High-resolution Magnetic Spectrometer Research Articles

New high-resolution inductively coupled plasma mass spectrometry technology applied for the determination of V, Fe, Cu, Zn and Ag in human serum

Spectral interferences are a limiting factor in quadrupole inductively coupled plasma mass spectrometry (quadropole ICP-MS). Most of these interferences disappear when a high-resolution magnetic sector mass spectrometer is coupled to the ICP ion source. In this paper, results of the first analyses with a new type of a high resolution ICP-MS instrument are shown. The instrument is a commercially available machine (Finnigan MAT, Bremen, Germany) offering standard resolution settings of 300, 3000 and 7000 (M/ΔM, 10% valley definition). With a resolution setting of 3000, V, Fe, Cu and Zn were determined in a second generation human serum reference material. Human serum diluted 4- to 8-fold was measured. The results, expressed as concentrations (µg g–1)[standard deviation (SD) in parentheses] in the freeze dried material for Fe, 23.6 (0.8); Cu, 10.7 (0.2); and Zn, 8.2 (0.8) are in good agreement with the certified values. The very low V content is not certified. In the high-resolution spectrum the V peak was measured next to an approximately 1000 times higher 35Cl16O peak and a concentration of 0.83 ng g–1, SD 0.09 ng g–1 was found, which confirms an earlier radiochemical neutron activation value of 0.67 ng g–1, SD 0.05 ng g–1. For the determination of Ag using the low resolution (300) setting a limit of detection (LOD) of 4.3 pg ml–1 in the solution was found. The instrumental LOD is 10–100 times lower and the experiments show that an investigation of blanks and methods of dealing with memory effects will be necessary before full use can be made of the sensitivity of high resolution ICP-MS.

Shimming of high resolution magnetic spectrographs: a new analytical and numerical method

A new analytical and numerical method for shimming high resolution magnetic spectrometers is presented. In this method the effect of the shims on the high order corrections are numerically simulated, and their detailed shapes and locations are determined by numerical iterations. A practical application to the SPEG spectrometer at GANIL is presented.

Positron mass spectrometer design using crossed electric and magnetic fields.

Method of comparing the positron mass with the electron mass by using crossed fields is discussed on the basis of the relativistic calculation to the second order. Remodeling of a high resolution magnetic β-ray spectrometer into a positron-electron mass spectrometer is proposed. The crossed fields in the β-ray spectrometer equipped with a pair of cylindrical electrodes gives the mass dispersion of 1.3 μm/ppm at the optical circle of 0.75 m radius. Simulated peak profiles are presented for the monochromatic source of electrons or positrons and the β-ray source that emits them simultaneously in the continuous distribution.

A low energy, high-luminosity, high-resolution double-focusing magnetic beta-ray spectrometer for measuring neutrino rest mass

A spectrometer is described which was reconstructed from an electromagnetic isotope separator. The characteristics of the modified spectrometer, such as stability background resolving power, and luminosity have been tested and determined showing a momentum resolution of 0.8% and luminosity of 0.12 cm/sup 2/ for the 16-23 keV region.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Intrinsic reflection asymmetry in 225Ra: Additional information from a study of the α-decay scheme of 229Th

The level structure of 225Ra has been studied by measuring the radiations associated with the α-decay of 229Th. These measurements include α- and γ-singles spectra, and αγ-, αe −-, and γγ-coincidence measurements. The α-spectra were measured with a high-resolution magnetic spectrometer and Si surface-barrier detectors, the γ-ray spectra with Ge and Ge(Li) semiconductor detectors and the electron spectra with a Si(Li) detector. Chemically purified and isotope-separated sources were used for various experiments. These data provide the energies and intensities for 20 α-branches and for ~87 γ-rays. From this information and previous e − spectrograph measurements, ~81 γ-rays are placed in a level scheme involving 22 excited states below 400 keV. Twenty of these excited states (excluding only tentative levels at 203 and 248 keV) can be assigned as members of four bands having K π = 1 2 + (ground state), 1 2 − (55.1 keV) , 3 2 + (149.9 keV) and 5 2 + (236.7 keV) . It is found necessary to include an additional alternating term ( B 1) in the rotational energy formula to adequately fit the energy spacings within the K = 1 2 bands. This approach yields decoupling parameters of opposite sign for these two bands whose absolute values are closer to each other than previously deduced, which has relevance to their interpretation as being a parity doublet. We propose a band structure for the 3 2 + band at 149.9 keV that is significantly different from earlier proposals. Under this proposal, the energy-level spacings depart substantially from a simple I( I + 1) pattern. No conclusive evidence has been found for the presence of a K π = 5 2 − band which could be the parity-doublet partner of the well established “favored” 5 2 + band at 236.7 keV. According to the predictions of models which include stable octupole-deformed nuclear shapes, the members of such a 5 2 − band will be fed by α-transitions having relatively small hindrance factors; and they should, consequently, have been observed. Although the existence of reflection-asymmetric shapes in 225Ra is an open question at present, the bulk of the available evidence on this nuclide can be accounted for, at least qualitatively, by the hypothesis that it possesses a static octupole-deformed shape. However, the nonobservation of the expected K π = 5 2 − band and the large difference in the α-hindrance factors of the spin- 7 2 members of the K π = 1 2 + and 1 2 − bands represent potential problems for this interpretation which need to be studied further.

