Study of Muon-Catalyzed Fusion in Ortho–Para Controlled Solid Deuterium

Recently, the applicability of Penning trap mass spectrometry has been extended to nuclides with a half-life of less than one second. The mass of ³³Ar (T _1/2=174 ms) was measured using the ISOLTRAP spectrometer with an accuracy of 4.2 keV. This measurement provided a stringent test of the Isobaric Multiplet Mass Equation (IMME) at mass number A=33 and isospin T=3/2. The fast measurement cycle that shows the way to other measurements of very-short-lived nuclides is presented. Furthermore, the results of the IMME test are displayed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Mass measurements of neutron-deficient radionuclides near the end-point of the rp-process with SHIPTRAP

Direct mass measurements of nuclides near to the supposed end-point region of the astrophysical rp-process were performed at SHIPTRAP, the Penning trap mass spectrometer at GSI Darmstadt. The masses of 24 nuclides were measured with relative uncertainties between 5 ^. 10^-8 and 2 ^. 10^-7 . Three of them, ¹⁰⁷Sb , ¹¹¹I and ¹¹²I , were determined experimentally for the first time. The data analysis and mass evaluation are presented in detail.     

Measurement of uranium and its isotopes at trace levels in environmental samples using mass spectrometry

Actinides have widely entered the environment as a result of nuclear accidents and atmospheric weapon testing. These radionuclides, especially uranium, are outstanding radioactive pollutants, due to their high radiotoxicity and long half-lives. In addition to this, since depleted uranium (DU) has been used in the Balkan conflict in 1999, there has been a concern about the possible consequences of its use for the people and environment. Therefore, accurate, precise and simple determination methods are necessary in order to evaluate the human dose and the concentration and effects of these nuclides in the environment. The principal isotopes of uranium e.g. ²³⁵U and ²³⁸U are of primordial origin and ²³⁴U present in radioactive equilibrium with ²³⁸U. ²³⁶U occurs in nature at ultra trace concentrations with a ²³⁶U: ²³⁸U atom ratio of 10⁻¹⁴. Concentrations of uranium in soil samples were determined using inductively coupled plasma mass spectrometry (ICP-MS) and isotope ratios of uranium were measured using a thermal ionisation mass spectrometer. Radioactive dis-equilibrium of ²³⁴/²³⁸U, depletion of ²³⁵/²³⁸U and significant evidence of ²³⁶U/²³⁸U were noticed in soil samples.      

Thermonuclear reaction rates from (p,n) reactions

Thermonuclear reaction rates for the temperature range 1≤T ₉≤5 have been extracted from experimentally measured (p, n) cross sections for⁴⁵Sc⁵⁰Ti,⁵¹V,⁵⁴Cr,⁵⁵Mn and⁵⁹Co nuclides below 5 MeV bombarding energy. These reaction rates are important in the build-up of medium and heavy nuclides in the stellar evolution process and nucleosynthesis. To enhance the usefulness of these reaction rates in astrophysical calculations, they have been fitted to an analytic function of temperature, valid throughout the temperature range considered here.     

Direct mass measurements of neutron-deficient 152Sm projectile fragments at the FRS-ESR facility

The FRS-ESR facility at GSI provides one of the most efficient methods for direct mass measurements. In the present experiment, exotic nuclei were produced via fragmentation of ¹⁵²Sm projectiles in a thick beryllium target at 500-600 MeV/u, separated in-flight with the fragment separator FRS, and injected into the storage-cooler ring ESR. Time-resolved Schottky Mass Spectrometry was applied for mass measurements of stored and electron-cooled bare and few-electron ions. 373 different nuclides were identified by means of the spectra of their revolution frequencies. Masses for 18 nuclides (⁸⁴Zr, ⁹²Ru, ⁹⁴Rh, ^107,108,110Sb, ^111,112,114I, ¹¹⁸Ba, ^122,123La, ¹²⁴Ce, ¹²⁷Pr, ¹²⁹Nd, ¹³²Pm, ¹³⁴Sm, ¹³⁷Eu) have been determined for the first time. Masses for ^111,112I and ¹¹³Xe have been obtained via known α-decay energies. The experiment and first results will be presented.     

