Range Of Heavy Ions Research Articles

Research on longitudinal dynamics and design of RF parameters of synchrotron for XiPAF-upgrading project

Xi ’an 200 MeV Proton Application Facility (XiPAF) will be upgraded to proton and heavy ion synchrotron recently. In order to ensure the enough life of heavy ion beam, the synchrotron requires ultra-high vacuum, and the designed static vacuum is better than 5×10-10 Pa. In order to place enough vacuum pumps in the synchrotron, the circumference of the synchrotron was increased from 30.9 m to 39.96 m. The revolution frequency range of heavy ions is 0.49∼1.03 MHz. In order to reduce the engineering difficulty and improve the lower limit of frequency bandwidth requirement of the RF system, the harmonic of h=2 is used to capture and accelerate the heavy ions, and the frequency bandwidth range of the RF system is adjusted from 1∼6 MHz to 0.8∼5.0 MHz. In this paper, the longitudinal dynamics parameters of the upgraded synchrotron are designed, and the simulation calculation is carried out. Finally, the parameter requirements of the RF system are proposed.

Production of neutron deficient rare earth radionuclides by heavy ion activation

Abstract The attempts to produce neutron deficient radioisotopes of rare Earth elements by heavy ion activation are discussed in this review. The heavy ion induced reaction products have large atomic number difference with that of the target; therefore, radiochemical separation of no-carrier-added radio-lanthanides from the target matrix becomes easier. Heavy ion induced reactions also allow the production of rare Earth radionuclides from non-rare Earth target by tailor-made target-projectile combinations, and in those cases, radiochemical separations become even more easier. In general, the cross sections of heavy ion induced reactions are less than those of light charged particle induced reactions. However, some of the heavy ion induced reactions have comparable cross sections with those of light ion induced reactions. The range of heavy ions is also much smaller in the target matrix than that of lighter charged particles. These points hinder application of heavy ion induced reactions to produce radionuclides for nuclear medicine.

Nuclear Energy Loss and Range of Heavy Ions in SiO2, LiF and Kapton Polyatomic Targets: A Monte Carlo study

Nuclear Energy Loss and Range of Heavy Ions in SiO2, LiF and Kapton Polyatomic Targets: A Monte Carlo study

Evaluation Method of Heavy-Ion-Induced Single-Event Upset in 3D-Stacked SRAMs

The interaction of radiation with three-dimensional (3D) electronic devices can be determined through the detection of single-event effects (SEU). In this study, we propose a method for the evaluation of SEUs in 3D static random-access memories (SRAMs) induced by heavy-ion irradiation. The cross-sections (CSs) of different tiers, as a function of the linear energy transfer (LET) under high, medium, and low energy heavy-ion irradiation, were obtained through Monte Carlo simulations. The simulation results revealed that the maximum value of the CS was obtained under the medium-energy heavy-ion penetration, and the effect of penetration range of heavy ions was observed in different tiers of 3D-stacked devices. The underlying physical mechanisms of charge collection under different heavy-ion energies were discussed. Thereafter, we proposed an equation of the critical heavy-ion range that can be used to obtain the worst CS curve was proposed. Considering both the LET spectra and flux of galactic cosmic ray (GCR) and the variation in the heavy-ion Bragg peak values with the atomic number, we proposed a heavy-ion irradiation test guidance for 3D-stacked devices. In addition, the effectiveness of this method was verified through simulations of the three-tier vertically stacked SRAM and the ultrahigh-energy heavy-ion irradiation experiment of the two-tier vertically stacked SRAM. this study provides a theoretical framework for the detection of SEUs induced by heavy-ion irradiation in 3D-integrated devices.