Alpha-transfer study of 23Na

Abstract The reaction 19 F( 6 Li, d) 23 Na has been studied at a beam energy of 34 MeV using a high resolution magnetic spectrometer. A total of 36 states in 23 Na have been observed in the range E x = 4–13MeV and deuteron angular distributions obtained for 26 states. Compound processes accounted for less than 10% of the forward angle cross section in most instances. Finite-range distorted-wave Born approximation calculations have been performed and compared with the data. The calculations reproduced the observed angular distributions well, allowing relative α-particle spectroscopic factors to be extracted and several new or improved spin assignments to be made. The 6 Li- 19 F optical potential was derived from elastic scattering data obtained in the present work. The results are discussed with reference to the rotational structure of 23 Na.

Search for states using the knock-out reaction at 600 MeV/c

Abstract The knock-out reaction A( p , p)X has been used to search for narrow p -nucleus states. The experiment was performed using the 600 MeV/ c antiproton beam at LEAR and the high-resolution and large-acceptance magnetic spectrometer SPES II. The A -dependence of the annihilation-induced proton spectra has been studied on 2 H, 6 Li, 12 C, 63 Cu, 208 Pb and 209 Bi. The quasi-free elastic p p scattering observed in the lighter targets, and the comparison with the free p p scattering, also observed in this experiment, determine an effective proton number N eff for 1s- and 1p-shell protons. No evidence for narrow bound or resonant p -nucleus states could be found. Upper limits for their production are one order of magnitude lower than certain theoretical predictions, but consistent with the properties of the p -nucleus interaction, as established from recent elastic and inelastic scattering as well as from studies of antiprotonic atoms.

Simultaneous depth profiling of constituents and impurities by elastic proton scattering in amorphous hydrogenated silicon films

Depth profiles of various constituents and impurities of thin films were obtained simultaneously by a nuclear coincidence method. The energy spectrum of elastically scattered 12 MeV protons, measured by a high-resolution magnetic spectrometer, was used for constituent identification and total content determination. Constituents of interest were selected by software pulse height discrimination and their depth profiles were obtained from the recoil energy spectrum, measured by a surface barrier detector telescope. Thin films of Teflon, of carbon, and of amorphous hydrogenated silicon were measured. The best possible depth resolution is about 20 nm for carbon and is limited by the beam energy spread and the energy resolution of the solid state detectors.

The oxford MDM-2 magnetic spectrometer

A new high resolution magnetic spectrometer — the Oxford MDM-2 spectrometer — has been designed, installed and tested. The layout of the magnetic elements is in the order: entrance sextupole and multipole, gradient-field dipole and exit multipole. The device has a “normal” focal plane, and the 1.6 m radius dipole magnet has a maximum mass-energy product of 315 MeV amu. At the maximum solid angle of 8 msr, the ratio of energies that can be accepted by the spectrometer ( E max/ E min) is 1.31. Precide measurements have been performed on the magnetic elements. The dipole magnet has very low hysteresis and field integral errors that amount to less than 1 part in 10 4. After some in situ modifications the field distributions of the magnets closely approximated the original design specifications. On-line tests with various ion-beams have revealed the optimum setting for each element. These are close to theoretical predictions from the program RAYTRACE, incorporating the parameterised results of the magnetic measurements. An aberration limited resolution ( E/ ΔE) of greater than 3000 has been observed at 8 msr solid angle.

Study of the radiative decay K+--> micro+ nu gamma.

The radiative decay K/sup +/..--> mu../sup +/..nu gamma.. has been studied by a high-resolution magnetic spectrometer combined with a NaI(Tl) photon detector system. The momentum spectrum of muon from this decay mode was measured in the region 214.5

Search for antiproton-nucleus states with (p̄p) reactions

We have studied (p̄, p) reactions on 12 C, 63 Cu, and 209 Bi to search for possible nuclear states formed ny antiprotons and nuclei. The experiments used the 180 MeV antiproton beam from LEAR, and the high-resolution magnetic spectrometer, SPES II, to detect the outgoing protons. No evidence of antiproton-nucleus states was found. The gross features of the proton spectra are reasonably well described by intranuclear cascade model calculations, which consider proton emission following antiproton annihilations in the target nucleus.

Search for a Neutral Boson in a Two-Body Decay ofK+→π+X0

The momentum spectrum of the ${\ensuremath{\pi}}^{+}$ in stopping ${K}^{+}$ decays was measured by use of a high-resolution magnetic spectrometer to search for a discrete peak due to a neutral boson ${X}^{0}$ in a two-body decay ${K}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{X}^{0}$. An upper bound of the branching ratio $R({K}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{X}^{0})$ is presented for the mass range of ${X}^{0}$ from 10 to 300 MeV/${\mathit{c}}^{2}$.

