The current Electron Cyclotron Resonance Ion Sources (ECRISs), constructed with Nb-Ti wires and the conventional racetrack-and-solenoid structure, have achieved operating frequencies up to 28 GHz and utilized about 90% of the critical current of the Nb-Ti wire. A Mixed Axial and Radial field System Demonstrator (MARS-D) is being developed at Lawrence Berkeley National Laboratory (LBNL). This system, which consists of an innovative hexagonal Closed-Loop Coil (CLC) and a set of solenoids, can generate higher magnetic fields (up to 150%) while requiring only about 50% of the superconducting wire, enabling Nb-Ti wires to be used in the next-generation 45 GHz ECRIS. However, the assembly and cooling of such an efficient and compact magnet are particularly challenging due to the small radial gap between the CLC and solenoids, as well as the tight operating temperature margin. To address these challenges, a structure was developed that combines a three-section radially split solenoid mandrel with a series of shrink-fit reinforcement rings and cooling channels. This paper presents the detailed structure, manufacturing method, assembly procedure, impregnation method, mechanical Finite Element Analysis (FEA) comparison, and thermal FEA comparison.

Electron Cyclotron Resonance Ion Sources (ECRISs) that utilize Nb-Ti superconducting coils for 28 GHz frequencies have been operating effectively for over twenty years. However, transitioning to higher frequencies demands stronger magnetic fields, and the conventional racetrack-and-solenoid ECRIS structures have reached their maximum capability with Nb-Ti. To address this, a Mixed Axial and Radial field System Demonstrator (MARS-D) is being developed at Lawrence Berkeley National Laboratory (LBNL). This system features an innovative Closed-Loop Coil (CLC) design that optimizes the use of the conductor fields, enabling the application of Nb-Ti in the next-generation 45 GHz ECRISs. The fabrication of the hexagonal CLC is particularly challenging due to its complex winding path and shape, the stiffness of the Nb-Ti superconducting wire, and the small bending radius. To address these challenges, a series of unique fixtures and tools, as well as a pre-over-bending method, were developed for winding the CLC. To validate the winding fixtures, tools, procedures, and materials used in the coil assembly, a 4-layer practice CLC was wound, epoxy-impregnated, and then cold-tested using liquid nitrogen. The full-size MARS-D CLC is in the process of winding. This paper presents the structure of the MARS-D CLC, the winding fixtures and tools, the winding procedures, the quality control, the impregnation, the test results, and the potential future improvements.

The proposed search for element 120 at LBNL’s 88-Inch Cyclotron will require the continual delivery of over a particle microamp of 50Ti12+ for weeks-long campaigns spanning many months. The VENUS electron cyclotron resonance ion source is the primary injector source for the 88-Inch Cyclotron, and the oven presented here can survive the source’s high magnetic fields while injecting metallic gas into the plasma with high efficiency. The oven design is vertical to permit use with metals that melt before outgassing sufficiently, while also allowing a rotation of the oven’s material exit toward the plasma center for better conversion efficiency to the produced beam. The overall oven design is presented, along with performance results from both the source and the accelerated beams through the cyclotron.

The ^{244}Pu(^{50}Ti,xn)^{294-x}Lv reaction was investigated at Lawrence Berkeley National Laboratory's 88-Inch Cyclotron. The experiment was aimed at the production of a superheavy element with Z≥114 by irradiating an actinide target with a beam heavier than ^{48}Ca. Produced Lv ions were separated from the unwanted beam and nuclear reaction products using the Berkeley Gas-filled Separator and implanted into a newly commissioned focal-plane detector system. Two decay chains were observed and assigned to the decay of ^{290}Lv. The production cross section was measured to be σ_{prod}=0.44(_{-0.28}^{+0.58})  pb at a center-of-target center-of-mass energy of 220(3) MeV. This represents the first published measurement of the production of a superheavy element near the "island of stability," with a beam of ^{50}Ti and is an essential precursor in the pursuit of searching for new elements beyond Z=118.

A custom waveguide dc break, developed for the versatile ECR for nuclear science (VENUS) ion source at Lawrence Berkeley National Laboratory, features an innovative impedance matching network. This network consists of two inductive irises located adjacent to a capacitive gap, which not only provides dc isolation but also facilitates the coupling of a new 2.4 kW Klystron, effectively doubling the power available for plasma production at the secondary frequency of 18 GHz. The design allows the ion source to operate at elevated potentials while keeping the RF system grounded, thereby ensuring efficient ion beam extraction and transportation to the cyclotron for acceleration, and maintaining easy access to the RF system. Simulations conducted with the ANSYS High-Frequency Structure Simulator, a finite element analysis tool, have demonstrated exceptional impedance matching at the Klystron frequency. These results have been corroborated by microwave measurements, showing excellent agreement.

