Re: Radiochromic Dye Film Dosimetry

[DR MW CHARLES <charlemw@novell1.bham.ac.uk>]

Here at the University of Birmingham, England, we are interested in
the use of radiochromic dye film for hot particle dosimetry and would
be happy to share our experiences with the aimof improving dosimetry
and calculational methods .  

Just in case you are not aware - hot particles are high specific
activity but very small (<< 1mm dimensions) particles.  In the nuclear
industry hot particles arise from irradiated nuclear fuel or from
neutron activation of in-core microscopic 'debris'. 

We are mapping the doses around the particles with radiochromic dye
films , extrapolation chamber, and thermoluminescence dosimetry.  We
are also attempting to make calculations using Monte Carlo Codes and
VARSKIN.  We have produced a number of standard hot particles so that
we can validate measurements and calculations.  The main problems with
measurements are linked to the steep dose gradient.  There are
discrepancies between various measurement methods, particularly for
the dose averaged over very small areas immediately under the particle
- the peak dose.  This arises even for different methods of reading
out radiochromic dye film because of the different resolution of
different measuement systems.  Ideally we would like thinner
radiochromic films than those currently available and we would like
more sensitive materials with lower threshold doses - Do you have any
suggestions?  

The main problem on the calculational front is that the 
Monte Carlo codes seem to have problems transporting low energy 
electrons (< 30 keV) which are particularly important for low energy
beta sources such as Co-60 which is of particular importance in the
nuclear industry.  VARSKIN has a number of idiosyncracies when applied
to hot particles and does not adequately deal with the calculation of
dose from gamma radiation.  It needs more extensive validation. or
Auger electrons.


**********************************************************************


Date:          Tue, 26 Nov 96 13:57:51 -0600
Reply-to:      radsafe@romulus.ehs.uiuc.edu
From:          Bill Pitchford <Bill.Pitchford@asu.edu>
To:            Multiple recipients of list
<radsafe@romulus.ehs.uiuc.edu> Subject:       Radiochromic Dye Film
Dosimetry

Any RADSAFERs interested in conversing about high-dose high-rate
dosimetry?

1.	Applications

2.	Theoretical Considerations

3.	Practices

4.	Standards

5.	Potential markets

6.	Ongoing research


Bill Pitchford
Radiation Protection Facility
Arizona State University
Tempe, Arizona 85287-3501



Date:          Tue, 26 Nov 96 13:57:51 -0600
Reply-to:      radsafe@romulus.ehs.uiuc.edu
From:          Bill Pitchford <Bill.Pitchford@asu.edu>
To:            Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
Subject:       Radiochromic Dye Film Dosimetry

Any RADSAFERs interested in conversing about high-dose high-rate dosimetry?

1.	Applications

2.	Theoretical Considerations

3.	Practices

4.	Standards

5.	Potential markets

6.	Ongoing research


Bill Pitchford
Radiation Protection Facility
Arizona State University
Tempe, Arizona 85287-3501

Dr Monty Charles, Reader in Radiation Physics
School of Physics & Space Research
University of Birmingham
Edgbaston
Birmingham B15 2TT
England
TEL +44  0121 414 3483
FAX +44  0121 414 4725