Gate Damages Induced in SiC Power MOSFETs During Heavy-Ion Irradiation—Part II

This article presents the results of a 2-D finite element simulation study of the gate damages induced by heavy-ion irradiation in SiC power metal–oxide–semiconductor field-effect transistors (MOSFETs). The time evolution of the electric field in the gate oxide is studied. Two effects are investigated: the first is associated with the charge deposition in the SiC portion of the MOSFET, with the time evolution studied using the 2-D finite element simulator; the second one results from holes generated during the ion transit, trapped in the gate oxide after the fast electrons have been quickly swept away by the electric field. Two different techniques have been combined for estimating the hole concentration in the gate oxide: the well-known recombination rate was modified to consider the trapped charge yield, as was recently done to better interpret single event gate rupture (SEGR) failure of silicon power MOSFETs. Under ion irradiation test conditions at which the gate damage experimentally starts to be observed, we demonstrate that, because of the ion impact, regardless of the ion linear energy transfer (LET), the peak value of the electric field in the gate oxide becomes practically equal to the oxide breakdown field (~12–15 MV/cm). Moreover, we show that simulations can be used to predict the test conditions at which gate damage starts to appear as a function of LET and the range of heavy ions used in the irradiation experiments.

High power density targets

In the context of new generation rare isotope beam facilities based on high-power heavy-ion accelerators and in-flight separation of the reaction products, the design of the rare isotope production targets is a major challenge. In order to provide high-purity beams for science, high resolution is required in the rare isotope separation. This demands a small beam spot on the production target which, together with the short range of heavy ions in matter, leads to very high power densities inside the target material.This paper gives an overview of the challenges associated with this high power density, discusses radiation damage issues in targets exposed to heavy ion beams, and presents recent developments to meet some of these challenges through different projects: FAIR, RIBF and FRIB which is the most challenging. Extensive use of Finite Element Analysis (FEA) has been made at all facilities to specify critical target parameters and R&D work at FRIB successfully retired two major risks related to high-power density and heavy-ion induced radiation damage.

The IGISOL technique—three decades of developments

The Ion Guide Isotope Separator On-Line (IGISOL) technique, conceived in the early 1980s as a novel variation to the helium-jet method, has been used to provide radioactive ion beams of short-lived exotic nuclei for fundamental nuclear structure research and applications for three decades. This direct on-line mass separation of primary recoil ions from nuclear reactions has achieved similar extraction efficiencies for both volatile and non-volatile elements throughout the periodic table. The evolution of the ion guide has been driven by the pursuit of physics research on both sides of the valley of beta stability. The gradual improvement in the primary beam intensities of light ions, as well as the ever increasing availability of a range of heavy ions has been matched with the development of novel ion manipulation techniques in order to maximise the output of the IGISOL facility. In this article we describe the continual development of the facility to match the needs of the scientific programme, a relationship which has proceeded hand-in-hand over the years. We will show that this strategy has been and continues to be very important for the huge success of the ion guide method for radioactive ion beam production.

Incident particle range dependence of radiation damage in a power bipolar junction transistor

The characteristic degradations in silicon NPN bipolar junction transistors (BJTs) of type 3DD155 are examined under the irradiations of 25-MeV carbon (C), 40-MeV silicon (Si), and 40-MeV chlorine (Cl) ions respectively. Different electrical parameters are measured in-situ during the exposure of heavy ions. The experimental data shows that the changes in the reciprocal of the gain variation (Δ(1/β)) of 3DD155 transistors irradiated respectively by 25-MeV C, 40-MeV Si, and 40-MeV Cl ions each present a nonlinear behaviour at a low fluence and a linear response at a high fluence. The Δ(1/β) of 3DD155 BJT irradiated by 25-MeV C ions is greatest at a given fluence, a little smaller when the device is irradiated by 40-MeV Si ions, and smallest in the case of the 40-MeV Cl ions irradiation. The measured and calculated results clearly show that the range of heavy ions in the base region of BJT affects the level of radiation damage.

