Bragg Curve Spectroscopy Research Articles

Bragg curve spectroscopy for improved fission fragment identification

We report on the development of Bragg curve spectroscopy techniques to improve fission fragment identification in the measurement of independent fission product yields. The NIFFTE collaboration’s fissionTPC detector provides ionization energy and particle tracking information from neutroninduced fission targets. A joint effort between PNNL, LLNL, LANL, and the Colorado School of Mines is investigating the ionization profiles deposited by U-235, U-238, and Pu-239 fission products in this detector, with the goal of including additional stopping power information beyond a standard 2E analysis. The aim is to improve the determination of fragment atomic and mass numbers with this information, via methods such as parametric fits and machine learning techniques.

Low-energy-threshold detector for measuring proton spectra at several tens of MeV using Bragg curve spectroscopy

We have developed a low-energy-threshold detector comprising a Bragg curve counter (BCC), two silicon-surface barrier detectors, and a bismuth germanate scintillator to obtain experimental double-differential cross section (DDX) data on (p,p′x) reactions for incident energies of several tens of MeV. The BCC can identify particles by itself and can do so for protons down to 1 MeV. The developed detector is used to measure the DDXs of (p,p′x) reactions for incident proton energies of 40 and 70 MeV at 15–150°. The minimum energy in the DDX data is 1.3 MeV, which gives spectra of emitted particles in the whole energy range. The resultant DDXs are compared with results calculated using intranuclear cascade plus evaporation models. Below 10 MeV, the calculation results agree reasonably with measured data for the natC(p,p′x), 27Al (p,p′x), and natCu(p,p′x) reactions, but they disagree regarding energy and angular dependence for the 197Au(p,p′x) reaction.

A new analysis method using Bragg curve spectroscopy for a Multi-purpose Active-target Particle Telescope for radiation monitoring

Traditional radiation detectors can either measure the total radiation dose omnidirectionally (dosimeters), or determine the incoming particles characteristics within a narrow field of view (spectrometers). Instantaneous measurements of anisotropic fluxes thus require several detectors, resulting in bulky setups. The Multi-purpose Active-target Particle Telescope (MAPT), employing a new detection principle, is designed to measure particle fluxes omnidirectionally and be simultaneously a dosimeter and spectrometer. It consists of an active core of scintillating fibers whose light output is measured by silicon photomultipliers, and fits into a cube with an edge length of 10cm. It identifies particles using extended Bragg curve spectroscopy, with sensitivity to charged particles with kinetic energies above 25MeV. MAPT's unique layout results in a geometrical acceptance of approximately 800cm2sr and an angular resolution of less than 6°, which can be improved by track-fitting procedures. In a beam test of a simplified prototype, the energy resolution was found to be less than 1MeV for protons with energies between 30 and 70MeV. Possible applications of MAPT include the monitoring of radiation environments in spacecraft and beam monitoring in medical facilities.

Collinear ternary cluster decay of hyperdeformed 60Zn at high angular momentum

Binary and ternary cluster decay of 60Zn compound nuclei at high angular momentum, formed in the 36Ar + 24Mg reaction at E lab(36Ar) = 195 MeV, has been measured in a unique kinematic coincidence setup consisting of two large area position sensitive (x, y) gas detector telescopes with Bragg-ionization chambers (BRS). The BRS provides the opportunity to measure the reaction angles in-and out-of-plane, and through Bragg-curve spectroscopy to achieve a complete identification of the nuclear charge for different final channels. We observed very narrow out-of-plane angular correlations for two heavy fragments emitted either in purely binary events or in events with a missing mass consisting of 2 and 3α particles. These narrow correlations are interpreted as ternary fission decay from compound nuclei at high angular momenta through an elongated (hyperdeformed) shape with a very large moment of inertia. In these stretched configurations, the lighter mass in the neck region remains at rest or with very low momentum in the center of mass.

Light charged particle and intermediate mass fragment cross-sections in GeV proton-induced reactions

As an international collaboration PISA (Proton Induced SpAllation) has initiated measurements of total and double differential cross-sections for products of spallation reactions at the proton accelerator COSY in Jülich (Germany) in order to study secondary particle production created in structural, window, and target materials by proton beams up to 2.5 GeV incident kinetic energy. In the framework of Spallation Neutron Sources and accelerator-driven systems, residual nuclei (H, He up to intermediate mass fragrments) production cross-sections are of great importance for estimation of damage in target and structural materials. Reliable and comprehensive experimental data, especially for p-energies beyond 1 GeV will serve as benchmarks for code development and validation. Data taken by Bragg curve spectroscopy and silicon detector telescopes for the reaction 1.9 GeV p+Ni(Au) will be discussed and kinetic energy spectra of light ions and intermediate mass fragments will be presented.

