Search results for "Time of flight"
showing 10 items of 114 documents
A time-of-flight correction procedure for fast-timing data of recoils with varying implantation positions at a spectrometer focal plane
2019
Abstract Fast-timing measurements at the focal plane of a separator can suffer from poor timing resolution. This is due to the variations in time-of-flight (ToF) for photons travelling to a given detector, which arise from the changes in the implantation positions of the recoil nuclei emitting the γ rays of interest. In order to minimise these effects on timing measurements, a procedure is presented that improves fast-timing data by performing ToF corrections on an event-by-event basis. This method was used to correct data collected with an array of eight LaBr 3 detectors, which detected γ rays from spatially distributed 138Gd recoil-implants at the focal plane of the Recoil-Ion-Transport-U…
Time-of-flight ERD with a 200mm2 Si3N4 window gas ionization chamber energy detector
2014
Abstract Low energy heavy ion elastic recoil detection work has been carried out in Jyvaskyla since 2009 using home made timing detectors, a silicon energy detector and a timestamping data acquisition setup forming a time-of-flight–energy telescope. In order to improve the mass resolution of the setup a new energy detector was designed to replace the silicon solid state detector, which suffered from radiation damage and had poor resolution for heavy recoils. In this paper the construction and operation of an isobutane filled gas ionization chamber with a 14 × 14 mm 2 100 nm thick silicon nitride window are described. In addition to greatly improved energy resolution for heavy ions, the dete…
Depth resolution optimization for low-energy ERDA
2007
Abstract With the implementation of low-energy time-of-flight Elastic Recoil Detection Analysis (ERDA), routine analysis of thin films with high depth resolution becomes possible. The optimization of the measurement conditions is a key issue for an accurate sample characterization and is normally a compromise among depth resolution, mass resolution and sensitivity, for a given sample. In this work, we focus on the depth resolution optimization, presenting an extensive study of two different materials, SiO 2 and TiN, representative of light and medium mass targets. The film thickness varies between 10 and 50 nm. The samples were measured with different beams ( 35 Cl, 63 Cu, 79 Br and 127 I),…
Time-of-flight telescope for heavy-ion RBS
2007
Abstract This paper describes a time-of-flight (TOF) spectrometer for Heavy-Ion Rutherford Backscattering Spectrometry (HI-RBS) recently installed at IMEC for thin film analysis. The TOF telescope allows the use of ion beams heavier than He, with advantages in terms of depth and mass resolution and sensitivity compared to conventional RBS based on planar Si detectors. The start timing-signal is produced by the secondary electrons emitted from a thin C foil when traversed by a backscattered ion; the electrons are deflected in an electrostatic mirror towards a Micro-channel plate (MCP) assembly which provides a fast timing response. The stop signal is obtained directly from a second MCP assem…
Time-of-flight photoelectron momentum microscopy with 80–500 MHz photon sources: electron-optical pulse picker or bandpass pre-filter
2021
Journal of synchrotron radiation 28(6), 1891 - 1908 (2021). doi:10.1107/S1600577521010511
Stopping power measurement of 48Ca in a broad energy range in solid absorbers
2006
Abstract Stopping power of 48 Ca ions in C, Ni and Au was measured using TOF-E method. The results cover energy range from 0.1 to 5.3 MeV/u (5–250 MeV). The reliability of our experimental method was verified and confirmed by TOF–TOF measurements. The results are compared with theoretical (PASS) and semi empirical (SRIM2003) predictions.
Experimental neutron capture data of 58Ni from the CERN n_TOF facility
2014
The $^{58}$Ni $(n,\gamma)$ cross section has been measured at the neutron time of flight facility n_TOF at CERN, in the energy range from 27 meV up to 400 keV. In total, 51 resonances have been analyzed up to 122 keV. Maxwellian averaged cross sections (MACS) have been calculated for stellar temperatures of kT$=$5-100 keV with uncertainties of less than 6%, showing fair agreement with recent experimental and evaluated data up to kT = 50 keV. The MACS extracted in the present work at 30 keV is 34.2$\pm$0.6$_\mathrm{stat}\pm$1.8$_\mathrm{sys}$ mb, in agreement with latest results and evaluations, but 12% lower relative to the recent KADoNIS compilation of astrophysical cross sections. When in…
A Method for Measurements of the Total 2H(γ,π−)PP Cross Sections at Threshold
1979
In recent years measurements of the total cross section for the reactions 2H(γ,π+ nn) and 2H(γ,π0)2H close to the production threshold were performed1. For the 2H(γ,π−)pp reaction data of similar good quality doesn’t exist. In this paper a method is prescribed and the feasibility for the reaction 2H(γ,π−)pp is demonstrated. Figure 1 shows the principle: The photon beam hits a liquid or high pressured gas target of 2H. π− are created on the deuteron and stopped in the same target cell. The major part of the tt are captured π− are captured by deuterons via the reaction 2H(π−,n)n. The energy is shared equally by the two neutrons (En= 68.2 MeV). One of these monochromatic neutrons is detected b…
A time-of-flight facility for the measurement of electron-induced neutron spectra
1974
Abstract A time-of-flight facility is constructed to investigate photoneutrons in the energy range 5 MeV ≤ En ≤ 200 MeV. Photoneutrons are detected simultaneously at four angles (40.2°, 90°, 113.5°, 142.2°). The overall time resolution varies from 0.282 ns/m to 0.358 ns/m, depending on the different flight paths (18.56 m to 11.40 m). As a first check the facility is used to measure the ratio of the number of virtual photons to real photons via the photodisintegration of 2H. The measured values agree with the calculated photon spectra.
A method for measuring total cross sections of (γ, π−) reactions at threshold
1981
Abstract A new method for detecting low energy negative pions has been investigated. The negative pions are identified via monoenergetic neutrons produced in the reaction π − + D → 2 n and detected by means of a time of flight spectrometer. The feasibility for measuring D ( γ , π − ) cross sections near threshold is demonstrated; an extension to heavier nuclei seems to be possible. Futher the method is well suited for applications together with tagged photon beams.