Table 3
Modification of the Procedure used for Fission Track Autoradiography of
Marchaii’ latands Teeth Samples
Step
Modification
Dehydcation
none
Infiltration
none
Embedding and Curing
instead of Solution B from Polysciunce Inc. as
accelerator, use 2,2' Azobisiso butyrontrile
ALBN (0.5% by weight).
The methyl methacrylate plus ALBN will be exposed
to uv light,overnight-1 day.
The new procedure should result in a harder polymer.
To provide easy release of the specimen from the
mold, a release agent such as silicon grease (20%
py wt.) dissolved in methyl methacrylate can be
used Co coat the inside of the glass mold.
Sectioning
Sections as
Preparation for
a)
If Al
thin as
250 om will]
be attempted.
foil were
to be used,
several pieces
of
lexan or polyethylene ¢ises snould be placed
between the foil and the "teeth sandwich"
Irradiation
b)
A new set-up without the use of Al foil is
being planned
Instead of the "rabbit" pneumatic tube irradiation
Ivrvadiation
facility, the “aluminum can' radial set-up will
be used;
the former has an hf ease ratio of 33
and temperature is greater than or equal to 50°C
whereas the latter has a ratio _of 300 and temp.
is greater than or equal to 30°C.
Irradiation
time has to be increased considgrably
ince the
Former has a neutron flux os 10
“ng/em' sec
whereas the latter of 3xlL0
nt/em sec, smaller
by a factor of 3.
The irradiation time used
previously is too short, as observed from the Pu
tracks, and may have to be increased 2 &.
Thus
the new irradiation time may be 8-10 hrs.
Etching
for long irradiation i dine , grgater than or equal
to JO hers at the 3x10
nt/eom sec flux, Billie
Oltman of SNL aiyeests Lower temperalure and lon-
ger etching time, 44°C,
90 minutes.
If 60°C is to
be retained, 35 minutes etching time was recommended.
He also recommends partial immersion instead of
total immersion- etch the side against the teeth
specimen only.
The set-up used at ANL is 6.25M
KOH in a 1500 mL pyrex tray on top of a hot plate
with temperature measured by a thermometer.
This
should improve signal
—<
an
=
=
2
\
make
to noise ratio and also
track counting Jess
confusing.