U-400M Cyclotron Research Articles

Results of Reconstruction of U400M Cyclotron Magnetic Structure

U400M isochronous cyclotron was create on the base of U300 classic cyclotron and is under operation at FLNR, JINR since 1996. U400M cyclotron is intended for accelerating the ion beams with A/Z= 2.286 – 9 to energy W = 80 – 6 MeV/nucl. Cyclotron have H-type main magnet with 4-meter pole diameter and 4 pairs of spiral type sectors. In 2022 year, the reconstruction of cyclotron magnetic structure was held on. The reconstruction included the replacement of magnet main coil, mapping and correction of cyclotron magnetic field. In the frame of the mapping, the magnetic field was corrected to improve its average radial distribution and to compensate the first harmonic. For cyclotron magnetic field mapping the automatic measurement system, based on 14 Hall probes, was used.

Enhanced beam extraction system at the U-120M cyclotron

Since its commissioning in 1977, the U-120M cyclotron was initially equipped with a single pair of harmonic coils aimed at optimizing beam quality at lower accelerating radii. In 2022, a significant upgrade introduced a second pair of harmonic coils, positioned at a radius of approximately 50 cm, aligning with the outermost beam orbit. This addition is essential for the efficient extraction of positively accelerated ions and serves as the basis for the newly developed extraction system, which, unlike the original fully electrostatic system, consists of electrostatic deflectors and magnetic channels. This paper describes the design and installation of new harmonic coils in the accelerator vacuum chamber and presents a new extraction system using precession and linear integer resonance methods. Basic properties of these two extraction methods are given and finally, an evaluation of their advantages and limitations concerning their possible use in the cyclotron and an estimation of the efficiency of the new extraction system is made.

Silicon Carbide Timepix3 detector for quantum-imaging detection and spectral tracking of charged particles in wide range of energy and field-of-view

The hybrid architecture of the Timepix (TPX) family of detectors enables the use of different semiconductor sensors, most commonly silicon (Si), as well as high-density materials such as Cadmium Telluride (CdTe) or Gallium Arsenide (GaAs). For this purpose, we explore the potential of a silicon carbide (SiC) sensor bump-bonded on a Timepix3 detector as a radiation imaging and particle tracking detector. SiC stands as a radiation-hard material also with the ability to operate at elevated temperatures up to several hundreds of degrees Celsius. As a result, this sensor material is more suitable for radiation harsh environments compared to conventional e.g., Si sensors. In this work, we evaluate the response for precise radiation spectrometry and high-resolution particle tracking of newly developed SiC Timepix3 detector which is built and operated as a compact radiation camera MiniPIX-Timepix3 with integrated readout electronics. Calibration measurements were conducted with mono-energetic proton beams with energies of 13, 22, and 31 MeV at the U-120M cyclotron at the Nuclear Physics Institute Czech Academy of Science (NPI CAS), Prague, as well as 100 and 226 MeV at the Proton Therapy Center Czech (PTC) in Prague. High-resolution pattern recognition analysis and single-particle spectral tracking are used for detailed inspection and understanding of the sensor response. Results include distributions of deposited energy and linear energy transfer (LET) spectra. The spatial uniformity of the pixelated detector response is examined in terms of homogeneously distributed deposited energy.

Characterization of the secondary neutron field inside a cyclotron for production of radiopharmaceuticals

During production of radiopharmaceuticals, the radiation situation in cyclotron pit is an important parameter, which is being monitored to ensure fulfilment of the limits and conditions of safe operation. The neutron flux in the structural components of the accelerator is also an important parameter, because the secondary neutrons are responsible for activation of cyclotron structural components and may even affect structural changes in it. This paper aims to characterize the neutron field in inner positions of medical accelerator IBA 18/9 by activation detectors and by means of scintillation spectrometry. The backward angle measurement was realized also in special liquid water target (H218O) at U120M cyclotron to confirm the data obtained in IBA 18/9 cyclotron.

Measurements of the neutron spectra from the p+Be neutron generator of the NPI CAS

The Nuclear Physics Institute of the Czech Academy of Sciences (NPI CAS) operates several neutron sources, including a generator of a continuous spectrum of neutrons up to 33 MeV. Accelerated protons from the U-120M cyclotron are directed to an 8 mm thick beryllium target to produce the neutrons.In this work, the neutron spectrum at distances of 3–8 m was directly measured with NE213 and stilbene scintillator detectors in the forward, diagonal and perpendicular directions. At a distance of 50 cm from the Be target, the neutron spectrum was validated with a gold activation detector. From previous work, the neutron spectra at close distances were characterized for use in high-intensity irradiation. Both the newly measured spectra at large distances and the previously measured spectrum were simulated using the Monte Carlo code, MCNP6.2, with ENDF7PROT and JENDL-4.0/HE nuclear data libraries. The comparison of the simulated and experimentally measured spectra revealed several limitations of both libraries.

