Optimisation of Scintillation Counters.
1. Project goals.
Your team has been commissioned to optimise systems for getting light
out of plastic scintillators for a number of different projects which
involve efficient detection of particles. Two projects which are
immediately interested in buying your system, when developed, are:
* the MINOS neutrino detector which is being designed now;
* a muon lifetime measurement project in the M.Sci. 4th year.
The final output of your design study will be a fully operational test
setup and accompanying software simulation, documented and flexible
enough for future general use, as well as initial test results and
recommendations on choice of scintillator geometry.
2. Information collection.
In order to successfully complete the design, it is likely that your
team will need to undertake a certain amount of background work. This
will probably include the following.
(a). Understanding the basic physics of scintillators and optical
fibres.
(b). Performance of available scintillator, and optical fibres,
including light yield, attenuation length and reflection angles.
(c). Performance of available photodetectors,
including their sensitivity, area, speed of response and angular
resolution.
You will probably find the more general initial project commissioned
last year on scintillator design a useful source.
3. Simulation and optimisation of scintillator shape and fibre position.
A software package should be written to simulate light production in a
scintillator as a particle passes through it, and collection of the
light by optical fibre attached to the scintillator. The package
should allow you and the subsequent users to adjust:
(a) Internal reflection angles, light yield and
attenuation in the scintillator.
(b) Shape of scintillator.
(c) Position of fibres on scintillator.
The package should output light collection efficiency as well as the
intensity, position and angle of light rays collected in the fibre.
4. Simulation and optimisation of fibre length.
Produce a software package to simulate propagation of light along an
optical fibre. The package should be able to read the output of the
scintillator simulation (above) and output the overall attenuation,
time dispersion and angular dispersion of light emerging from the end
of the fibre. This should be possible for a range of fibre lengths and
properties.
5. LED Test setup.
A test setup which allows light from an LED to be fired into a
scintillator, collected by a fibre and measured in a photomultiplier
must be constructed. This should be used to validate the simulation
results for a limited number of geometries and to test the final
recommendation.
6. Resources available.
You have available 2 hours of consultation time on the engineering
aspects, and another 2 hours for consulting experts in scintillator
physics and/or software design. Your consultants are Mr B.E. Anderson
for the former, and Prof. D.J. Miller, Dr. J.M Butterworth and Dr
J. Thomas for the latter.
Your Board Member is Dr J.M. Butterworth, phone 7318, email
jmb@hep.ucl.ac.uk.