ΔE Detector Research Articles

E-ΔE detection module of DGFRS-2 setup

Thе paper describes a new E-ΔE detection module which includes a position-sensitive double-sided strip detector (DSSD) and a low-pressure pentane-filled ΔE chamber for detection of Evaporation Residues (ERs) in complete fusion reactions. The goal is to synthesize superheavy isotopes at the new DC-280 (Dubna Cyclotron) cyclotron of the Joint Institute for Nuclear Research (JINR). With the 48Ca ion beam intensity of about 5–7 pμA (particle micro ampere) and the ΔE counter count rate of approximately 104 sec−1, we observe a decrease in the overall registration efficiency of the gas ΔE counter. The paper proposes a solution to this problem: introduction of an additional negatively biased electrode, which results in the stabilization of the ΔE detector operation.

Studying the Yields of Reactions 13C(γ, p), 14N(γ, 2p), and 14N(γ, 2n) on a Pulsed Electron Accelerator with of (12B, 12N) Activity Measured by ΔE Detector Telescopes

Studying the Yields of Reactions 13C(γ, p), 14N(γ, 2p), and 14N(γ, 2n) on a Pulsed Electron Accelerator with of (12B, 12N) Activity Measured by ΔE Detector Telescopes

Об изучении выходов реакций 13C(𝛾, p) 12B, 14N(𝛾, 2p) 12B, 14N(𝛾, 2n) 12N при измерениях (12B, 12N)–активности телескопами Δ𝐸–детекторов между импульсами ускорителя электронов

The possibilities are analyzed for studying the yields of reactions 13C(𝛾, 𝑝) 12B, 14N(𝛾, 2𝑝) 12B, 14N(𝛾, 2𝑛) 12N by measuring the induced (12B, 12N)-activity with telescopes of thin Δ𝐸–detector in time intervals between electron accelerator pulses. For production of (12B, 12N)- nuclei and registration of their decay, estimates are given taking into account the parameters of the electron beam, Ta–radiator and irradiated targets made from graphite or NH4NO3, as well as the parameters of scintillation Δ𝐸 detector telescopes made from thin plastic plates.

Development of a gaseous Xe scintillator for particle identification of high-intensity and heavy ion beams

We have developed a gaseous Xe scintillator as a new ΔE detector which is expected to have good radiation hardness and fast response. In this research, we made a new version of the detector whose thickness is comparable to that of an ion chamber which is the current standard ΔE detector in RIBF. We carried out a performance test of the detector in RIBF. The root-mean-square (rms) resolutions of the atomic number Z around Z=35 and Z=55 are found to be about 0.2 and 0.3, respectively. In addition, it has a good timing resolution for a 238U beam of 74.4(6)ps in rms.

ΔE–E Telescope for the Detection of Charged Particles Based on a Si Detector and a SiPM Array with Scintillation Crystals

The characteristics of a ΔE–E telescope, which is planned to be used in the experimental setup focused on few-nucleon reactions, are studied. The required parameters of the ΔE–E telescope were determined on the basis of the numerical modeling of probable reactions. The telescope comprises a ΔE detector, which is a totally depleted surface-barrier silicon detector with a diameter of 8 mm and a thickness of ~24 μm, and an E detector based on LFS-8 crystals and a 16-element SiPM ARRAYC-30035-16P-PCB array. The telescope is designed, in particular, for coincidence detection of two charged particles emitted at close angles. This is made possible by the matrix structure of the E detector. The time resolution of the ΔE detector and the time and amplitude resolutions of all cells of the E detector were determined. The standard method of detection of two γ quanta from the beta decay of 22Na was used to measure the time resolution. Time coincidences of signals from the ΔE detector and a neutron detector based on a liquid scintillator (EJ-301) with its FWHM no worse than 1 ns were obtained. Similar measurements for the E-detector cells revealed time (less than 0.6 ns) and amplitude (~15% at an energy of ~1 MeV) resolutions that satisfy the experimental requirements for particle sorting and determination of their energy. The intrinsic background of the E detector, which arises from the radioactivity of LFS-8 crystals, was measured. The relative number of events corresponding to simultaneous triggering of two or more E-detector cells irradiated with α particles from a 226Ra source was also determined. This value may help estimate the number of random coincidences in a real experiment.