The first deflector circuitry at the extraction of the 88-in Cyclotron at the Lawrence Berkeley National Laboratory has been modified to enable switching within a few hundreds of nanoseconds. This modification, along with the pre-chopper, allows the cyclotron to achieve single-bunch extraction. The novel procedure involves adjusting the pre-chopper to control the number of ion bunches injected into the cyclotron, thus managing ion energy deposition. These bunches are then accelerated until they reach the electrostatic deflectors, which control their extraction. After the deflectors are adjusted to transport the beam, the first deflector voltage is decreased until no beam current is extracted. Finally, through switching and selective phase adjustment of the first deflector to match the transit time of a bunch, the cyclotron is capable of extracting a single bunch. This capability is crucial for time-sensitive experiments and allows control over dose distribution in previously inaccessible regimes. The straightforward and cost-efficient implementation of this technique makes it an attractive option for many cyclotron facilities and medical cyclotron manufacturers.

A single radio frequency bucket of the 88-Inch Cyclotron is filled using a fast chopper located in the axial line. The bucket then accelerates until it reaches the deflector, at which point, it is extracted as a train of bunches. This phenomenon can be attributed to the characteristic multi-turn extraction of the cyclotron and, by simplifying the complex dynamics of a cyclotron, corresponds to the conceptual transfer function of the cyclotron. The confirmation of the single radio frequency bucket injection was achieved by operating the cyclotron in the third harmonic mode and observing the absence of intermediate bunches during the multiple-bunch extraction.

Superconducting electron cyclotron resonance ion sources (ECRISs) using NbTi coils and optimized for 28 GHz resonant heating have been successfully operated for almost two decades. Moving to higher heating frequencies requires increased magnetic fields, but traditional racetrack-and-solenoid ECRIS structures are at their limit using NbTi. Rather than moving to a superconductor untested in this field, the Mixed Axial and Radial field System (MARS) being developed at Lawrence Berkeley National Laboratory employs a novel closed-loop-coil design that more efficiently utilizes conductor fields and will allow the use of NbTi in a next-generation, 45 GHz ECRIS. This article presents the design of the shell-based support structure central to the MARS-D magnet design, as well as structural analysis of its components and optimization of pre-load parameters that will guarantee its successful operation.

The 88-lnch Cyclotron at Lawrence Berkeley National Laboratory has two LC tank circuits, called bunchers, that operate at the fundamental and second harmonic frequencies to longitudinally compress the beam entering the cyclotron, providing a beam current gain of 6. An automatic control system is designed and tested to facilitate the buncher tuning and allow consistent operation at maximum radio frequency output. The feedback system uses an Arduino microcontroller board that senses the tank circuit peak voltage and adjusts a variable capacitor to find and maintain the circuit at resonance. The system successfully passed performance tests, which simulate tuning conditions, with an initialization time of 30 seconds.

In outer space down to the altitudes routinely flown by larger aircrafts, radiation can pose serious issues for microelectronics circuits. The 88-Inch Cyclotron at Lawrence Berkeley National Laboratory is a sector-focused cyclotron and home of the Berkeley Accelerator Space Effects Facility, where the effects of energetic particles on sensitive microelectronics are studied with the goal of designing electronic systems for the space community. This paper describes the flexibility of the facility and its capabilities for testing the bombardment of electronics by heavy ions, light ions, and neutrons. Experimental capabilities for the generation of neutron beams from deuteron breakups and radiation testing of carbon nanotube field effect transistor will be discussed.

An experiment was performed at Lawrence Berkeley National Laboratory's 88-in. Cyclotron to determine the mass number of a superheavy element. The measurement resulted in the observation of two alpha-decay chains, produced via the Am-243(Ca-48,xn)(291-x)Mc reaction, that were separated by mass-to-charge ratio (A/q) and identified by the combined BGS + FIONA apparatus. One event occurred at A/q = 284 and was assigned to (284)Nh (Z = 113), the alpha-decay daughter of (288)Mc (Z = 115), while the second occurred at A/q = 288 and was assigned to (288)Mc. This experiment represents the first direct measurements of the mass numbers of superheavy elements, confirming previous (indirect) mass-number assignments.

An investigation is made into the stability of the fluence measurement accuracy over an extended time period. Beam profile fitting is performed to illuminate the underlying causes of changes in the fluence measurement accuracy.

The spectral temperature T-s obtained from bremsstrahlung spectra emitted from electron cyclotron resonance (ECR) ion sources (ECRISs), in which the plasma is confined in a minimum-B magnetic field, is used as a relative indication of the temperature of the plasma hot electrons. Past bremsstrahlung measurements taken on ECRISs indicate that Ts is strongly dependent on the magnetic field gradient at the resonance zone or (B-min/B-ECR). However, this dependence was never fully proven or explained. To further our understanding a more detailed study of the bremsstrahlung radiation for X-rays above 10 keV is underway using VENUS, a third-generation ECRIS at Lawrence Berkeley National Laboratory. Initial analysis of previous and new data has revealed that Ts appears to be dependent solely on the minimum magnetic field B-min rather than (B-min/B-ECR) and the microwave frequency omega. Decoupling T-s from (B-min/B-ECR), mainly B-ECR, implies that T-s does not depend on the magnitude of the heating frequency omega. While it certainly appears to be true that plasma density n(e)(alpha omega(2) alpha B-2) increases with heating frequency, as was postulated by Geller in 1987, a more careful consideration into the heating mechanism of the plasma electrons is warranted. The disassociation of T-s from the heating frequency omega, while an interesting discovery, implies that we must change the way we understand how ECRISs operate. This paper presents new bremsstrahlung measurements, analyses, and discussions of the results.

