Chemical investigations of Element 108, Hassium (Hs) Page: 4 of 7
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place. Hs was then transported through a PFA Teflon tube to the detection device in the form of
HsO4. This technique was named In-situ Voaltilization and On-line detection (IVO) . The
efficiency of IVO to forward formed short-lived Os isotopes to the detection system was
measured to be 60-90% in test experiments. The method of gas phase adsorption
thermochromatography  was used to measure the deposition temperature of HsO4 on the
surface of a chromatography column. An on-line thermochromatography system has been
developed at Berkeley  and an improved version called the Cryo-On-Line Detector (COLD)
[14,18] has been built at the Paul Scherrer Institute in Switzerland. The chromatography column
consisted of 12 pairs of PIN-diodes (Area: 1x3 cm2 each) forming a narrow rectangular channel
with a spacing of 1.6 mm. PIN-diodes are suitable for registering a-particles and fission
fragments. By means of a thermostat and a vessel containing LN2, a temperature gradient from -
20 to -170 C was established along the column. Deposition of HsO4 was expected at a
temperature lying between these two values. The overall efficiency of the IVO-COLD system
Table 1: Observed correlated decay chains. Given are the energies of the observed events and the
time difference between an event and the preceding one. The setup used did not allow
for determining the lifetime of the mother events. Fission events are marked with an
asterisk. Two asterisks identify SF events where only one fragment was registered. nR is
the probability of a chain to be of random origin not related to the decay of a Hs isotope.
Det. indicates the detector unit in which the chain was observed. The last column gives
the isotope to which the decay chain was assigned to.
[ e ] At2 [s] E At3 [s] E ] At4 [s] nR Det. Isotope
K [MVeV] [MeV] [MeV] [MeV]
1 9.16 8.66 25.665 94+93* 0.199 <8x10-6 2 270Hs
2 9.18 8.69 4.409 8.50 2.365 8.21 55.567 <2x10-6 3 269Hs
3 - 8.72 - 53** 3.124 <2x10~4 4 269/270Hs
8.97 8.64 11.911 94+92* 1216 15x10~5 4 270Hs
5 9.10 8.68 9.325 94+85* 7.920 <7x10-6 3 269Hs
6 8.88 8.90 17.078 8.50 0.846 17x10~5 3 V269Hs
7 9.14 - - 108** 42.615 I<4x10 4 3 269/270Hs
Data was acquired during 64.2 h and a total of 1018 particles passed through the target. The
obtained a-spectra were very clean and exhibited only a-particle lines of 2m1At and 219,220Rn and
their daughters. 219Rn was added to the carrier gas to allow for an on-line calibration of the
detectors. The correlation analysis revealed a total of seven correlated decay chains  which
are given in Table 1. The distribution of Hs and Os in the temperature gradient tube is shown in
Figure 2 which contains the merged thermochromatogram of 17Os04 (T12: 19 s) and the events
attributed to the decay of a Hs isotope.
The enthalpy of adsorption AHads of the species on the column surface material (silicon nitride,
Si3N4) was extracted from the measured deposition distribution by using Monte Carlo
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Dullmann, Christoph E. Chemical investigations of Element 108, Hassium (Hs), article, July 3, 2003; Berkeley, California. (digital.library.unt.edu/ark:/67531/metadc883923/m1/4/: accessed June 22, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.