Schottky Mass Measurements of Cooled Exotic Nuclei

Projectile fragments of a ²⁰⁹Bi beam were separated in flight with the fragment separator FRS and injected into the experimental storage ring ESR. In the ESR a beam containing up to about 100 different isotopes was cooled to a relative velocity spread of δv/v=10⁻⁶ by means of the electron cooler. The image currents of the ions induced in a Schottky pick-up probe at each turn were recorded. A subsequent Fast Fourier Transformation of these signals yields the revolution frequencies of the different isotopes stored in the ESR. Unknown masses of more than 150 neutron-deficient nuclides in the element range of 52≤Z≤85 have been measured directly by Schottky Mass Spectrometry and in addition more than 60 new masses have been obtained from α-decay chains. These new mass data allow the location of the one-proton dripline and the prediction of the two-proton dripline for heavy nuclides. The experimental masses are compared with different theoretical predictions. This revised version was published online in July 2006 with corrections to the Cover Date.     

Stopping, Trapping and Cooling of Radioactive Fission Fragments in an Ion Catcher Device

An ion catcher as presented in this contribution is able to create cooled and very clean singly-charged ion pulses out of a ‘hot’ beam within a very short period of time. Precision measurements on shortlived radioactive nuclides become possible. This contribution describes experiments with a ²⁵²Cf fission source at the ‘gas-cooler’ at ATLAS (Argonne Tandem Linac Accelerating System) at the Argonne National Laboratories (ANL), Argonne, USA[1]. The system consists of a gas-cell to stop and thermalize the ions, two extraction radio frequency quadrupole structures (RFQ) to separate the ions from the buffer gas and a buncher RFQ to cool and accumulate the ions. The system and its performance is investigated with two independent measurements. The transported activity was measured to determine the efficiency of the system and time of flight measurements (TOF) were performed to determine the transported masses with respect to the transported activity. This revised version was published online in July 2006 with corrections to the Cover Date.     

Mass measurements of relativistic projectile fragments in the storage ring ESR

Two experimental methods of measuring masses of exotic nuclei in the storage ring ESR are presented. Bismuth and nickel fragments were produced via projectile fragmentation, separated and investigated with the combination of the fragment separator FRS and the ESR: (i) Direct mass measurements of relativistic projectile fragments were performed using Schottky mass spectrometry (SMS), i.e., exotic nuclei were stored and cooled in the ESR. Applying electron cooling, the relative velocity spread of circulating low intensity beams can be reduced below 10⁻⁶. Under this condition a mass resolving power of up to m/Δm=6.5·10⁵ (FWHM) was achieved in a recent measurement. Previously unknown masses of more than 100 neutron-deficient isotopes have been measured in the range of 60≤Z≤84. Using known Q _α values the area of known masses could be extended to more exotic nuclei and to higher proton numbers. The results are compared with mass models and extrapolations of experimental values. In a second experiment with ²⁰⁹Bi projectiles the area of the measured masses was extended to lower proton numbers. Due to various improvements at the ESR the precision of the measurements could be raised. (ii) Exotic nuclei with half-lives shorter than the time needed for SMS (present limit: T _1/2 ≈ 5 sec) can be investigated by time-of-flight measurements whereby the ESR is operated in the isochronous mode. This novel experimental technique has been successfully applied in first measurements with nickel and neon fragments where a mass resolving power of m/Δm=1.5·10⁵ (FWHM) was achieved.     

Low-energy antimony implantation in silicon

Abstract

Antimony is known to be a donor in silicon, Low-energy implantations of Sb in Si produce very shallow profiles which have many device applications. Gibbons et al. ¹ calulated the projected ranges of Sb ion-implanted in Si, using the LSS (Lindhard, Scharff, and Schiott) method. Oetzmann et al. ² measured projected ranges and range straggling for several heavy ions in Si, Al, and Ge, using high-resolution backscattering; in the energy region of interest to us, e = 10^?2 to 10^?1, their results were about 30% higher than those reported by Gibbons et al. In the study reported here, we implanted 5 × 10¹⁴ Sb/cm² in Si at 5–60 keV, measured the resulting depth distribution by secondary ion mass spectrometry, and checked the measurements by backscattering. Our results showed the experimental projected ranges to be about halfway between those reported in the earlier studies. The discrepancies between theoretical calculations and experimental results are due not to the electronic stopping cross section, which is negligible in the range of interest here, but to the nuclear stopping power. Using a modified nuclear scattering potential given by Wilson et al.,³ we calculated the projected range distribution according to the method described by Winterbon.⁴ Our results are in very good agreement with the experimental measurements.     

