Radioactive Beams Research Articles

A novel smart rad-hard fast detection system for Radioactive Ion Beam Tagging and Diagnostics

Radioactive Ion Beams (RIBs) of large intensity (106pps or higher) are at the frontier in nuclear physics. We designed a novel detection system for RIBs diagnostics and tagging based on Silicon Carbide detectors and on custom frontend electronics ready to be coupled with a Real Data Management Unit. The full detection system is designed to measure the spatial distribution of the beam intensity and trajectory with sufficient spatial resolution (of the order of 1-2 mm). In addition, the detection system has to determine the RIB composition that can be obtained from the joint measurement of the energy loss (>E) of the ions passing through the sensors and the time of flight between two sensors or with respect to a given reference signal as the RadioFrequency signal of a Cyclotron. In this paper we present the full design of the proposed system together with the results of the first experimental qualification of the first mini-prototype. The paper also shows the steps towards the final detection system, housed in a DN160 spherical cross and able to cover an active area of 30 mm × 60 mm.

Development of high performance PIN-silicon detector and its application in radioactive beam physical experiment

In view of the great demand for large-area silicon detectors in domestic nuclear physics experiments, a type of 300-μm-thick high-performance square silicon detector with a large active area of 50 mm×50 mm by using overprinting technology is developed in the Institute of Modern Physics of the Chinese Academy of Sciences. Based on this technology, SiO<sub>2</sub> contamination caused by the photolithography and corrosion processes is effectively reduced. The detector has an excellent performance with a yield of up to 80%. Under –45 V (depletion voltage) bias, the leakage current of the detector is less than 40 nA. The detector is tested with a three-component α radioactive source. The energy resolution (<i>σ</i>) is about 45 keV for 5-MeV α particles. Used as an energy deposition(Δ<i>E</i>) detector, the detector performance is also tested for measuring reaction products of 250 MeV/u <sup>11</sup>C radioactive beams impinging on a carbon target. The results show that the charge number resolution of a single silicon detector is 0.17 for the carbon isotope, which is similar to that measured with the same type of detectors available from the market. With the average deposition energy of three silicon detectors used, the charge number resolution for carbon isotope reaches a better value of 0.11. With this resolution, C and B isotopes are clearly distinguished, meeting the requirements for particle identification in intermediate- and high-energy radioactive beam experiments.

A technique for studying (n,p) reactions of astrophysical interest using radioactive beams with SECAR

The formation of nuclei in slightly proton-rich regions of the neutrino-driven wind of core-collapse supernovae could be attributed to the neutrino-p process (νp-process). As it proceeds via a sequence of (p,γ) and (n,p) reactions, it may produce elements in the range of Ni and Sn, considering adequate conditions. Recent studies identify a number of decisive (n,p) reactions that control the efficiency of the νp-process. The study of one such (n,p) reaction via the measurement of the reverse (p,n) in inverse kinematics was performed with SECAR at NSCL/FRIB. Proton-induced reaction measurements, especially at the mass region of interest, are notably difficult since the recoils have nearly identical masses as the unreacted projectiles. Such measurements are feasible with the adequate separation level achieved with SECAR, and the in-coincidence neutron detection. Adjustments of the SECAR system for the first (p,n) reaction measurement included the development of new ion beam optics, and the installation of the neutron detection system. The aforementioned developments along with a discussion on the preliminary results of the p(58Fe,n)58Co reaction measurement are presented.

Radioactive Ion Beams: Production and Experiments at INFN-LNL

In this contribution the main mechanisms and techniques for the production of Radioactive Ion Beams are reviewed. In particular, the in-flight facility EXOTIC at INFN-LNL will be described and the results of a recent measurement of interest for the cosmological 7Li problem will be presented.

Ni target development for the TULIP project

The TULIP project (https://anr.fr/Projet-ANR-18-CE31-0023) aims to produce radioactive ion beams of short-lived neutron-deficient isotopes using fusion-evaporation nuclear reactions in an Isotope Separator On Line (ISOL) system. A Ni target was chosen to produce Rb and Sn isotopes, and was bombarded, respectively, by Ne and Cr primary beams at energies close to the Coulomb barrier. Owing to the Target Ion Source System (TISS) configuration, the operational TISS temperature had to be close to 1300°C. Several tests were performed to determine a configuration able to cope with the constraints related to the TISS, target and beam. This article presents a brief description of the TULIP principles and objectives, and the development of the Ni target.