HYTAR: A HYbrid Telescope ARray detection system for heavy ion nuclear reactions around Coulomb barrier

Characteristics and performance of a HYbrid Telescope ARray (HYTAR) detector system for heavy ions are presented. The system has been developed for the study of reaction mechanisms in nuclear physics experiments around the Coulomb barrier. HYTAR apparatus is an array of hybrid telescopes, each unit comprising of a gas ionization chamber followed by a silicon detector. Gas ionization chamber, operated in axial field mode, measures the differential energy loss (ΔE), while the residual energies are measured by silicon detector. Particle identification is realized by implementing ΔE-E technique. Use of gas ionization chamber as ΔE detector allows identification of reaction channels down to low energy thresholds ∼ 0.1 MeV/A in A∼ 100 region. The detector system has been developed to investigate the fusion and fusion–fission dynamics by performing quasi-elastic scattering and fission angular distribution experiments. Processing of the detector signals is realized with compact and simple high density front-end electronics, which consists of custom developed low noise charge sensitive preamplifiers (operated inside vacuum) and differential driver NIM modules, followed by commercially available spectroscopy amplifiers, logic modules, analog to digital converters etc. Design features of the HYTAR and measurements performed with it are described in this article.

Total reaction cross sections measurement for 6,8He and 8,9Li nuclei with energies of (25–45)/A MeV on natAl and natPb

Preliminary results of measurements of the total reaction cross sections σR for weakly-bound 6,8He and 8,9Li nuclei at energy range (25–45)/A MeV on 27Al and 208Pb targets are presented. The secondary beams of 6,8He and 8,9Li were produced by bombardment of the 11B (33 A MeV) primary beam on Be (89 mg cm–2) target and separated by COMBAS fragment-separator. In dispersive focal plane a horizontal slit defined the momentum acceptance as 1% and a wedge degrader of 200 μm Al was installed. The Bρ of the second section of the fragment-separator was adjusted for measurements in energy range (25–45)/A MeV. The secondary products were detected by a telescope consisting of two Si ΔE detectors 300, 1000 μm and E-detector, which consisted of nine CsI/Tl granules.

Fabrication of a thin silicon detector with excellent thickness uniformity

We have fabricated and tested a thin silicon detector with the specific goal of having a very good thickness uniformity. SOI technology was used in the detector fabrication. The detector was designed to be used as a ΔE detector in a silicon telescope for measuring solar energetic particles in space. The detector thickness was specified to be 20μm with an rms thickness uniformity of±0.5%. The active area consists of three separate elements, a round centre area and two surrounding annular segments. A new method was developed for measuring the thickness uniformity based on a modified Fizeau interferometer. The thickness uniformity specification was well met with the measured rms thickness variation of 43nm. The detector was electrically characterized by measuring the I–V and C–V curves and the performance was verified using a 241Am alpha source.

Background reduction in 236U/238U measurements

The measurements of actinide isotopic ratios, in particular 236U/238U, in environmental samples requires high sensitivity. In particular, special effort must be devoted to the suppression of interfering nuclides, such as 235,238U, when measuring 236U. At the AMS facility of CIRCE, isotopic ratios down to ∼10−10 are currently measured using a gas E−ΔE detector. In order to push this limit lower towards natural levels, a time-of-flight system is used, featuring a micro-channel plate start detector and a Si stop detector. As the mass resolution of the latter is limited by the layout, an attempt to reduce the abundant isotope interference by other means has been undertaken.In this study, we report preliminary results on the characterization of the presence of molecular interferences when using UO−, UC− and UC2− as injected molecular ions. In particular the possibility to stabilize the current yield from carbide cathodes has been investigated: it was found that the best cathode preparation procedure is obtained pressing U salts baked at 800°C mixed with graphite and Al powder. Moreover, the 238U background in 236U measurements is strongly reduced injecting UC− ions, as verified using a time-of-flight detection system. On the other hand, 235U interference is larger with respect to UO− injection, but this increase is smaller than expected on the basis of abundances of 13C and 17O in UC and UC2 molecules on one side and UO, on the other.

Low-temperature technique of thin silicon ion implanted epitaxial detectors

A new technique of large-area thin ion implanted silicon detectors has been developed within the R&D performed by the FAZIA Collaboration. The essence of the technique is the application of a low-temperature baking process instead of high-temperature annealing. This thermal treatment is performed after B+ ion implantation and Al evaporation of detector contacts, made by using a single adjusted Al mask. Extremely thin silicon pads can be therefore obtained. The thickness distribution along the X and Y directions was measured for a prototype chip by the energy loss of α-particles from 241Am (〈E α 〉 = 5.5 MeV). Preliminary tests on the first thin detector (area ≈ 20 × 20 mm2) were performed at the INFN-LNS cyclotron in Catania (Italy) using products emitted in the heavy-ion reaction 84Kr (E = 35 A MeV) + 112Sn. The ΔE − E ion identification plot was obtained using a telescope consisting of our thin ΔE detector (21 μm thick) followed by a typical FAZIA 510 μm E detector of the same active area. The charge distribution of measured ions is presented together with a quantitative evaluation of the quality of the Z resolution. The threshold is lower than 2 A MeV depending on the ion charge.