Measurement of differential cross sections for evaluation of radiation dose of ten’s of MeV neutrons

Double differential cross sections of several ten’s of MeV neutron induced reactions for elements composing the human tissue were measured using specially designed spectrometers at TIARA 7Li(p,n) neutron source. In spectroscopy of particles from neutron induced reactions, a large solid angle and particle acceptance detector is indespensable. For particles from 5 MeV a to 70 MeV proton, a spectrometer consisting of three counter telescopes and a vacuum chamber was used. For heavier particles, a Bragg curve spectroscopy technique was adopted to neutron field. Double differential cross section of p,d,t,a emission for N and O were obtained using the former spectrometer. In the later method we fabricated a test spectrometer to check applicability and signal to noise ratio in neutron field. Using the spectrometer, energy spectra of heavier particles (Li, Be, B, C) from carbon were observed.

A Bragg curve spectroscopy detector for ERDA studies

The design and use of a Bragg curve spectroscopy (BCS) detector for depth profiling of elements in materials using the elastic recoil detection analysis (ERDA) technique is discussed. The detector when used to identify recoils from samples in an ERDA experiment using a 170 MeV Ag beam showed a clear separation between Fe ( Z = 26) and Cu ( Z = 29) recoils. Measurements near Z = 11 yielded ΔZ Z of 1 34 showing a Bragg peak resolution of 2.9%. For typical applications, the detector can be effectively used for neighbouring charge identification up to Z ∼ 30.

MAGIC — Multi Anode Gas Ionization Chamber

A novel approach to the Bragg curve spectroscopy is utilized to construct a charged particle detector which makes fragment elemental identification and energy measurement possible. The advantage of the construction includes good timing and spectroscopic properties with a very low energy threshold.

A method to study heavy ion reactions using position sensitive and Bragg curve spectroscopy detectors

A large area Bragg curve spectroscopy (BCS) detector and a position sensitive parallel grid avalanche counter have been developed to study heavy ion reactions, such as inelastic excitations and few nucleon transfer reactions near the Coulomb barrier. Reasonably good resolutions have been achieved for energy, atomic number and angle. A theoretical investigation on the mass dependence of the Bragg peak signal from the BCS detector, shows that there is a negligible mass dependence related to the geometry of the detector. The mass number of the heavy ions which cannot be obtained by the above method, has been identified by detecting the corresponding characteristic gamma rays from the product nuclei with two large solid angle gamma ray detectors.

Depth profiles of C, N and O on carbon coated steel surfaces made by IBAD

The nitrogen ion implantation into steel surfaces by using an oil diffusion vacuum pumping system is superimposed with an ion beam assisted deposition process of a very thin carbon layer. The application of Bragg-curve spectroscopy to elastic recoil detection analysis (ERDA) of ion beam assisted deposited carbon layers on steel surfaces is described. The ERDA is used for simultaneous depth profiling of the light elements carbon, nitrogen and oxygen. Typical results are good selectivity of the atomic charge number Z up to 20 with a depth resolution on the order of 5 to 10 nm and submonolayer sensitivity. The low background in the operative region allows the analysis of profiles down to concentrations of about 0.01% of the stoichiometric ones. The ERDA depth profiling results are shown in correlation to measurements with Auger electron spectroscopy (AES).

Depth profiles of carbon, nitrogen and oxygen on carbon coated steel surfaces made by ion beam assisted deposition

The application of Bragg-curve spectroscopy to elastic recoil detection analysis (ERDA) of carbon layers deposited onto steel surfaces by ion beam assisted deposition is described. ERDA is used for simultaneous depth profiling of the light elements carbon, nitrogen and oxygen. Typical results are good selectivity of the atomic charge number Z up to 20 with a depth resolution on the order of 5–10 nm and submonolayer sensitivity. The low background in the operative region allows the analysis of profiles down to concentrations of about 0.01% of the stoichiometric concentrations. The depth profiling results of differently produced carbon layers are shown in correlation with the measured wear resistance and the technological parameters of the ion beam assisted deposition process.

Bragg curve spectroscopy in a 4π geometry

Ionization counters employing Bragg curve spectroscopy have been constructed for use in a 4π geometry. These detectors compare very favorably in terms of both energy and charge resolution with small solid angle devices. These detectors have a large dynamic range because they are backed by scintillation detectors, and are thus capable of detecting and identifying particles with energies from 1 MeV/nucleon up to 200 MeV/nucleon.

A broad-range detector system with large geometric efficiency for heavy-ion reaction studies

A detector module sensitive to heavy ions, capable of covering a very large solid angle, and having a broad dynamic range in energy and atomic number has been designed and tested. It is tapered, has a pentagonal cross section and has been constructed to permit close-packing in a spherical array with a minimum of inactive area. The detector consists of a radial-field drift chamber for Bragg-curve spectroscopy, followed by a thin fast-plastic scintillator laminated to a thick slow-plastic scintillator for light-ion detection; the two scintillators are read together in phoswich ΔE — E mode. Mixed-mode operation is also possible, with the drift chamber serving as a ΔE counter and the fast plastic scintillator providing an energy signal. Tests with a beam of 145 MeV 28Si ions have shown that for 83% geometric efficiency (active/total solid angle) the Bragg curve spectrometer gives ΔZZ ⋍ 5% at Z = 12 and ΔEE ⋍ 6% for silicon ions depositing 100 MeV in the detector. Mixed mode operation has 70% geometric efficiency with a measured ΔZZ ⋍ 5% for Z = 8. Phoswich mode operation also has 70% geometric efficiency and gives ΔZZ ⋍ 6% for Z = 2; isotopic identification of light ions is unambiguous.