A Sensitive Isotope Selective Nondispersive Infrared Spectrometer for 13CO2 and 12CO2 Concentration Measurements in Breath Samples

We present a nondispersive infrared spectrometer (NDIRS) for the measurement of the ¹³CO₂/¹²CO₂-ratio in breath samples. A commercial NDIR spectrometer for CO₂ concentration measurements in industrial process control was modified using two separate optical channels for the ¹³CO₂ and ¹²CO₂ detection. Cross interference due to overlapping absorption lines of both isotopic gases was successfully eliminated. The sensitivity of this device is ± 0.4‰ of the ¹³CO₂/¹²CO₂-ratio in a range of 2.5 to 5% of total CO₂. This is sufficient for biomedical applications. Our spectrometer is small in size, cheap and simple to operate and thus a true alternative to isotope ratio mass spectrometers (IRMS). Several biomedical applications with breath samples were demonstrated and were compared in very good agreement with IRMS.     

The Application of SF6 in the Geochemical Research

For mass spectrometric measurements of δ³¹S, pure sulphur hexafluoride was prepared quantitatively from different mineral sulphides by the reaction with elemental fluorine under pressure. The results of δ³¹S measurements on SF₆ samples were confirmed by comparison of δ³¹S values with the classical method leading to SO₂. Numerous mass spectrometric measurements of SF₆ and SO₂ with regard to the experimental conditions of the synthesis, the influence of background, memory effect, and adsorption were made. The measurements of small isotopic variations of sulphur with SF₆ has advantages in comparison to the SO₂ technique. The method described can be successfully used for routine work.     

Analysis of 13C-mixed Triacylglycerol in Stool by Bulk (Ea-IRMS) and Compound Specific (GC/MS) Methods

Abstract

This paper was presented in poster form at the 17th International Congress of Nutrition, August 27-31, Vienna. Austria (Annals of Nutrition & Metabolism 2001; 45(Suppl.1):349). Some of the data were also presented in poster form at the British Society of Gastroenterology Meeting, March 18-21, Glasgow, UK (Gut 2001; 48(Suppl.1):A91).

The ¹³C-mixed triacylglycerol (MTG) breath test is used to measure intraluminal fat digestion. In normal digestion. 20–40% of the ingested ¹³C label is recovered in breath CO₂. We aimed to identify the proportions of ingested label excreted in stool, as well as breath following ingestion of ¹³C-MTG by children with impaired exocrine pancreatic function and healthy controls. ¹³C enrichment of breath samples was measured by continuous flow isotope ratio mass spectrometry (IRMS) and cumulative percent dose recovered (cPDR) in 10 h was calculated. Total ¹³C of a faecal fat extract from each stool was measured by elemental analyser-IRMS, and ¹³C enrichment and concentration of the TBDMS derivative of octanoic acid was measured by GC/MS after hydrolysis of the fat extract. Stool 5-day cPDR was calculated. Mean breath cPDR was 35%. Mean cPDR in stool by combustion-IRMS and GC/ MS, respectively, was 0.8% and 1.0%. Therefore, the remaining 64% of the ¹³C label must remain in the body and variability in breath cPDR is due to postabsorptive rather than predigestive factors.     

I. Spectroscopic Investigation of Charge Transrer Complexes of Oxime Intermediates Prepared from Some Pharmaceutical Carbonyl Compounds

Spectroscopic studies on the reaction of iodine as π-acceptor and chloronil as π-acceptor with oxime intermediates prepared from certain pharmaceutical carbonyl compounds are reported. These compounds include Δ^1,4 -3-corticosteroids (prednisone, prednisolone, dexamethasone), Δ⁴-3-ketosteroids (progesterone, testosterone propinate, nandrolone phenpropionate), griseofulvin, carvone, and menthone. The spectroscopic techniques applied are IR, far IR spectroscopy, H¹, C¹³NMR, mass spectra (MS), fast atom bombardment mass spectra (FABMS), electron spin resonance (ESR) and microanalysis of the reaction products. The structure elucidation studies of these complexes confirmed the charge transfer complex (CTC) formation.     

Theoretical calculation of of B-like ions： photoionization cross sections N^2＋, O^3＋ and F^4＋

There can be found some notable discrepancies with regard to the resonance structures when R-matrix calculations from the Opacity Project and other sources are compared with recent absolute experimental measurements of Bizau et al [Astron.Astrophts.439 387(2005)] for B-like ions N2+,O3+ and F4+.We performed close-coupling calculations based on the R-matrix formalism for the photoionizations of ions mentioned above both for the ground states and first excited states in the near threshold regions.The present results are compared with experimental ones given by Bizau et al and earlier theoretical ones.Excellent agreement is obtained between our theoretical results and the experimental photoionization cross sections.The present calculations show a significant improvement over the previous theoretical results.     

