19
date last changed
2010-09-01 17:01:42
@misc{1664740,
  abstract     = {The Swedish National Laboratory MAX-lab contains a facility for production of bremsstrahlung
photons for photonuclear experiments. A so called "tagging technique" allows
for a determination of the energy of the individual photons via a spectrometric measurement
of the energy of the corresponding electron. Some of these photons are lost in a
collimation process. The fraction of photons in the collimated beam divided by the number
of particles that are detected in the spectrometer is called the tagging efficiency and
is used to determine the photon flux that impinges on the target, which is a parameter
that is needed in order to determine absolute cross sections.
The tagging efficiency depends on various factors, such as radiator thickness, steering
of the beam and collimator size, and is measured approximately once a day to make sure
that the experimental setup does not change in time. The measurements are usually
made at an intensity that is several orders of magnitude lower than during production
runs, due to the fact that a detector has to be placed directly in the photon beam. It
is assumed that the measured tagging efficiency is the same as the tagging efficiency at
high intensities, but this has not been verified before for the upgraded facility that was
built in 2005.
This thesis presents measurements of the tagging efficiency at various intensities at
the new facility, showing that the tagging efficiency is independent of intensity and that
there is no systematic error in measuring it at much lower intensities than under normal
experimental conditions. The measurements at high intensities were done using lead
absorbers that attenuated the photon beam. The experimental setup and the analysis
of the data is presented. The tagging efficiency was found to be, within error bars,
independent of the intensity over three orders of magnitude, ranging up to approximately
4% of full intensity.},
  author       = {Forsberg, Ulrika},
  language     = {eng},
  note         = {Student Paper},
  title        = {Tagging Efficiency Measurements at High Intensities},
  year         = {2010},
}