The chemical states of tellurium produced by spontaneous fission of252Cf

The distribution of the chemical states of tellurium isotopes produced by²⁵²Cf spontaneous fission, collected separately in the matrixes of NaCl, Kl, NaF, CH₃COONa·3H₂O, Na₂SO₄ and NaNO₃ crystals have been investigated. Two chemical states of tellurium isotopes maintained in these matrixes are Te(IV) and Te(VI). The relationships between the distribution of the chemical states of tellurium isotopes and the produced mode of tellurium, the chemical properties of collection matrixes, the time for collecting fission fragments are studied and the possible mechanism of the interactions of the fission products and the matrixes is discussed. The results show that the distribution of chemical states of tellurium isotopes depends on the chemical properties of the collection matrixes mainly.     

Chemical states of iodine produced by the spontaneous fission of252Cf

The distributions of the chemical states of¹³¹I,¹³²I,¹³³I,¹³⁴I and¹³⁵I produced by the spontaneous fission of²⁵²Cf were investigated by the method of fractional precipitation separation in 6M NH₄OH solution followed by measurement of the X-ray spectrum of the samples with a Ge(Li) detector. The iodine fission fragments were separately collected in the matrices of NaNO₃, NaCl, dehydrated sodium sulfate, CH₃COONa·3H₂O, Na₃H₂IO₆, KI and NaIO₃ crystals. The results showed that the distribution of the chemical states was the function of the collection time, the nature of matrix materials and the type of iodine isotopes. The relative amount of the reduced states of¹³⁴I decreased with the increase of collection time in the matrix of NaNO₃. The ratio of the amount of reduced states to the total amount of the¹³⁴I was the highest (50.4%) in NaCl matrix and the lowest (9.4%) in Na₃H₂IO₆ matrix. The relative quantities of reduced states of¹³⁵I were the highest (58.5% and 97.7%) and that of¹³⁴I were the lowest (16.9% and 63.1%) in matrices of NaNO₃ and NaCl, respectively.     

Absolute determination of the spontaneous fission yield of252Cf by radiochemical method

The distribution of mass in the spontaneous fission of²⁵²Cf has been investigated by the radiochemical determination of the absolute fission yields for 35 mass chains. A summation of the mass-yield curve gives a summed value of 199.4% which is in very good agreement with the value of 200% in fission. The mean masses of the light and heavy group are located at 106.39 and 141.82, respectively. The average number of neutron per fisson is 3.79±0.12. The peak-to-valley ratio is larger than 370. The width at one tenth of the maximum of the light and heavy group are 26.7 and 26.8 mass number, respectively. A comparison of previous investigators has resulted in recommended yields for 35 mass chains.     

Cumulative yields of short-lived xenon isotopes in the spontaneous fission of252Cf

Cumulative yields of short-lived xenon isotopes^137,138,139Xe have been determined in the spontaneous fission of²⁵²Cf, using a fast radiochemical separation method followed by gamma spectrometry. Xenon-137 yield is reported for the first time. The measured cumulative yields are converted to chain yields assuming normal charge distribution systematics for comparision with the literature data.     

Cumulative yields of short-lived isotopes of barium in the spontaneous fission of252Cf

Cumulative yields of short-lived/barium isotopes^{139, 141, 142}Ba have been determined in the spontaneous fission of²⁵²Cf, using fast radiochemical separation and gamma-ray spectrometry.¹⁴²Ba yield is reported for the first time. The measured cumulative yields are converted to chain yields, assuming normal charge distribution systematics for comparision with the literature data.     

Cumulative yields of the short-lived ruthenium isotopes in the spontaneous fission of252Cf

⁶⁷Ga is produced by the⁶⁶Zn(d,n) reaction at 9 MeV bombarding energy. Deuterons of about 30 A obtained from the T-11 Tandem accelerator are used to bombard targets of natural Zinc prepared by electroplating onto thick copper disks. Radiochemical separation of gallium is performed by using a cation exchange column. The optimum conditions for an efficient separation are given in detail.     

Cumulative yields of127gSn and128Sn in the spontaneous fission of252Cf

The potteries found on the Tremiti Isles (Italy, Adriatic Sea) have been characterized through their trace elements content. The goal of the work was to find out the number of ore deposits that supplied the clay used to manufacture the pottery. Neutron activation analysis has been employed for trace elements content determinations; the results have been statistically evaluated, clusterized and discussed.     

Use of252Cf for elemental analysis

The neutron sources based on the²⁵²Cf isotope and having relatively long half-lives and the highest specific neutron yields compared with other ampouled sources are proved to be the most convenient for use in industrial analytical laboratories situated far from the basic nuclear centers. Research making use of californium sources is currently carried out in a number of nuclear centers of the USSR, including the Institute of Nuclear Physics of the Uzbek Academy of Sciences, where a great amount of work have been done on verification of practical use of Cf sources of various activity in different branches of industry, first of all, in geology and mining industry.     

