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RADIOACTIVE NUCLEI STOPPED IN NUCLEAR TRACK EMULSION
D.A. Artemenkov 1†
(1) V. I. Veksler and A. M. Baldin Laboratory of High Energy Physics
Joint Insitute for Nuclear Research, Dubna, Russia
† E-mail: artemenkov@lhe.jinr.ru
In the energy range of nuclei several MeV per nucleon, there is a possibility of implantation
of radioactive nuclei into detector material. Of course, in this approach daughter
nuclei are investigated rather than the nuclei themselves. In this respect it is worth mentioning
the known, although somewhat forgotten, possibilities of NTE for the detection
of slow radioactive nuclei. More than half a century ago, “hammer” tracks from the decay
of 8 Be nuclei through the first excited state 2 + of about 2.0 MeV were observed in
NTE. They occurred in the α decays of stopped 8 Li and 8 B fragments, which in turn
were produced by high-energy particles. Another example is the first observation of the
9 C nucleus from the decay 2α + p. When used with sufficiently pure secondary beams,
NTE appears to be an effective means for a systematic study of the decay of light nuclei
with an excess of both neutrons and protons. In NTE the directions and ranges of the
beam nuclei and slow products of their decay can be measured, which provides a basis for
α spectrometry. A question of major importance is to supplement the 3α spectroscopy of
12 N and 12 B decays with data on 3α angular correlations.
In March 2012 NTE was exposed at the Flerov Laboratory of Nuclear Reactions
(JINR) at the ACCULINNA spectrometer . The beam in use was enriched by 7 A MeV
8 He nuclei. A 107 µm thick NTE pellicle was oriented at a 10 ◦ angle during irradiation,
which provided approximately a five-fold effective thickness increase. For ten minutes
of irradiation, statistics of about two thousand of such decays was obtained. It is
pleasant to note that the used NTE have been recently reproduced by the enterprises
“Slavich” (Pereslavl-Zalessky, Russia).
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