Charged particle induced reactions on beryllium as a fast neutron source for irradiation experiments

Nuclear Physics Institute of the Czech Academy of Sciences (NPI CAS) in Rez operates the compact accelerator-driven NG-2 fast neutron source. The NG-2 neutron source uses proton (up to 35 MeV) and deuteron (up to 20 MeV) beams extracted from the isochronous cyclotron U-120M and beryllium target station for broad neutron spectrum production and lithium target station for quasi-monoenergetic neutron field production (the p+Li(C) reaction on thin target). These sources are primarily focused on nuclear data measurement and validation, especially for the future fusion energetics (DEMO and IFMIF-DONES research programs). To extend their experimental utilization mostly towards some more traditional research reactor applications (such as the neutron activation analysis and material research), the neutron fields generated by the p+Be and d+Be source reactions for various energies of charged particle beams provided by the U-120M cyclotron have been recently studied using the multi-foil activation technique. New neutron fields based on the p(35 MeV)+Be, p(30 MeV)+Be, p(24 MeV)+Be, and p(20 MeV)+Be source reactions as well as the d(20 MeV)+Be, d(15 MeV)+Be, and d(10 MeV)+Be reactions are available at NPI CAS now.

Spectral tracking of proton beams by the Timepix3 detector with GaAs, CdTe and Si sensors

Position and directional-sensitive spectrometry of energetic charged particles can be performed with high resolution and wide dynamic range (energy, direction) with the hybrid semiconductor pixel detectors Timepix/Timepix3. The choice of semiconductor sensor material, thickness, and properties such as the reverse bias voltage, greatly determine detector sensitivity and resolving power for spectrometry and particle tracking. We investigated and evaluated the spectral tracking resolving power such as deposited energy and linear-energy-transfer (LET) spectra with the Timepix3 detector with different semiconductor sensors, based on GaAs:Cr, CdTe, and Si, using well-defined radiation sources in terms of radiation type (protons), energy, and incident direction to the detector sensor. Measurements of particle incident direction in a wide range were performed with collimated monoenergetic proton beams of various energies in the range 8–31 MeV at the U120-M cyclotron at the NPI CAS Rez near Prague. All detectors were per-pixel calibrated. This work enables to examine and perform a detailed study of charge sharing and charge collection efficiency in semiconductor sensors. The results serve to optimise the detector chip-sensor assembly configuration for measurements especially with high-LET particles in ion radiotherapy and outer space. The work underway includes evaluation of newly refined semi-insulating GaAs sensors and improved radiation hard semiconductor sensors SiC.

Validation of calculational determination of 18O(p,n) secondary neutron field

Cyclotrons used to produce medical isotopes are relatively widespread. Nowadays, it is popular to place small and compact accelerators directly in hospitals. This approach simplifies handling of the produced radiopharmaceuticals, but it imposes strict radiation safety measures during production. For optimal utilization of isotope production cyclotrons, the exact knowledge of leakage neutron field is essential due to the deep penetration ability of the high energy neutrons and the accompanied secondary radiation production. Our paper presents measurement of the neutron leakage spectra for various angles from an open target assembly at the cyclotron U-120M at NPI of CAS. These spectra are compared with data obtained from a compact medical cyclotron IBA Cyclone 18/9 in UJV Rez and also with activation measurements of reactions with different threshold energies. All data were also compared with calculations made with different Monte Carlo codes using both models and data libraries. The preliminary results show significant disagreement between experiments and theoretical predictions. These findings could have implications not only to the nuclear data community but also to the production accelerators operators at the licensing stage.

High Priority Request List cross-section measurements: 7Li(d,x)7Be/3H and 39K(n,p)39Ar

The Nuclear Energy Agency’s High Priority Nuclear Data Request List is a compilation of the highest priority nuclear data requirements. The U-120M cyclotron of the Nuclear Physics Institute of the Czech Academy of Sciences is a suitable tool for studies of several reactions from this list. In this paper, we present the measurements of the 7Be and 3H production in the lithium-7 after the irradiation with deuterons and the validation measurement for the 39Ar production in 39K after irradiation with neutrons .

Изучение механизмов реакций с тяжелыми ионами и получение вторичных радиоактивных пучков с помощью фрагмент-сепаратора КОМБАС.

