Joint Institute for Nuclear Research Relativistic ... - Index of - JINR

SUGGESTED INVESTIGATIONS CONCERNING UNRESOLVED EXPERIMENTAL
OBSERVATIONS
W. Westmeier 1 , R. Brandt 2 , S. Tyutyunnikov 3
1
Gesellschaft für Kernspektrometrie, D-35085 Ebsdorfergrund (Germany)
2
Philipps-Universität Marburg, D-35043 Marburg/Lahn (Germany)
3
Joint Institute for Nuclear Research, Dubna (Russia)
Evidence for unresolved experimental observations in nuclear interactions of high
energy ions in thick targets is published. These unexplained phenomena concern reactions
induced by secondary products originating from primary interactions with a hypothetical
centre-of-mass energy per nucleon E CM /u > 150 MeV. Below this centre-of-mass energy no
unresolved experimental evidences are observed.
Before considering possible reasons for this new effect, it is suggested to define the
experimental details and limitations for the unexplained observations more precisely. Several
experimental studies are proposed:
• Studies using a Cu target composed of 20 Cu disks of 1.0 cm thickness each and
irradiated with 12 C ions of several energies in the range from 0.6 GeV/u 12 C to 1.8
GeV/u 12 C
Yields of reaction products shall be measured in several 1.0 cm Cu disks together with the
neutron production rates in the complete target, using radiochemical, nuclear track and
counter techniques. This experiment shall give information about the onset of this
phenomenon.
• Re-measurement of unpublished preliminary results
One should re-measure in a quantitative manner a very large (but unpublished) neutron
fluence observed earlier in the irradiation of a 20 cm thick Cu target with 72 GeV 40 Ar. This
experiment is overdue for some 25 years.
• Studies on a 4 cm thick Cu target, composed of 20 Cu disks of 2 mm thickness each
and irradiated with 12 C ions at maximum energy, if possible with 44 GeV 12 C ions
[E CM /u = 488 MeV].
Yields of radioactive products shall be determined in all 0.2 cm Cu disks with radiochemical
methods. Of particular interest will be the comparison of the intensity variation in a sequence
of thin Cu disks for several key isotopes such as: 24 Na, 43 K, 52 Mn, and 59 Fe. Preliminary data
(not yet reproduced) exist only for the production of 24 Na in a target of 20 Cu disks (each 0.1
cm thin) irradiated with 44 GeV 12 C. One observed a rather “flat” distribution of 24 Na yields
within the first millimeters of Cu, followed by a strong yield increase further downstream.
This experiment should be reproduced and studied for various reaction products.
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