Efficient ultra-thin transmission silicon detectors for a single-ion irradiation system at the Lund Ion Beam Analysis Facility

This paper describes the fabrication of efficient ultra-thin silicon transmission detectors for use as pre-cell detectors in single-ion experiments on living cells at the Lund Ion Beam Analysis Facility. More than 40 detectors of different thicknesses down to 5 μm have been fabricated and packaged. The main design considerations were very low leakage current (below 9 nA) and low full depletion voltage at biases less than 0.5 V at room temperature. In addition, we have shown that cooling the device can reduce the leakage current to 3 nA. The experimental testing of the pre-cell detection system is based on counting the passage of ions through the transmission (ΔE) detector before hitting the stopping (E) detector placed behind it, to ensure the accurate delivery of specific doses of radiation to the sample. Optimal detection of the fabricated detectors for the passage of an external beam of 2.2 MeV protons was obtained by cooling the device to below 2°C. Cooling the ΔE detectors provides up to 20% better energy resolution and up to 98% detection efficiency for 2.2 MeV protons. The development of this kind of efficient pre-cell detector enables a range of new experiments to be conducted on thick biological samples.

Response of a silicon telescope microdosimeter to 400 AMeV carbon ions

A monolithic silicon telescope consisting of a surface ΔE detector 2 μm in thickness coupled to an E detector about 500 μm in thickness made out of a single silicon wafer was recently proposed for the microdosimetric characterization of hadron beams. This device and its pixelated version are intended to be irradiated at the Centro Nazionale di Adroterapia Oncologica (CNAO, National Centre for Oncological Hadrontherapy, Pavia, Italy) with a 400 AMeV carbon ion beam. The response of the silicon microdosimeter under these conditions was calculated with Monte Carlo simulations by using the FLUKA code, in order to have reference available for comparison with the experimental results.

A monolithic silicon telescope for hadron beams: numerical and experimental study of the effect of ΔE detector geometry on microdosimetric distributions

A monolithic silicon telescope consisting of a surface ΔE detector 2 μm in thickness coupled to an E detector about 500 μm in thickness made out of a single silicon wafer was recently proposed for the microdosimetric characterization of hadron beams. This work discusses the study of the effect of the geometrical structure of the ΔE detector on microdosimetric distributions measured by the silicon device in hadron beams. Two different devices, i.e. a single-diode ΔE detector 1 mm in sensitive area and a ΔE detector geometrically segmented in micrometric cylinders, were irradiated at different phantom depths with 62 AMeV carbon ions in the same experimental conditions. In order to reproduce and deeply analyze the experimental results, a detailed numerical study based on Monte Carlo simulations was carried out through the FLUKA code version 2012, a recent release able to transport heavy ions at energies lower than 100 AMeV (the older lower transport limit) by exploiting the new Boltzman Master Equation model. The comparison between microdosimetric distributions measured by the two different detectors highlighted discrepancies at low lineal energies. Those differences, not reproduced by simulations, are probably due to charge sharing between the ΔE electrodes and the surrounding guards of the segmented device.

Light ion production in 175 MeV quasi mono-energetic neutron induced reactions on carbon, oxygen, and silicon

Double-differential cross sections of light ions (p, d, t, 3 He, and α) from carbon, oxygen, and silicon induced by 175 MeV quasi mono-energetic neutrons were measured using the Medley setup at the The Svedberg Laboratory (TSL) in order to benchmark evaluated nuclear data and nuclear reaction models. The Medley is a conventional spectrometer system which consists of eight counter telescopes. Each telescope is composed of two silicon surface barrier detectors as the ΔE detectors and a CsI(Tl) scintillator as the E detector for particle identification. The telescopes are placed at angles from 20° to 160° in steps of 20°. The measured double-differential production cross sections of light ions for oxygen and silicon are compared with PHITS calculations using the following nuclear reaction options: the high-energy nuclear data library (JENDL/HE-2007), the quantum molecular dynamics (QMD) model, the modified quantum molecular dynamics (MQMD) model, and the intra-nuclear cascade (INC) model based on the Bertini Model.