Study of (p,2p) fission reactions in inverse kinematics using the R3B set-up

A new experimental fission approach is presented in the context of the R3B (Reactions with Relativistic Radioactive Beams) collaboration, at the GSI/FAIR facility, in which knockout reactions in inverse kinematics are used to induce fission of 238U that will allow to characterise the excitation energy of the fission process and all the fission products. The CALIFA (CALorimeter for In-Flight detection of γ-rays and high energy charged pArticles) calorimeter, a key part of the R3B set-up, is used to reconstruct the momenta of the two protons from the (p, 2p) reactions. Preliminary results show that kinematic variables and first estimates for nucleon-removal cross sections are well reconstructed and in good agreement with other experimental measurements.

Constraining nucleosythesis in neutrino-driven winds using the impact of (α, xn) reaction rates

The lighter heavy elements of the first r-process peak, between strontium and silver, can be synthesized in the moderately neutron-rich neutrino–driven ejecta of either core–collapse supernovae or neutron star mergers via the weak r–process. This nucleosynthesis scenario exhibits uncertainties from the absence of experimental data from (α, xn) reactions on neutron–rich nuclei, which are currently based on statistical model estimates. We have performed a new impact study to identify the most important (α, xn) reactions that can affect the production of the lighter heavy elements under different astrophysical conditions using new, constrained (α, xn) reaction rates based on the Atomki-V2 αOMP. Our results show how when reducing the nuclear physics uncertainties, we can use abundance ratios to constrain the astrophysical conditions/environment. This can be achieved in the near future, when the key (α, xn) reaction rates will be measured experimentally in radioactive beam facilities.

Fission-fragment yields measured in Coulomb-induced fission of 234,235,236,238U and 237,238Np with the R3B/SOFIA setup

Low energy fission of 234,235,236,238U and 237,238Np radioactive beams, provided by the GSI/FRS facility, has been studied using the R3B/SOFIA setup. The latter allows, on an event-by-event basis, to simultaneously identify, in terms of their mass and atomic numbers, the fissioning nucleus in coincidence with both fission fragments after prompt-neutron emission. This presentation reports on new results on elemental, isobaric and isotopic yields.

Total Absorption Spectroscopy of Fission Fragments Relevant for Reactor Physics and Nuclear Structure and Astrophysics

The accurate determination of reactor antineutrino spectra remains a very hot research topic, where new questions have emerged in recent years. Indeed, after the “reactor anomaly” – a deficit of measured antineutrinos at short baseline reactor experiments with respect to spectral predictions – the three international reactor neutrino experiments Double Chooz, Daya Bay and Reno have evidenced spectral distortions in their measurements with respect to the same spectral predictions. This puzzle is called the “shape anomaly”. Recently summation calculations of reactor antineutrino spectra based on the use of nuclear data have obtained the best agreement to date with the reactor neutrino flux measurements at the level of 2% thanks to a decade of Total Absorption Gamma-ray Spectroscopy (TAGS) measurements at the radioactive beam facility of the University of Jyväskylä in two experimental campaigns. A selection of the results obtained so far is presented.

Potential benefits of using radioactive ion beams for range margin reduction in carbon ion therapy

Sharp dose gradients and high biological effectiveness make ions such as 12C an ideal tool to treat deep-seated tumors, however, at the same time, sensitive to errors in the range prediction. Tumor safety margins mitigate these uncertainties, but during the irradiation they lead to unavoidable damage to the surrounding healthy tissue. To fully exploit the Bragg peak benefits, a large effort is put into establishing precise range verification methods. Despite positron emission tomography being widely in use for this purpose in 12C therapy, the low count rates, biological washout, and broad activity distribution still limit its precision. Instead, radioactive beams used directly for treatment would yield an improved signal and a closer match with the dose fall-off, potentially enabling precise in vivo beam range monitoring. We have performed a treatment planning study to estimate the possible impact of the reduced range uncertainties, enabled by radioactive 11C ions treatments, on sparing critical organs in tumor proximity. Compared to 12C treatments, (i) annihilation maps for 11C ions can reflect sub- millimeter shifts in dose distributions in the patient, (ii) outcomes of treatment planning with 11C significantly improve and (iii) less severe toxicities for serial and parallel critical organs can be expected.

