A nuclear reaction product mass spectrometer

doi:10.1016/0029-554X(81)90742-4

Nuclear Instruments and Methods

Volume 184, Issues 2–3, 1 June 1981, Pages 423-430

https://doi.org/10.1016/0029-554X(81)90742-4 Get rights and content

Abstract

The design of a mass spectrometer capable of determining directly the mass of nuclear reaction products, independent of the velocity with which they leave the target, is discussed. The spectrometer employs only electric and magnetic dipoles and magnetic quadrupoles to focus all particles of a given mass to the same point on the focal plane. The usable solid angle is a function of the mass resolution and can be as large as 5 msr. The magnification of the device is 3.3 which means that the angular convergence of particle paths at the focal plane is very small with the consequence that the focal plane may, without significant loss of resolution be regarded as straight and perpendicular to the particle path in all practical cases. The mass dispersion of the spectrometer is ∼13 mm/% and the resolving power (a function of solid angle) can be as large as m/Δm = 400.

References (10)

H.A. Enge
H. Wollnik
S. Kowalski, MIT Informal Report,...
H. Ewald
Nucl. Instr. and Meth.
(1976)

There are more references available in the full text version of this article.

Cited by (39)

Measurement of charge state distributions using a scintillation screen
2023, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Absolute cross sections measured using electromagnetic devices to separate and detect heavy recoiling ions need to be corrected for charge state fractions. Accurate prediction of charge state distributions using theoretical models is not always a possibility, especially in energy and mass regions where data is sparse. As such, it is often necessary to measure charge state fractions directly. In this paper we present a novel method of using a scintillation screen along with a CMOS camera to image the charge dispersed beam after a set of magnetic dipoles. A measurement of the charge state distribution for ⁸⁸Sr passing through a natural carbon foil is performed. Using a Bayesian model to extract statistically meaningful uncertainties from these images, we find agreement between the new method and a more traditional method using Faraday cups. Future work is need to better understand systematic uncertainties. Our technique offers a viable method to measure charge state distributions.
Initial operation of the recoil mass spectrometer EMMA at the ISAC-II facility of TRIUMF
2019, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
The Electromagnetic Mass Analyser (EMMA) is a new vacuum-mode recoil mass spectrometer currently undergoing the final stages of commissioning at the ISAC-II facility of TRIUMF. EMMA employs a symmetric configuration of electrostatic and magnetic deflectors to separate the products of nuclear reactions from the beam, focus them in both energy and angle, and disperse them in a focal plane according to their mass/charge $(m ∕ q)$ ratios. The spectrometer was designed to accommodate the $γ$ -ray detector array TIGRESS around the target position in order to provide spectroscopic information from electromagnetic transitions. EMMA is intended to be used in the measurement of fusion evaporation, radiative capture, and transfer reactions for the study of nuclear structure and astrophysics. Its complement of focal plane detectors facilitates the identification of recoiling nuclei and subsequent recoil decay spectroscopy. Here we describe the facility and report on commissioning efforts.
Increasing recoil mass spectrometers' resolution by using crossed-field analyzers
2009, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
The mass dispersion of the QQEBEQQ symmetric recoil mass spectrometers can be improved substantially, so potentially their resolution, by inserting cylindrical plates inside the magnet gap, thus creating there a crossed field analyzer. The conditions to keep stigmatic and energy focusing were derived for such a modified system. Applied to some specific cases these formulae predict an increase of even 200% in mass dispersion for an increase of total charged particle path by 7.92%. The mass separation of equal momentum beams at middle of the instrument and the resolution-beam acceptance product were calculated for two representative separator configurations.
A Monte Carlo code to calculate transmission efficiency of HIRA
2007, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
A semimicroscopic Monte Carlo code is presented for calculating absolute transmission efficiency of the Heavy Ion Reaction Analyzer at IUAC. The code generates realistic distributions for energy, charge state and angle of evaporation residues (ERs) produced in heavy ion-induced complete fusion reactions. Further, individual ER trajectories are calculated using first-order transfer matrices. Trajectories in dispersive and non-dispersive planes and one as well as two-dimensional position spectra of the ERs at the focal plane are simulated by the code. Calculated efficiencies are in good agreement with measurements.
EMMA: A recoil mass spectrometer for ISAC-II at TRIUMF
2005, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Design work has begun on EMMA, an electromagnetic mass analyzer for ISAC-II at TRIUMF. EMMA is a recoil mass spectrometer that will be used to separate the recoils of nuclear reactions from the beam, and to disperse them according to mass/charge. ISAC-II will provide intense, low-emittance beams of unstable nuclei with masses up to 150 u and maximum energies of at least 6.5 MeV/nucleon. EMMA will be used in many different types of experiments with radioactive beams, especially those involving fusion-evaporation and transfer reactions. As such, it must be both efficient and selective, possessing large acceptances in angle, mass, and energy without sacrificing the necessary beam suppression and mass resolution.
A modular focal plane detector system for the heavy ion reaction analyzer at NSC, New Delhi
1996, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
A detector system has been developed for the focal plane of the HIRA. It consists of two independent detectors, a low-pressure multiwire proportional counter (LP-MWPC) followed by a split-anode ionization detector. Details of the design and test results are presented. Using slow preamplifiers, the position resolution is ≥1 mm and the time resolution is estimated to be 1.5 ns for the LP-MWPC. The ionization detector gives 2.4% energy resolution for 150 MeV ²⁸Si scattered off a gold target and the ΔZ/Z obtained for ²⁸Si + ²⁷Al is $142$ for Z = 14. Some results for fusion and transfer studies for the ⁴⁸Ti + ⁵⁸Ni and ²⁸Si + ⁶⁸Zn systems, respectively, at energies around the Coulomb barrier, are presented to highlight the performance of the detector system.

View all citing articles on Scopus

^☆: Supported in part by the National Science Foundation.

View full text

A nuclear reaction product mass spectrometer☆

Abstract

Nucl. Instr. and Meth.