Evidence for the existence of long-lived neutron-deficient isotopes has been found in a study of naturally-occurring Th using inductively coupled plasma-sector field mass spectrometry. They are interpreted as belonging to the recently discovered class of long-lived high spin super-and hyperdeformed isomers.In recent years, long-lived high spin super-and hyperdeformed isomeric states with unusual radioactive decay properties have been discovered in heavy and very heavy nuclei [1][2][3][4] . This discovery motivated us to perform a search for naturally-occurring long-lived isomeric states. (Up to now there is only one such isomeric state known, namely the 75.3 keV excited state in 180 Ta with a half-life of >1.2x10 15 y (ref. 5 )). Madagascan monazite and commercially available Th and U standard solutions were studied using different mass spectrometers, including an accelerator mass spectrometer. In the present paper we present the results obtained with pure Th standard solutions and also in one case with a monazite digest solution, using inductively coupled plasma-sector field mass spectrometer (ICP-SFMS).The instrument was an Element2 (Thermo-Electron, Bremen, Germany). The predefined medium resolution mode of m/∆m = 4000 (10% valley definition) was used throughout the experiments so as to separate atomic ions from interfering molecular ions with the same mass number. The sensitivityenhanced setup of the instrument was similar to that described in Ref.6 where a capacitive decoupling system and high-performance "X" skimmer were used, providing sensitivity for 232 16 O + peaks. Two 1000 mg l -1 Th stock solutions "A" and "B" from two manufacturers, Inorganic Venture and Customer Grade, were obtained from LGC Promochem AB (Borås, Sweden). Complete elemental screening was performed on both solutions to assess the impurity concentration levels PDF created with pdfFactory trial version www.pdffactory.com 2 The solutions were analyzed during three separate sessions: May 25, October 5, and November 6, 2005. A range of about 0.2 mass unit was scanned in each measured spectrum. This range was divided into approximately 60 channels. During the first session, masses from 210 to 269 were analyzed with an integration time per channel of 0.6 sec. During the second and third sessions, selected mass regions (where some indication of unidentified signals had been detected) were measured using an integration time per channel of 3 and 12 sec, respectively. Instrumental sensitivity varied significantly among runs as a result of matrix effects caused by the introduction of highly concentrated solutions into the ICP source. During the first session, the monazite digest (1000 mg monazite l -1 ) and Th solution A (diluted to 20 mg Th l -1 ) were scanned once. (The Th content in the monazite was approximately 2%. The contents of typical rare earth elements in it, like Ce, Dy and Er, were about 5%, 0.05% and 0.02%, respectively.) During the second session, 20 mg l -1 of Th A and B solutions spiked with 2 µg l -1 Bi were studied and eac...

Arsenic contamination in the environment (i.e. surface, well and tube-well water, soil, sediment and rice samples) of central India (i.e. Ambagarh Chauki, Chhattisgarh) is reported. The concentration of the total arsenic in the samples i.e. water (n = 64), soil (n = 30), sediment (n = 27) and rice grain (n = 10) were ranged from 15 to 825 microg L(-1), 9 to 390 mg kg(-1), 19 to 489 mg kg(-1) and 0.018 to 0.446 mg kg(-1), respectively. In all type of waters, the arsenic levels exceeded the permissible limit, 10 microg L(-1). The most toxic and mobile inorganic species i.e. As(III) and As(V) are predominantly present in water of this region. The soils have relatively higher contents of arsenic and other elements i.e. Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Ga, Zr, Sn, Sb, Pb and U. The mean arsenic contents in soil of this region are much higher than in arsenic soil of West Bengal and Bangladesh. The lowest level of arsenic in the soil of this region is 3.7 mg kg(-1) with median value of 9.5 mg kg(-1). The arsenic contents in the sediments are at least 2-folds higher than in the soil. The sources of arsenic contamination in the soil of this region are expected from the rock weathering as well as the atmospheric deposition. The environmental samples i.e. water, soil dust, food, etc. are expected the major exposure for the arsenic contamination. The most of people living in this region are suffering with arsenic borne diseases (i.e. melanosis, keratosis, skin cancer, etc.).

Evidence for the existence of long-lived isotopes with atomic mass numbers 261 and 265 and abundance of (1-10)x10 −10 relative to Au has been found in a study of natural Au using an inductively coupled plasma -sector field mass spectrometer. The measured masses fit the predictions made for the masses of 261 Rg and 265 Rg (Z=111) and for some isotopes of nearby elements. The possibility that these isotopes belong to the recently discovered class of long-lived high spin superand hyperdeformed isomeric states is discussed.

Evidence for the existence of a superheavy nucleus with atomic mass number A=292 and abundance (1-10)x10 -12 relative to 232 Th has been found in a study of natural Th using inductively coupled plasma-sector field mass spectrometry. The measured mass matches the predictions 1,2 for the mass of an isotope with atomic number Z=122 or a nearby element. Its estimated half-life of t 1/2 ≥10 8 y suggests that a long-lived isomeric state exists in this isotope. The possibility that it might belong to a new class of long-lived high spin super-and hyperdeformed isomeric states is discussed. 3-6The question "how heavy can a nucleus be" is a fundamental problem in nuclear physics. The mass M A of an atom is equal to:where M H and M n are the masses of the hydrogen atom and the neutron, respectively, and BE is the binding energy of the nucleus. The binding energy per nucleon (BE/u) of stable nuclei has a broad maximum around A ≈ 60, with a value of 8.7 MeV/u, which falls monotonically to about 7.6 MeV/u at Th and U. 19 The predicted BE/u values for the superactinide nuclei are around 6.9 MeV/u. 1,2,20,21 Therefore, masses of superactinide isotopes are higher than, and resolvable from, the masses of all molecules with the same mass number, except for multihydrogen-containing molecules. This is seen in Fig. 1 In principle, natural minerals like monazite, which is the usual source material for Th, would be the most promising materials to study. However, background was the main obstacle when looking for isotopes with relative abundance of (1-10)x10 -11 in natural materials. 10Therefore, purified natural Th was used in our measurements.In the present work, we performed accurate mass measurements for masses 287 to 294 in Th solutions. Evidence was obtained for the existence of an isotope with a mass that matches the predictions for atomic mass number 292 and Z around 122. Here we describe this observation.The experimental procedure was similar to that described earlier. 10 Inductively coupled plasma-sector field mass spectrometry (ICP-SFMS) was used for the experiments. The ICP-SFMS is an Element2 (Finnigan, Thermo-Electron, Bremen, Germany). In this instrument, a solution of the material to be studied is introduced into a high temperature (6000-8000 K) plasma source. At these temperatures, predominantly atomic species are present. Molecular ions are produced after the source, mainly by interaction with oxygen and hydrogen ions from the solution. The predefined medium resolution mode, m/∆m = 4000 (10% valley definition), was used throughout to separate atomic ions from molecules with the same mass number. The sensitivity-enhanced set-up of the instrument was similar to that described in Ref. During the first session, masses from 287 to 294 were analysed using the Th solutions with an integration time of 1 s channel -1 , and these measurements were made three to five times each. In one spectrum, two events were observed with a solution produced by CustomerGrade (from LGC Promochem AB, Borås, Sweden) at a mass that fits the predic...

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