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"The results of this study are of characteristically high quality but there is insufficient internal redundancy to warrant conviction at this stage. Confirmation by further results is needed to assign priority of discovery to this collaboration." S. Hofmann, V. Ninov, F. P. Hessberger, P. Armbruster, H. Folger, G. Munzenberg, H. J. Schott, A. G. Popeko, A. V. Yeremin, S. Saro, R. Janik, M. Leino. "The new element 112", Z. Phys. A 354, 229230 (1996).
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Using
the
electromagnetic
velocity
filter SHIP,
fusion-like
residues
of
the
reaction
of
70Zn
with
enriched
208Pb
targets
were measured.
Two
chains
of
localized
alpha-emitters
were
identified
as
originating
with
277112.
The
quality
of
the
data
is
very
high. However,
regarding
the
complete criteria,
there
is
only
one
incidence
of redundancy,
that
assigned
to
the
previously
uncharacterized
isotope
269Hs
that
appears
in
both events;
there
is
no
redundancy
involving
known daughters.
The
observed
alpha
leads
to
the
known
isotope
265Sg,
but
then
reports
a
261Rf
alpha
energy
that
is
in
significant
disagreement
with
known energies,
posing
uncertainty
with
the assignment.
The
last
alpha
in
the
chain
agrees
extremely
well
with
that
of
descendant
257No,
but
is
the
only
concordant
daughter
comparison
event
of
the
entire
112 set.
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Reference reports its 273Ds alpha particle with energy 11.35 MeV in agreement with this Hofmann et al. groups 11.45 MeV when resolution is taken into account. There are other chains in this reference noted with less confidence, but that nevertheless do not provide further redundancy to these results by Hofmann et al. |
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The
Hofmann
et
al.
collaboration
reports
on
one
new
chain
originating
from
278112
in
the
70Zn
+
208Pb reaction. However,
re-analysis
of
the
previous
report
two
chains
was
unable
to
confirm
the
original
results
for
the
first
chain
as
noted above.
Hofmann
et
al.
thus
have
a
total
of
two
alpha
and
lifetime
chains
of
events
originating
with
the
new
isotope
277112
leading
to
two
alpha
and
lifetime
events
of
273Ds,
in
good
agreement
with
a
single
observation
assigned
to
273Ds
by
Lazarev
et
al.
in
their
tenuous chain.
The
chains
continue
to
the
previously
unknown
269Hs
for
which
alpha
energies
and
lifetimes
are
similar
in
both events.
The
Hofmann
et
al.
chains
continue
through
265Sg,
but
with
no
alpha energies.
The
lifetimes
seen
are
consistent
with
8
s
from
a
previous
study
of
265Sg
but
not
with
158
s found.
Only
the
first
chain
of
Hofmann
et
al. resumes,
producing
261Rf
with
an
8.52
MeV
alpha
and
4.7
s lifetime.
The
alpha
energy
is
in
agreement
with
the
literature value,
but
the
lifetime
is
not.
This
situation
is
also
somewhat
confounded
by
the
study
of
261Rf. Here,
8.30
MeV (but
no
8.52
MeV)
alpha
particles
are
observed
for
which
the
lifetime
is
acknowledged
to
be
78
s.
As
mentioned previously,
the
first
277112
chain
ultimately
decays
through
an
alpha
and
lifetime
in
very
good
agreement
with
that
for
the
known
isotope
257No.
In summary, though,
there
are
only
two chains,
and
neither
is
completely
characterized
on
its
own merit. Supportive,
independent
results
on
intermediates
remain
less
than
completely
compelling
at
this stage.
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The
collaborations
of
Oganessian
et
al.
used
the
reactions
48Ca
+
242Pu
and
48Ca
+
244Pu,
respectively,
each
to
make
one
observed
chain
originating
with
287114
and
289114,
respectively,
which
pass
through
unknown
intermediates
terminating
in
spontaneous
fission.