Probing the quadrupole transition strength of C15 via deuteron inelastic scattering

Deuteron elastic scattering from $^{15}\mathrm{C}$ and inelastic scattering reactions to the first excited state of $^{15}\mathrm{C}$ were studied using a radioactive beam of $^{15}\mathrm{C}$ in inverse kinematics. The scattered deuterons were measured using HELIOS. The elastic scattering differential cross sections were analyzed using the optical model. A matter deformation length ${\ensuremath{\delta}}_{d}=1.04(11)\phantom{\rule{0.16em}{0ex}}\mathrm{fm}$ has been extracted from the differential cross sections of inelastic scattering to the first excited state. The ratio of neutron and proton matrix elements ${M}_{n}/{M}_{p}=3.6(4)$ has been determined from this quadrupole transition. Neutron effective charges and core-polarization parameters of $^{15}\mathrm{C}$ were determined and discussed. Results from ab initio no-core configuration interaction calculations were also compared with the experimental observations. This result supports a moderate core decoupling effect of the valence neutron in $^{15}\mathrm{C}$ similarly to its isotone $^{17}\mathrm{O}$, in line with the interpretation of other neutron-rich carbon isotopes.

Facility upgrade for superheavy-element research at RIKEN

The RIKEN Nishina Center (RNC) executed an accelerator upgrade project for the heavy-ion linac (called RILAC). A superconducting RIKEN linear accelerator (SRILAC) and a new superconducting electron-cyclotron-resonance ion source (SC-ECRIS) to boost the final energy and intensity were constructed, aimed at synthesizing a new superheavy element, 119, through a hot fusion reaction. The project included the construction of a gas-filled recoil ion separator (GARIS-III) suitable for detecting the residues of the hot-fusion reaction. To avoid research interruption during the SRILAC construction period (2017–2019) and gain experience in hot-fusion reaction processes, GARIS-II located in the GARIS experimental hall in LINAC building was moved to the E6 experimental hall in Nishina building. Certain exploratory measurements were performed employing the beams accelerated by RILAC2 and the RIKEN ring cyclotron (RRC), which is a part of the existing accelerator complex of the radioactive isotope beam factory (RIBF). Further, commissioning experiments with the upgraded facility (SRILAC and GARIS-III) were performed. The upgrade project and its commissioning results are chronologically described in this article.

Radioactive ion beam opportunities at the new FRAISE facility of INFN-LNS

At the Laboratori Nazionali del Sud of INFN (INFN-LNS) in Catania, the construction of the new Radioactive Ion Beams (RIBs) facility FRAISE (FRAgment In-flight SEparator) has reached its ending phase. The facility uses the in-flight technique based on a primary beam fragmentation impinging on light Be or C targets. FRAISE makes use of light and medium mass primary beams, having power up to ≈ 2–3 kW, leading to RIBs, whose intensities vary in the range of ≈ 103–107 pps, for nuclei far from and close to the stability valley, respectively. FRAISE aims at providing high-intensity and high-quality RIBs for nuclear physics experiments, also serving to interdisciplinary research areas, such as medical physics. Critical aspects for high-quality beams are the tuning and transport, representing time-consuming processes and requiring dedicated diagnostics and tagging devices measuring many features of RIBs. Some of these devices should be capable to operate in radioactively activated environments because of the expected 2 kW beam lost in the dipole after the production target. Due to its peculiar robustness to radioactive damage, Silicon Carbide (SiC) technology has been considered for the detection layer. In this view, an R&D campaign has been started aiming at developing the FRAISE facility, the new diagnostics system, and a new tagging device, the latter of which will be useful for the CHIMERA multidetector beamline. In this paper, we discuss the status and the perspectives of the facility with a focus on the RIBs opportunities.