Experiments in that Be and Ta targets have been bombarded by heavy ions in series 12C, 15N, 18O, 22Ne and 40Ar are discussed. Ions was accelerated at energy 35-45 MeV/nucleon on the U-400M cyclotron at Flerov Laboratory of Nuclear Reactions, JINK. The targets were placed at the entrance focus of the COMB AS separator. Reaction products near zero-angle degrees were collected and then analyzed. The telescope formed from silicon detectors was placed at the exit achromatic focus of separator. One from pair of parallel plate avalanche counters (PPAC) has been placed at the dispersive focal plane and the other before the silicon detectors. Reaction products was identified on the mass number A and atomic number Z by the (ДЕ. K) telescope and by the (AE. T) method using lime of flight between PPAC. The measurements of the yields of isotopes were carried out by scanning the range of magnetic rigidities covering the velocity distributions of the studied isotopes. The results of the experiments was analyzed and compared with different theoretical models. The generation of radioactive beam of 11Li with maximum intensity and its purity was the objective of this experiment. Achieved maximum intensity is 104 nuclei at second.

The activation cross section measurements of proton-induced reactions on Li and Ta in the energy region 12.5–34 MeV

The experimental data on cross sections are necessary to clarify existing ideas on the mechanisms of nuclear reactions and for testing of nuclear models. Proton-induced reaction on 7Li serves as a source of quasi-monoenergetic neutrons which are widely used in the measurement of cross sections for neutron induced reactions. Tantalum plays an important role in technology and nuclear facilities mainly for its low induced activity (screens, degraders). In order to investigate the important nuclides, we have carried out the irradiation experiments with the variable-energy cyclotron U-120M of the NPI CAS Řež. The cross section of the reaction 7Li(p,n)7Be(ground state+0.43 MeV) and the cross sections of the nuclides 180,178mTa, 178W and 175Hf from reactions on natural tantalum were investigated, of which 181Ta(p,n)180gTa for the first time. The stacked-foil technique was utilized. The comparison of new results with prior data and predictions of evaluations is discussed.

Reconstruction of U400M Cyclotron: Upgrade of U400M Cyclotron Magnetic Structure

Reconstruction of U400M Cyclotron: Upgrade of U400M Cyclotron Magnetic Structure

Радиоактивационный контроль плотности износостойких покрытий AlN и CrN на кремнии

In this work, the mass and linear thicknesses of AlN and CrN coatings deposited onto silicon substrates by magnetron sputtering were measured, respectively, by a combination of the methods of nondestructive radioactivation analysis on proton beams of the U-120M cyclotron and optical micro-interferometry. It is shown that, at linear thicknesses in the range of 2.2-5.7 μm, the coating density is close to the values for bulk materials AlN (3.26 g / cm3) and CrN (5.9 g / cm3), and the stoichiometry of nitrides is controlled by the parameters of magnetron deposition. The technique can also be used to determine the density of wear-resistant coatings from carbides and metal oxides.

Calculating the Linear Energy Transfer Distribution in Radiobiological Experiments on the U400M Cyclotron

Radiobiological experiments with the irradiation of various biological samples by nuclei from boron to neon with a primary energy of 30–50 MeV/nucleon are performed on the U400M cyclotron of the Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research. The linear energy transfer (LET) of the nuclei in samples is calculated using the code Lise++. For reducing the energy of nuclei and increasing their LET, aluminum filters with different thickness are placed before samples. The presence of filters and other absorbers before a sample results in the production of secondary charged particles whose LET may strongly differ from the LET of primary nuclei of the beam. This also affects the accuracy of calculating the absorbed dose. For this reason, detailed calculations of particle fields in samples are performed using the Monte Carlo code for radiation transport in matter PHITS 3.20 for several variants of sample irradiation with thick absorbers before samples. The calculated LET distributions are analyzed and compared with the calculations using the code Lise++.

Production and study of neutron rich heavy nuclei, GALS setup

A new setup for production and investigation of exotic heavy neutron rich nuclei located in the "north-east" region of nuclear map is under construction at Flerov Laboratory for Nuclear Reactions (FLNR) of JINR, Dubna. The setup will use the available U-400M cyclotron beams for low energy multi-nucleon transfer reactions. Products of 4.5 to 9 MeV per nucleon heavy-ion collisions, such as 136Xe beam on 208Pb target, will be captured in a gas cell, selectively laser-ionized, transported towards mass separator by electrostatic ion guide extraction system and then to detecting system.