Performance of a bragg ionization chamber for depth profiling and surface analysis

The application of Bragg-curve spectroscopy to ERD and RBS is described. In particular, the performance for depth profiling and surface analysis is investigated. Advantages and limitations are discussed. Typical results are good selectivity of the atomic charge number Z up to 20 with a depth resolution on the order of 10 nm and submonolayer sensitivity. An important advantage is the possibility of combining in one measurement the spectroscopy of recoil ions and scattered projectiles. The method is limited by the condition that the energy of the detected particles should be within the operative region of a nearly constant Bragg-peak height. An estimate of this low-energy limit is derived. The low background in the operative region allows the analysis of profiles down to concentrations of about 0.01% of the stoichiometric ones. For different ions the energy calibrations were found to differ by about 3%. The basic ideas and preliminary results of a quantitative analysis of depth profiles are described.

Bragg curve spectroscopy of fission fragments by using parallel plate avalanche counters

By using a charge-sensitive preamplifier and methods of energy spectroscopy we investigated the response of a parallel plate avalanche counter in order to scan the Bragg curve. The detector was operated in butabe, pentane and heptane which also served as stopping gases. In this paper, we report on results obtained with fission fragments from a 252Cf source. We achieved a separation of the light and heavy fragment groups in the interval of gas absorber thickness from about 500 μg cm −2 to 1.5 mg cm −2. The best energy loss resolution was achieved with pentane at E p ≃ 70 V cm −1 Torr −1 resulting in σΔE ΔE ≃ 13% . The corresponding shape of the ΔE spectrum reproduces correctly the nuclear charge distribution of the fragments.

Position sensitive and Bragg curve spectroscopy detector system

A heavy ion gas detector system consisting of a Bragg-curve spectroscopy ionization chamber for particle identification and a multiwire proportional chamber as position sensitive fast trigger device is described. The Bragg IC has been tested with several beams up to Z = 36 to investigate some aspects of the BCS method. Results are reported on energy resolution and linearity, Z resolving power and mass sensitivity. The energy resolution is well below 1%. The Bragg-peak amplitude is fairly independent of the energy in a wide energy range and single elements are identified up to Z = 38 with a resolving power Z/ ΔZ − 50-80. Isotope identification by range measurement is limited by the straggling in the ionization process and the mass resolving power is M/ ΔM ∼ 20–26 for S and Si isotopes. The MWPC allows subnanosecond time resolution and position identification along the in-plane coordinate within ±0.5 mm.

Nitrogen isotope identification by Bragg-curve spectroscopy

Projectilelike fragments following the 80 MeV16O +27A1 reaction have been detected using a Bragg-curve spectroscopy ionization chamber (BCS-IC). The atomic number is deduced from the Bragg-peak amplitude. Nitrogen isotopes are clearly resolved using either range or energy loss data. This is the first application of the BCS method for complete ion identification in a heavy-ion—induced reaction.

Developments of heavy-ion gas detectors at LNL

The most important developments in gaseous detectors at LNL are reviewed. Some aspects of timing, pulse height and position resolutions of avalanche counters are reported. The experimental work on heavy-ion identification by Bragg curve spectroscopy is summarized.

First experimental results at the XTU Tandem of the laboratori nazionali di Legnaro

The actual status of the XTU-16 MV Tandem Laboratory at Legnaro and the related scientific program are outlined. A review of some preliminary results obtained during the performance tests of the accelerator is presented. The data reported concern: i) The spectroscopy of neutron-deficient fusion-evaporation residues produced in inverse reactions like46,48Ti+27Al and32,34S+27Al at energies of 3.5 MeV/a.m.u. in the compound-system mass region of 60 ÷ 80 and by means of the energy time-of-flight telescope and in-beam γ-ray spectroscopy techniques. ii) The investigation of statistical effects in deep inelastic processes evidenced in the mass regionA≲150, not far above the Coulomb barrier; a typical example is the reaction32S+100Mo atE/B∼1.4 by inclusive measurements of the fragments with by Bragg-curve spectroscopy technique. iii) The evidence of intermediate mechanisms in processes involving composite-mass system aroundA=100 and at energies of (3÷5) MeV/a.m.u.; these results are particularly significant in the behaviour of the energy and angle dependence of the heavy-fragment distribution for the reaction32S+59Co.

Performance of a Bragg curve detector for heavy ion identification

By using Bragg curve spectroscopy, one can measure atomic number and energy of high energy heavy ions stopping in a gas-filled ionization chamber with longitudinal electric field. In this paper, we report on the results obtained with an isobutane filled detector. An energy resolution of 0.8% fwhm and a Z resolution of 2.7% fwhm were achieved for elastically scattered 300 MeV 40Ar ions. We study the Bragg peak amplitude dependence on the energy of the incoming ions, a dependence presumably due to the Frisch grid screening inefficiency. The corrected Bragg peak spectrum of inelastically scattered 300 MeV 40Ar ions exhibits a satisfactory Z separation around Z=18.