Laser photo-ionization study of nat Ag using opto-galvanic signal at SPES offline laser lab

Resonant Ionization Laser Ion Source (RILIS) is one of the most advancing techniques for the production of radioactive ion beams (RIBs) in ISOL facilities. SPES project at INFN-LNL is a second generation ISOL facility which aims to produce several isotopes in a couple of years. Within the framework of this project, resonant photo-ionization schemes of several elements are studied in the offline laser lab, to be later implemented in the SPES Laser Ion Source. Silver is one of the elements being studied for the stated purpose. In this article, we report a resonant photo-ionization scheme of silver tested with a hollow cathode lamp (HCL). Evidence of high lying Rydberg states around 60945.32 cm−1 has also been observed by studying the fast opto-galvanic signal detected.

An FPGA-based trigger system for CSHINE

A trigger system of the general function was designed using the commercial module of CAEN V2495 for heavy-ion nuclear reaction experiments at Fermi energies. The system was applied and verified on the compact spectrometer for heavy IoN experiment (CSHINE). Based on the field-programmable logic gate array technology of the command register access and remote computer control operation, trigger functions can be flexibly configured according to experimental physical goals. Using the trigger system on CSHINE, we conducted a beam experiment at 25 MeV/u $$^{86}\textrm{Kr}+ ^{124}\textrm{Sn}$$ on the Radioactive Ion Beam Line 1 in Lanzhou, China. The online results demonstrated that the trigger system worked normally and correctly. This system can be extended to other experiments as well.

Thermal and Structural Characterization of a Titanium Carbide/Carbon Composite for Nuclear Applications

In the framework of ISOL (isotope separation on-line) facilities, porous carbides are among the most employed target materials for the production of radioactive ion beams for research. As foreseen by the ISOL technique, a production target is impinged by an energetic particle beam, inducing nuclear reactions from such an interaction. The resulting radionuclides are subsequently released, thanks to the high target working temperature (1600-2000 °C); ionized; and extracted into a beam. Since the target microstructure and porosity play a fundamental role in the radionuclide release efficiency, custom-made target materials are often specifically produced, resulting in unknown thermal and structural properties. Considering that such targets might undergo intense thermal stresses during operation, a thermal and structural characterization is necessary to avoid target failure under irradiation. In the presented work, a custom-made porous titanium carbide that was specifically designed for application as an ISOL target was produced and characterized. The thermal characterization was focused on the evaluation of the material emissivity and thermal conductivity in the 600-1400 °C temperature range. For the estimation of a reference material tensile stress limit, the virtual thermoelastic parameter approach was adopted. In particular, for the aforementioned temperature range, an emissivity between 0.7 and 0.8 was measured, whereas a thermal conductivity between 8 and 10 W/mK was estimated.

Effects of different types of radiation therapy on cardiac-specific death in patients with thyroid malignancy.

Radiation therapy (RT) is one of the common and widely used treatment method for thyroid tumors. Considering that the thyroid is located close to the heart, the radiation generated during the treatment of thyroid tumors may have an adverse greater impact on the heart. This study is to explore the influencing factors, especially additional effects of RT, on cardiac-specific death among patients with malignant thyroid tumors. Collecting information from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database using SEER*Stat. Patients with malignant thyroid tumors were searched, whether receiving RT or not. Ultimately, 201, 346 eligible patients were included. Propensity Score Matching (PSM) was used to minimize bias of baseline characteristics by adjusting for confounding factors. COX (proportional hazards) and fine-gray (competing risk) model regression analysis were used to explore the effects of various influencing factors on cardiac-specific death. The present analysis showed that, compared with non-RT, RT based upon radioactive implants and beam radiation were associated with lower risk of cardiac-specific death in patients with thyroid malignancy, beam radiation therapy may had a similar effect. Besides, the remaining RT methods did not significantly increase the risk of cardiac-specific death. In addition, Asian or Pacific Islander ethnicity, female sex, marital status, combined summary stage (localized, regional, and distant), high-income, and later year of diagnosis were associated with lower risk of cardiac-specific death. While older age of diagnosis, African ethnicity, non-Hispanic ancestry, and derived AJCC stage (IV) were risk factors for cardiac-specific death. These results help to identify the factors influencing cardiac-specific death among patients with thyroid malignancies. Furthermore, it may helps to improve the clinical application of RT without too much concern about adverse cardiac effects.