Characterizations of new ΔE detectors for single-ion hit facility

This paper describes the performance evaluation of new ΔE detectors to be used as pre-cell hit detectors in living cell irradiation experiments at the Lund Ion Beam Analysis facility (LIBAF). Using these detectors with a thickness down to 4.15μm fabricated at Lund University, an experiment was setup in which ΔE-detectors were used together with a stop E-detector in a telescope system under coincidence measurements. The characteristics of ΔE detectors were based on the optimal detection of the passage of 2.55MeV protons. The results of these tests demonstrate that the detector telescope clearly separates the protons, this due to high signal-to-noise ratio and good energy resolution of the ΔE-detectors. The best performing detector was shown to have a detection efficiency of 95% at thickness of 9.7μm. This type of high-performing detector is suitable for the planned role of the ΔE-detector in the future cell irradiation experiments.

Development of integrated ΔE–E silicon detector telescope using silicon planar technology

Abstract An integrated ΔE–E silicon detector telescope using silicon planar technology has been developed. The technology developed is based on standard integrated circuit technology and involves double sided wafer processing. The ΔE and E detectors have been realized in a PIN configuration with a common buried N+ layer. Detectors with ΔE thicknesses of 10, 15 and 25 μm, and E detector with thickness of 300 μm have been fabricated and tested with alpha particles using 238Pu–239Pu dual alpha source. The performance of the detector with ΔE detector of thickness 10 μm and E detector of thickness 300 μm has been studied for identification of charged particles using 12 MeV 7Li+ ion beam on carbon target. The results of these tests demonstrate that the integrated detector telescope clearly separates the charged particles, such as alpha particles, protons and 7Li. Due to good energy resolution of the E detector, discrete alpha groups corresponding to well known states of 15N populated during the reaction could be clearly identified.

The SiRi particle-telescope system

A silicon particle-telescope system for light-ion nuclear reactions is described. In particular, the system is optimized for level density and γ‐ray strength function measurements with the so-called Oslo method. Eight trapezoidal modules are mounted at 5cm distance from the target, covering eight forward angles between θ=40∘ and 54°. The thin front ΔE detectors (130μm) are segmented into eight pads, determining the reaction angle θ for the outgoing charged ejectile. Guard rings on the thick back E detectors (1550μm) guarantee low leakage current at high depletion voltage.

Aging of ErT2 thin films: ERD analysis and mechanical property changes

Abstract Rare earth tritide films evolve as tritium decays into 3He, which forms bubbles that influence long-term film stability in applications such as neutron generators. We followed the properties of model ErT2 films as they aged using ERD analysis to monitor T and 3He profiles, nanoindentation testing for mechanical properties and transmission electron microscopy to characterize bubble growth. The profiles of T and 3He are separately measured in ERD using a ΔE − E detector, taking advantage of the differences in energy loss within the ΔE detector. The composition measured by ERD followed the expected build-up of 3He up to near critical release, where 3He begins to escape from the film as bubbles overlap. These measurements complement observations of the changing mechanical properties of these films, where the observed behavior divided into two regimes: a substantial increase in layer hardness but elasticity little changed over ∼18 months, followed by a decrease in elastic stiffness and a modest decrease in hardness over the final 24 months. The evolution of properties has been explained by a combination of dislocation pinning by the bubbles, elastic softening as the bubbles occupy an increasing fraction of the material, and details of bubble growth modes. The ERD measurements confirm that the changes in properties are due to changes in bubble morphology and not to changes in 3He or T content.

Application of pulse shape discrimination in Si detector for fission fragment angular distribution measurements

Pulse shape discrimination (PSD) with totally depleted transmission type Si surface barrier detector in reverse mount has been investigated to identify fission fragments in the presence of elastic background in heavy ion-induced fission reactions by both numerical simulation and experimental studies. The PSD method is compared with the other conventional methods adopted to identify fission fragments with solid-state detectors such as ΔE–E telescope and single thin ΔE detector and the data for the10B +232Th fission reaction are presented. Results demonstrate the usefulness of a single transmission-type surface barrier detector for the identification of fission fragments and projectiles like heavy ions

Elastic recoil detection analysis on the ANSTO heavy ion microprobe

The heavy ion microprobe at the Australian Nuclear Science and Technology Organisation is capable of focussing heavy ions with an ME/ q 2 of up to 100 amu MeV. This makes the microprobe ideally suited for heavy ion elastic recoil detection analysis (ERDA). However, beam currents on a microprobe are usually very small, which requires a detection system with a large solid angle. We apply microbeam heavy ion ERDA using a large solid angle ΔE− E telescope with a gas ΔE detector to layered structures. We demonstrate the capability to measure oxygen and carbon with a lateral resolution of 20 μm, together with determination of the depth of the contamination in thin deposited layers.