Spectroscopic Investigation of the Antazoune-p-chloranilic Acid Reaction Product

Spectroscopic studies on the reaction of p-chloranilic acid with antazoline base are reported. These include UV/VIS and IR spectrophotoraetry, electron spin resonance (ESR) and nuclear magnetic resonances (¹H-NMR & ¹³C-NMR). The results reveal that the antazoline-p-chloranilic acid product is an ion pair salt rather than a charge-transfer complex.     

High-accuracy mass spectrometry with stored ions

Like few other parameters, the mass of an atom, and its inherent connection with the atomic and nuclear binding energy is a fundamental property, a unique fingerprint of the atomic nucleus. Each nuclide comes with its own mass value different from all others. For short-lived exotic atomic nuclei the importance of its mass ranges from the verification of nuclear models to a test of the Standard Model, in particular with regard to the weak interaction and the unitarity of the Cabibbo–Kobayashi–Maskawa quark mixing matrix. In addition, accurate mass values are important for a variety of applications that extend beyond nuclear physics. Mass measurements on stable atoms now reach a relative uncertainty of about 10^-11${10}^{-11}$. This extreme accuracy contributes, among other things, to metrology, for example the determination of fundamental constants and a new definition of the kilogram, and to tests of quantum electrodynamics and fundamental charge, parity, and time reversal symmetry. The introduction of Penning traps and storage rings into the field of mass spectrometry has made this method a prime choice for high-accuracy measurements on short-lived and stable nuclides. This is reflected in the large number of traps in operation, under construction, or planned world-wide. With the development and application of proper cooling and detection methods the trapping technique has the potential to provide the highest sensitivity and accuracy, even for very short-lived nuclides far from stability. This review describes the basics and recent progress made in ion trapping, cooling, and detection for high-accuracy mass measurements with emphasis on Penning traps. Special attention is devoted to the applications of accurate mass values in different fields of physics.     

Atomic 6p-Tl0 centers in ferroelectric Rb2ZnCl4 crystals

Abstract

Several Tl⁰ (6s²6p ¹)-type paramagnetic centers, produced by low temperature X-ray irradiation, were observed and studied by electron spin resonance (ESR) in the orthorhombic ferroelectric phase of thallium doped Rb₂ZnCl₄ crystals. The centers were formed by electron trapping at Tl⁺ ions localized substitutionally at Rb⁺ sites. The number and properties of the observed centers account for the tripling of the unit cell in the ferroelectric phase.     

Coherently Precessing Spin Structure in 3He-B High-Resolution Quantum Amplifier

We present results of the study of surface oscillation modes of coherently precessing nuclear spins in the superfluid ³He-B known as a homogeneously precessing domain (HPD). HPD represents the first macroscopic experimental manifestation of magnetic superfluidity phenomenon. The measurements showed that HPD is extremely sensitive to longitudinal perturbations and it behaves as tuned (by magnetic field gradient) quantum amplifier that allows to measure very small changes of magnetic field with very high relative resolution, of the order of 10^-7.     

The 2D {P} Spin-Echo-Difference Constant-Time [C, H]-HMQC Experiment for Simultaneous Determination of JH3′P and JC4′P in C-Labeled Nucleic Acids and Their Protein Complexes

A two-dimensional {³¹P} spin-echo-difference constant-time [¹³C, ¹H]-HMQC experiment (2D {³¹P}-sedct-[¹³C, ¹H]-HMQC) is introduced for measurements of ³J_C4′P and ³J_H3′P scalar couplings in large ¹³C-labeled nucleic acids and in DNA–protein complexes. This experiment makes use of the fact that ¹H–¹³C multiple-quantum coherences in macromolecules relax more slowly than the corresponding ¹³C single-quantum coherences. ³J_C4′P and ³J_H3′P are related via Karplus-type functions with the phosphodiester torsion angles β and ε, respectively, and their experimental assessment therefore contributes to further improved quality of NMR solution structures. Data are presented for a uniformly ¹³C, ¹⁵N-labeled 14-base-pair DNA duplex, both free in solution and in a 17-kDa protein–DNA complex.