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The Dubna collaboration of Oganessian et al. used the reaction 48Ca + 238U to make 283112 in which the two events decay by spontaneous fission with a lifetime of ~2 min. An independent repeat of the © 2003 IUPAC, Pure and Applied Chemistry 75, 16011611 On the claims for discovery of elements 110, 111, 112, 114, 116, and 118 1605 same experiment, however, did not lead to any events nor did another independent attempt to follow the eka-Hg chemistry of element 112 produced by the same path lead to any events. W. Loveland, K. E. Gregorich, J. B. Patin, D. Peterson, C. Rouki, P. M. Zielinski, K. Aleklett. Search for the production of element 112 in the 48 Ca + 238 U reaction, Phys. Rev. C 66, 044617-1-5 (2002). A. B. Yakushev, G. V. Bulkanov, M. L. Chelnokov, V. I. Chepigin, S. N. Dmitriev, V. A. Gorshkov, S. Hübener, V. Ya. Lebedev, O. N. Malyshev, Yu. Ts. Oganessian. First attempt to chemically identify element 112, Radiochim. Acta 89, 743 (2001).
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The Oganessian et al. collaborations, in which 244Pu + 48Ca in the first and 248Cm + 48Ca in the second case are used to produce decay chains commencing with 288114 or 292116, respectively, followed by a pair of well-reproduced ±-decays assigned to the otherwise unknown 284112 and terminating in spontaneous fission of previously unknown 280Ds. The decay energies and lifetimes of three events for 284112 are internally redundant, but no link to recognized nuclei occurs. In the 244Pu + 48Ca study, another event originating with 289114 followed by a chain observed through 285112 and 281Ds terminates with spontaneous fission at 277108, all previously unknown. The Dubna collaborations have performed careful, high-quality studies whose acknowledgement as discoveries is unfortunately not yet warranted because of unsecured connection to known descendents and unobserved elemental signatures (such as well-resolved X-ray energies). Yu. Ts. Oganessian, V. K. Utyonkov, K. J. Moody. "Synthesis of 292116 in the 248Cm + 48Ca reaction¡", Phys. Atom. Nucl. 64, 1349¨C1355 (2001).
Yu.
Ts.
Oganessian,
V.
K.
Utyonkov,
Yu.
V.
Lobanov,
F.
Sh.
Abdullin,
A.
N.
Polyakov,
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This collaboration continues to press arguments favoring their discovery of element 112 through the existence of very long-lived isomeric states of actinides and transactinides, of very high fusion cross-sections for their formation, each several orders of magnitude beyond traditional understanding. As indirect evidence, their discovery of long-lived 236Bk and 236Am more than a decade ago is frequently cited in their papers, yet the several existing compendia of isotopes do not acknowledge the existence of these species. The collaboration results include mention of observing long-lived proton-decay, of deformed spallation products undergoing secondary fusion reactions, and of hyperdeformed shapes, any of which significant topics by themselves should have attracted studies by other groups years ago. Yet this has not occurred. The collaborations arguable use of forceful expressions such as "overwhelming evidence", "clear and proven", and "impossible to refute" is neither convincing nor swaying. Extraordinary intriguing phenomena, not much selective in their measured character, are, in part, necessary for the acceptance of the collaborations interpretations of their data. A. Marinov, S. Gelberg, D. Kolb. Abnormal radioactive decays out of long-lived superand hyper-deformed isomeric states, Proc. Intl. Symp. on Exotic Nucl. Struct. 1520 May 2000, Debrecen, Hungary, pp. 341344 (2000).
A. Marinov,
S. Gelberg,
D.
Kolb.
Discovery
of
long-lived
shape
isomeric
states
which
decay
by
strongly
retarded
high-energy
particle
radioactivity,
Int.
J.
Mod.
Phys.
E
10,
185208
(2001).
A. Marinov, S. Gelberg, D. Kolb. Strongly enhanced low energy alpha-particle decay in heavy actinide nuclei and long-lived superdeformed and hyperdeformed isomeric states, Int. J. Mod. Phys. E 10, 209236 (2001).
A. Marinov.
Isomeric
states
and
uncharacterized
a
-particle
groups
in
nature,
Proc.
3
rd
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|
For completeness, we take note of the Berkeley collaboration study of 86Kr + 208Pb by Ninov et al.. Three chains terminating in 269Sg enabled observation of intermediate 281112 .Retraction of results appear in:
V.
Ninov,
K.
E.
Gregorich,
W.
Loveland,
A.
Ghiorso,
D.
C.
Hoffman,
D.
M.
Lee,
H.
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| APSIDIUM © | Created: | 2002-09-01 |
112.pdf |
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Page update: | 2004-12-05 |
![[Picture]](112_g.jpg)
![[Picture]](112_f.jpg)
![[Picture]](112_c.jpg)