Combined liquid chromatography time-of-flight mass spectrometry: An application of 252Cf fission fragment induced desorption mass spectrometry

A ²⁵²Cf fission fragment induced desorption mass spectrometer has been coupled on-line to a high-performance liquid chromatograph. The polar effluent (MeOH? H₂O) is introduced directly into a rough vacuum stage, where a thin sample of non-volatile compounds is collected in a vacuum-drying process (<1 cm³ min^?1). The interface which spans the difference in operating pressure between the collection site and the ion source consists basically of a sample changing disk. Twelve discrete samples are collected consecutively and analysed, typically one per minute. The system has been tested for the quantitative analysis of some antitumor drugs in serum using homologous compounds as internal standards.     

Transformations of DI(phosphinylsulfide) complexes of Pd(II) during bombardment with fission products of252Cf

Transformations of chelate complexes of Pd(II) with di(phosphinylsulfide) during bombardment with fission products of²⁵²Cf have been investigated for the first time using plasma desorption mass spectrometry. Disproportionation of Pd(II) to Pd(I) and Pd(III) was observed for a number of the complexes studied. Formation of polynuclear complexes in the gas phase was observed.L. V. Pisarzhevskii Institute of Physical Chemistry, Ukraine Academy of Sciences, Ukraine, 252039 Kiev, Prospekt Nauki, 31. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 32, No. 3, pp. 172–176, May–June, 1996. Original article submitted July 13, 1995.     

Nuclear charge distribution in the spontaneous fission of252Cf: Determination of fractional cumulative yields of133mTe and133gTe

The fractional cumulative yields (FCY) of^133mTe and^133gTe in the spontaneous fission of²⁵²Cf were measured for the first time by a radiochemical method. The values ofFCY are 0.533±0.014 and 0.291±0.042 for^133mTe and^133gTe, respectively. The isomeric state to ground state fractional independent yield (FIY) ratio of¹³³Te,R, was found to be 3.5. The root-mean-square angular momentum of the primary fragment corresponding to the fission product¹³³Te, Jr.m.s.=8.8h, was estimated according to a simple one-parameter statistical model. The fractional cumulative yields from this work together with other literature data in the mass region A=131–141 are compared with the normal yields given by the empiricalZ _p model by Whhl. It suggests that both theN=82 neutrons shell and nucleus pairing effects are not apparent for the spontaneous fission of²⁵²Cf.     

In situ activation analysis of marine sediments with252Cf

A seabed nuclear probe has been developed which permits the measurement of up to 33 elements at the parts per thousand to parts per million levels in continental shelf areas. The probe consists of a neutron irradiation source,²⁵²Cf, which neutron activates the elements in the minerals of interest. These resulting radioactive elements emit characteristic gamma radiation which is analyzed in situ in 2- to 10 min counting intervals with a Ge(Li) detector system. Details of the irradiation source, the Ge(Li) detector, and spectra taken in situ in a marine environment are discussed with respect to the detection of the minerals at concentrations of economic interest.     

In vivo analysis for nitrogen using a252Cf source

A set up forin vivo determination of nitrogen has been built. Phantoms containing different amounts of nitrogen have been measured as well as a volunteer in a pilot study. A total body protein content of 18.8 kg was calculated, to be compared with 17.0 kg estimated from potassium measurements.     

Neutron activation analysis with PE moderated252Cf neutron source

The 1.369 MeV -rays emitted from²⁴Na²⁴Mg+^–+ after²³Na(n,)²⁴Na reaction were counted by high purity germanium (HPGe) detector and the half-life of²⁴Na was derived. This process was simulated by Monte Carlo Neutron and Photon Transport Code (MCNP-4A).²⁵²Cf neutron source was moderated by a polyethylene (PE) cylinder to increase the cross section of neutron absorption reaction and to decrease the biological hazard. NaCl powder of 20 cm³ and 40 cm³ volume in cylindrical polypropylene capsules were irradiated by the neutrons passed through the moderator. MCNP-4A was used to determine the optimum size of PE moderator, to assume the realistic geometry of the HPGe detector, and to assume the absolute efficiencies of the detector. The count rates for 1.369 MeV -rays in the HPGe detector were calculated by MCNP-4A for 20 cm³ and 40 cm³ NaCl. The accumulated counts calculated tumed out to be higher than those actually measured by 31% with a relative error of 3%. The half-life of²⁴Na measured within 4% and 1% for 20 cm³ and 40cm³ NaCl agrees with that of the reference. So, we can say that the result of MCNP-4A has about 30% of accuracy and 3% of precision in simulating the neutron activation analysis.     

Yields of rare earth fission products in the spontaneous fission of californium-252

Cumulative fission yields of rare earth isotopes have been determined in the spontaneous fission of²⁵²Cf by fast radiochemical separation and gamma-ray spectrometry. The determined yield values are compared with the available literature data. The yield values for¹⁴⁷Nd,¹⁵¹Nd and¹⁵¹Pm differ from the reported values. The yield for¹⁴⁵Ce is determined for the first time.     

On-target deuteration technique in time-of-flight 252Cf plasma desorption mass spectrometry

A new on-target deuteration technique in plasma desorption mass Spectrometry (PDMS) is proposed, involving replacing labile hydrogen atoms in a molecule with deuterium atoms. This technique is very simple and allows direct comparison of spectra before and after deuteration for the same probe. The utility of the deuteration procedure in PDMS has been demonstrated in obtaining additional information on the structure of a molecule and its fragments and on the mechanism of quasi-molecular ion formation.