K5 emulsions 10 mum thick were exposed at various depths in a perspex phantom to a 70 MeV pi- meson beam and counts taken of the tracks in emulsion volumes 7x7x10 mum3. Data are presented on the number of track events and also the total number of grains associated with each event in each of four categories spanning the LET range of the secondary particles. The number of heavy tracks (category 4) shows an increased incidence in the region of the stopping pi- mesons (14-5 cm in perspex) while the number of single grains (category 1) decreases with depth. Categories 2 and 3 (grain clusters and light tracks) are approximately constant with depth. An estimate of the grain sensitivity is obtained by taking the proton as representative of the whole range of secondary particles. This procedure gives a value of 5 keV per grain in the pi- peak. The LET of light tracks was therefore in the range 1-10 keV mum-1 in emulsion, scaling to 0-4-4 keV mum-1 in water. Heavy tracks have LET values in excess of 4 keV mum-1 in water.
[1]
D. R. Perry,et al.
Determination of RBE values for fast neutrons and negative phi-mesons using frozen HeLa cells.
,
1974,
The British journal of radiology.
[2]
K. C. Chandler,et al.
Calculations related to the application of negatively charged pions in radiotherapy: absorbed dose, LET spectra, and cell survival.
,
1974,
Radiation research.
[3]
M. R. Raju.
Negative pions in radiotherapy: a brief review.
,
1974,
European journal of cancer.
[4]
C. Parnell.
A fast neutron spectrometer and its use in determining the energy spectra of some cyclotron-produced fast neutron beams.
,
1972,
The British journal of radiology.
[5]
L. Caro,et al.
HIGH-RESOLUTION AUTORADIOGRAPHY : I. Methods
,
1962
.
[6]
A. James,et al.
Alpha-particle incidence in small targets.
,
1970,
Physics in medicine and biology.