Deuteron-induced reactions on manganese at low energies

The scarce data systematics and complexity of deuteron interactions demand the update of both the experimental database and theoretical frame of deuteron activation cross sections. Various reactions induced by neutrons and protons following the deuteron breakup (BU) should be also taken into account. On the other hand, deuteron reaction cross sections recommended recently for high-priority elements are still based on data fit without predictive power. Purpose: Accurate new measurements of low-energy deuteron-induced reaction cross sections for monoisotopic (55Mn) natural manganese target enhance the related database as well as the opportunity of an unitary and consistent account of the related reaction mechanisms. Method: Activation cross sections of 54,56Mn, and 51Cr nuclei by deuterons on $^{55}$Mn were measured at energies <20 MeV by the stacked-foil technique and high resolution gamma spectrometry at the U-120M cyclotron of CANAM, NPI CAS. Then all available data for deuterons on 55Mn up to 50 MeV are analyzed paying particular attention to BU and direct reaction (DR) mechanisms. Results: Newly measured activation cross sections strengthen the deuteron database at low energies, at once with a consistent account for the first time of all available data. Conclusions: Due account of deuteron-induced reactions on 55Mn, including particularly the new experimental data at low energies, is provided by a suitable BU and DR assessment.

New detection systems at U-120M cyclotron

Intensive neutron beams with energies up to 33 MeV are produced using cyclotron driven broad-spectrum and quasi-monoenergetic neutron generators at the NPI CAS. The neutron beams are well characterized with the TOF and PRT measurements. The segmented Fe-CH2 collimator is used to collimate the neutron beam and two detection systems are being developed for the studies of the reactions with neutrons. The first one is the detection system of the charged particles at different angles from the (neutron, charged particle) reactions in a vacuum chamber, the second is an array of four HPGe detectors for the detection of direct and delayed gamma photons produced in reactions of the studied material with neutrons. The advanced bunching system is also being developed at the U120M cyclotron. It will allow to direct a short (few ns long) pulse of accelerated particles to the neutron converter with the 1 µs delay between bunches. Together with 7 m long flight path this extension will open new possibilities in the cross section measurements.

The activation of natZr by quasi-monoenergetic neutrons below 34 MeV

Good knowledge of cross section neutron induced reactions on Zr becomes of importance due to the use of zirconium as structural material in reactors, its applicability in neutron dosimetry and the theoretical model testing. Thin Zr foils (0.05 mm thickness, 99.2% purity) were irradiated in the quasi-monoenergetic p-Li neutron fields, the proton beams from NPI CAS variable-energy cyclotron U120M at proton energies 20.33, 22.44, 24.69, 27.64, 29.85, 32.31 and 35.11 MeV. Li target with carbon stopper was used for the generation of neutron flux. The reaction 7Li (p,n) produces the high-energy quasi-monoenergetic neutrons with a tail to lower energies. The flux density and neutron spectra were evaluated by MCNPX code and validated with set of measurements including Time-Of-Flight and Proton recoil Telescope and additional activation monitors. The pneumatic tranfer system enables the investigation of short living isotopes. The foil activity determination was performed by the nuclear spectrometry method employing two calibrated HPGe detectors. The reaction rates for natZr(n,*)89m,89g,89Zr, 87m,87,88,89m,90m,91m,92,93,94,95Y and 87m,91,92Sr were obtained and cross sections were extracted. The preliminary results are discussed.

Total neutron cross-section extracted from transmission experiments with liquid oxygen using neutron energies from 18 to 27 MeV

Fast neutron generators driven by isochronous cyclotron U-120M developed at Nuclear Physics Institute were used for neutron cross-section measurements. The target station with 2 mm thin lithium was used to produce pulsed beams of fast quasi-monoenergetic neutrons in the 7Li(p,n) reaction. The Time-of-Flight technique was used to determine the exact neutron energy spectra. The transmission measurements on liquid oxygen were conducted for several neutron peak energies between 18 and 27 MeV and the cross-sections for reaction natO(n,tot) were derived.

Characterization of Highly Irradiated ALPIDE Silicon Sensors

The ALICE (A Large Ion Collider Experiment) experiment at CERN will upgrade its Inner Tracking System (ITS) detector. The new ITS will consist of seven coaxial cylindrical layers of ALPIDE silicon sensors which are based on Monolithic Active Pixel Sensor (MAPS) technology. We have studied the radiation hardness of ALPIDE sensors using a 30 MeV proton beam provided by the cyclotron U-120M of the Nuclear Physics Institute of the Czech Academy of Sciences in Řež. In this paper, these long-term measurements will be described. After being irradiated up to the total ionization dose 2.7 Mrad and non-ionizing energy loss 2.7 × 10 13 1 MeV n eq · cm - 2 , ALPIDE sensors fulfill ITS upgrade project technical design requirements in terms of detection efficiency and fake-hit rate.