The nuclear reactions $^{12}\mathrm{C}(^{12}\mathrm{C},\ensuremath{\alpha})^{20}\mathrm{Ne}$, $^{12}\mathrm{C}(^{12}\mathrm{C},p)^{23}\mathrm{Na}$, and $^{12}\mathrm{C}(^{12}\mathrm{C},n)^{23}\mathrm{Mg}$ are the primary reactions in carbon burning, which occurs as part of several stellar processes. The Gamow window, which describes the energy range where most of these reactions take place, is typically around 1.5 MeV in the center-of-mass frame. Direct measurements of the cross sections at this energy are difficult due to the large Coulomb barrier present between the carbon nuclei; however, a successful surrogate measurement can provide the branching ratios between these reactions while avoiding the $^{12}\mathrm{C}+\phantom{\rule{0.16em}{0ex}}^{12}\mathrm{C}$ Coulomb barrier. An experiment was performed using inelastic scattering of 40 MeV $\ensuremath{\alpha}$ particles on $^{24}\mathrm{Mg}$ as a possible surrogate for the $^{12}\mathrm{C}+\phantom{\rule{0.16em}{0ex}}^{12}\mathrm{C}$ compound nucleus.

Electron Cyclotron Resonance (ECR) Ion Sources at Lawrence Berkeley National Laboratory's (LBNL) 88-Inch Cyclotron produce heavy ion cocktails to test the radiation hardness of spacecraft electronics. A 20 MeV/u cocktail is underway and the 10 MeV/u cocktail has been expanded to include gold.

An investigation is made of the trade-off between fluence measurement accuracy and ion changeover time. Allowing users to select fluence measurement accuracy based on the type of testing being performed and time available.

Axial bremsstrahlung from the superconducting Electron Cyclotron Resonance ion source VENUS have been systematically measured as a function of RF heating frequency, and the axial and radial field strengths. The work focuses on bremsstrahlung with energies greater than 10 keV to extract the spectral temperature Ts. The three axial coils and the radial coils in the superconducting VENUS can all be set independently and have a large dynamic range, which makes it possible to decouple Bmin and and study their effects on the bremsstrahlung independently. With typical pressure and RF power levels, the measurements show that Ts depends approximately linearly on Bmin and is not correlated with the , the magnetic field mirror ratios, or the RF frequency. These results are important for the next generation of ECR ion sources, which are designed to operate at frequencies above 40 GHz and significantly higher magnetic fields where bremsstrahlung is expected to cause a significant cryogenic heat load and increase the radiation shielding requirements.

. A segmented Si-telescope and HPGe array, STARS-LIBERACE, was used to study the 156 Gd(p , t γ ) 154 Gd direct reaction by particle- γ coincidence spectroscopy. New cross sections with a 25 MeV proton beam are reported and compared to previous (p, t) and (t, p) studies. Furthermore, additional evidence for coexisting K π = 0 +1 , 2 +1 and 0 +2 , 2 +2 configurations at N = 90 is presented. Direct and indirect population patterns of the low-lying states are also explored. Review of the new and existing evidence favors an interpretation based on a configuration-dependent pairing interaction. The weakening of monopole pairing strength and an increase in quadrupole pairing strength could bring 2p-2h 0 + states below 2 Δ . This may account for a large number of the low-lying 0 + states observed in two-nucleon transfer reactions. A hypothesis for the origin of the 0 +2 and 0 +3 states is provided.

We have determined the critical properties of infinite uncharged nuclear matter based on cluster emission data. To do this, three obstacles had to be overcome: finite size effects, the Coulomb interaction and appropriate physical picture (not particles coexisting in a box). That lead to the complete liquid to vapor phase diagram of neutral, symmetric, uncharged nuclear matter.

In the outer space down to the altitudes routinely flown by the larger commercial aircrafts, radiation is a serious problem for the microelectronics circuits. The 88-Inch Cyclotron at Lawrence Berkeley National Laboratory is a sector-focused cyclotron and is the home of the Berkeley Accelerator Space Effects Facility, where the effects of energetic particles on sensitive microelectronics are studied with the goal of designing electronic systems for the space community. The paper will describe the flexibility of the facility and its capabilities for testing the bombardment of the electronics by heavy ions, light ions, and neutrons.