Modifications to an incos data system

Several extensions and modifications have been made to our Finnigan MAT INCOS data system. All are compatible with MSDS level 3.1 Revisions B or C and are in regular use with our dual terminal, dual acquisition system. The system is interfaced to quadrupole and high resolution magnetic mass spectrometers, as well as to another minicomputer.

High resolution spectroscopy of 102Ru(d, p) 103Ru and 104Ru(p, d) 103Ru reactions

The high resolution magnetic spectrometer BIG KARL was used to investigate the low-lying states of 103Ru by 102Ru(d, p) and 104Ru(p,d) reactions at E d = 45 MeV and E p = 29 MeV. The resolution of ΔE E = (1.7–2.5) × 10 −4 was sufficient to separate most of the known states up to E x = 1 MeV excitation energy. For these levels differential cross sections have been measured in the range of θ lab = 4°–43°. A DWBA analysis has been employed in order to determine orbital angular momenta and obtain spectroscopic factors. These were used to make a number of tentative spin and parity assignments. In addition several weakly excited states in 103Ru could be identified and excitation energies have been determined to about ±2 keV.

Data Acquisition and Analysis on the High Resolution Magnetic Spectrometers at LAMPF

The data acquisition and analysis system for LAMPF'S high resolution magnetic spectrometers, HRS and EPICS, consists of two on-line PDP-11/45 computers and an off-line PDP-11/60 for analysis of taped data. Each system has 124K words of memory and runs under DEC's RSX-11D operating system. The on-line computers are interfaced to several CAMAC crates through a Microprogrammable Branch Driver (MBD). Each system is also equipped with two Tektronix 4010 terminals, a Versatec printer/plotter, at least one RK05 disk drive, a 9 track 75 IPS 800/1600 BPI Kennedy tape drive, and a 40MB Diva/Calcomp disk drive system which is compatible with DEC software for their RP03. The software developed for these systems was designed to meet the goals of flexibility and speed of analysis for multiparameter data (20-100 words/event). The LAMPF standard data aquisition package O and its associated routines for histogram management are used as the basis of the system. A number of additional features have been added whose usefulness appears to he common to most experiments of this type.

Application of an Array Processor to Data Analysis in Medium Energy Physics

The rate at which data may be acquired using LAMPF's high resolution magnetic spectrometers, HRS and EPICS, at times considerably exceeds the rate at which it may be analyzed with the on-line PDP-11/45's. At HRS in particular, data is routinely taken in a mode where less than 20% of the events may be completely analyzed even using well optimzed software. In order to achieve a situation in which data may be analyzed at a rate comparable to that at which it was acquired, a Floating Point Systems AP-120B Array Processor has been interfaced to the off-line PDP-11/60. The goal of this combination is to produce a system on which data may be analyzed at least a factor of 5 faster than is possible on-line, while maintaining as nearly as possible the same capabilities and user interface as with the standard off-line or on-line analysis.

On-Line Polynomial Optimization for High Resolution Spectromieters

A method has been developed to use a standard linear least squares routine to optimize various calculated quantities for the high resolution magnetic spectrometers of EPICS and HRS at LAMPF. Calculated quantities, such as x position at the target, can be expressed as polynomials of other calculated quantities and positions and angles directly determined by wire chambers. For each event (particle through the spectrometer) that satisfies predetermined limits, these coordinates (position, angle, momentum, etc.) are written to a disk file. A program which includes a linear least squares routine can then take an unlimited number of these events and do a fit to a polynomial consisting of terms which are up to fourth order in the coordinates of these events.

Nuclear reaction analysis of 16O concentration profiles with a high-resolution magnetic spectrometer

The (d, p) and (d, α) nuclear reactions have been used to measure 16O concentration profiles with a high-resolution magnetic spectrometer as an analyzer. Experimental data illustrating advantages, limitations, and general features of this analysis technique are presented.

Study of the 6Li(p, π +) 7 Li reaction at 600 MeV

The positive pion prodution through the 6Li(p, π +) reaction at 600 MeV has been studied using the high-resolution magnetic spectrometer SPES I. Differential cross sections have been measured from 5° to 35° lab. The 6Li(p, π +) reaction feeds preferentially the 4.63 MeV 7 2 − level of 7Li. The results of a calculation based on two- and three-nucleon diagrams with π and ρ exchange between the projectile and a bound nucleon are also presented.

KL0pcharge-exchange scattering from 550 to 1000 Mev/c

Employing a neutral kaon beam at the Argonne Zero Gradient Synchrotron, a high-resolution magnetic spectrometer, and a neutron detector, differential cross sections have been obtained in the forward direction (0.045 .. K/sup +/n. Previous studies of the time-reversed process in deuterium, K/sup +/d ..-->.. K/sup 0/p (p), have not yielded direct cross-section measurements in the forward direction because there is an inhibition of the non-spin-flip process in deuterium due to the Pauli exclusion principle. Nevertheless, our data are in agreement with the extracted free-neutron cross sections of deuterium studies as determined from the impulse and closure approximations. (AIP)