The General Purpose Ion Buncher: A radiofrequency quadrupole cooler-buncher for DESIR at SPIRAL2

We report on the conception and first tests of the General Purpose Ion Buncher (GPIB), the radio-frequency beam-cooler and buncher that will supply the DESIR (Decay, Excitation and Storage of Radioactive Ions) experimental hall to be constructed to complement the SPIRAL1 and SPIRAL2 facilities in GANIL. Its goals are both to reduce the emittance and if necessary to bunch the radioactive ion beam from the GANIL production facilities to adapt it to the needs of the different experimental setups in the DESIR hall. The mechanical design is similar to the existing ISCOOL quadrupole at ISOLDE but the new radio-frequency system enables a much stronger radial confinement. The GPIB is developed at LP2i Bordeaux11LP2i Bordeaux was known as Centre d’Études Nucléaires de Bordeaux-Gradignan (CENBG) before the name was changed in 2022. in parallel with the PIPERADE double Penning trap and a beamline has been constructed there to characterize both. The cooling of a 30keV beam to an emittance of 3 π mm mrad and a transmission above 80% in continuous mode is demonstrated for currents up to a few nA. Some first results concerning the bunching mode are also shown though this mode is still under development.

High-precision measurement of the He6 half-life

The half-life of $^{6}\mathrm{He}$ has been measured using a low-energy radioactive beam implanted in an ${\mathrm{YAlO}}_{3}$ Ce-doped inorganic scintillator and recording decay events in a $4\ensuremath{\pi}$ geometry. Events were time-stamped with a digital data acquisition system enabling a reliable control of dead-time effects and detector gain variations. The result, ${T}_{1/2}=(807.25\ifmmode\pm\else\textpm\fi{}0.{16}_{\mathrm{stat}}\ifmmode\pm\else\textpm\fi{}0.{11}_{\mathrm{sys}}$) ms, provides the most precise value obtained so far and is consistent with the only previous measurement having a precision smaller than 0.1%. This resolves the long-standing discrepancy previously observed between two sets of measurements.

β decay of neutron-rich Cu76 and the structure of Zn76

The $\ensuremath{\beta}$ decay of $^{76}\mathrm{Cu}$ to the levels of $^{76}\mathrm{Zn}$ was studied at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Lab (ORNL). A purified $^{76}\mathrm{Cu}$ beam was developed and data were recorded for the decay of the $A=76$ decay chain using four high-purity germanium (HPGe) clover detectors at the Low-energy Radioactive Ion Beam Spectroscopy Station (LeRIBSS). In this measurement, data on \ensuremath{\gamma}-ray emission following $\ensuremath{\beta}$ decay, including $\ensuremath{\beta}\ensuremath{\gamma}$ and $\ensuremath{\gamma}\ensuremath{\gamma}$ coincidences, were collected and $\ensuremath{\gamma}\ensuremath{\gamma}$ spectra were analyzed to identify the statistically significant coincidences. From this analysis, we propose a level scheme for $^{76}\mathrm{Zn}$ which contains a total of 59 energy levels up to 6.0 MeV containing 105 $\ensuremath{\gamma}$ rays. We have identified an additional 53 $\ensuremath{\gamma}$ rays associated with this decay which could not be place in the decay scheme due to insufficient coincidence information or no energy match to identified levels. No $\ensuremath{\gamma}$ rays from states in $^{75}\mathrm{Zn}$ fed in the delayed-neutron branch were observed even though other $\ensuremath{\gamma}$ rays in the $A=75$ decay chain were observed. Spin and parity assignments are proposed for some levels based on comparison to systematics and shell model calculations.