Experimental stopping powers of Al, Mg, F and O ions in ZrO2 in the 0.1–0.6MeV/u energy range

The study of the stopping and range of heavy ions (Z > 3) in matter isdsc cfddc of both fundamental and practical interest as heavy ions find increasing usage in a wide range of ion beam based techniques. While semi-empirical formulations like the widely used SRIM code can predict the stopping powers of hydrogen and helium in many elemental and compound targets over a wide range of energies quite well, their predictive accuracy for heavy ions is not as good. This is mainly due to the lack of heavy ion experimental stopping power data on which such codes are based. We present results of measurements performed using a Time of Flight–Energy spectrometer to determine the stopping powers of O, F, Mg and Al ions in the oxide ceramic ZrO2 within the 0.1–0.6 MeV/u energy range. Possible SRIM correction (or correlation) factors for F, Mg and Al ions were extracted from quantitative comparisons of experimental and predicted stopping power values.

Range and etching behaviour of swift heavy ions in polymers

Aliphatic (CR-39) and aromatic (Lexan polycarbonate) polymers have been irradiated with a variety of heavy ions such as 58Ni, 93Nb, 132Xe, 139La, 197Au, 208Pb, 209Bi, and 238U having energy ranges of 5.60–8.00 MeV/n in order to study the range and etching kinetics of heavy ion tracks. The ion fluence (range ∼104–105 ions/cm2) was kept low to avoid the overlapping of etched tracks. The measured values of maximum etched track length were corrected due to bulk etching and over etching to obtain the actual range. The experimental results of range profiles were compared with those obtained by the most used procedures employed in obtaining range and stopping power. The range values of present ions have been computed using the semiempirical codes (SRIM-98, SRIM-2003.26, and LISE++:0-[Hub90]) in order to check their accuracy. The merits and demerits of the adopted formulations have been highlighted in the present work. It is observed that the range of heavy ions is greater in aromatic polymers (Lexan polycarbonate) as compared to the aliphatic polymers (CR-39) irradiated with similar ions having same incident energies. The SRIM-98 and SRIM2003.26 codes don’t show any significant trend in deviations, however, LISE++:0-[Hub90] code provides overall good agreement with the experimental values. The ratio of track etch rate (along projectile trajectory) to the bulk etch rate has also been studied as a function of energy loss of heavy ions in these polymers.

Application of MLE method to range determination with induced β + activity in hadron therapy

We proposed to apply the MLE method for determining the range of heavy ions and demonstrated the effectiveness of this method by experiments with 12C beams. We performed irradiation experiments with stable 12C ions of mono-energetic 290 MeV/u to a water, a polyethylene and a PMMA target. The theoretical ranges for 12C ions of 290 MeV/u in these targets are 160.5, 157.9 and 139.8 mm, respectively. The annihilation events from positron emitters generated by 12C ions were detected with a positron camera for 500 s just after the irradiation. To evaluate the range of 12C ions, the MLE method was applied to the annihilation gamma ray distribution. The derived ranges for the three targets were 160.6, 158.9 and 140.4 mm, respectively. Therefore, we can conclude that the range of 12C ions was determined within an accuracy of 1.0 mm for all targets.

High fluence effects on ion implantation stopping and range

We have developed a code STOPPO which can be used to modify the more-widely used ion implantation codes to more accurately predict the mean nuclear and electronic stopping power, preferential sputtering and range of heavy ions in monatomic target materials. In our simulations an effective atomic number and effective atomic mass are introduced into conveniently available analytical stopping cross-sections and a better fitting function for preferential sputtering yield is carefully evaluated for each ion implantation. The accuracy of the code confirmed experimentally by comparison with measured Rutherford backscattering spectrometry (RBS) concentration profiles for 130 keV Zr ions implanted into Be to fluences of 1 × 10 17, 2 × 10 17 and 4 × 10 17 ions/cm 2. We find a steady increase in the mean nuclear and electronic stopping powers of the target; the increase in nuclear stopping power is much greater than the increase in electronic stopping power.

Pressure effects on the stopping and range of heavy ions

Pressure effects on the energy loss of heavy ions in compound target materials are analyzed through the cores and bonds (CAB) implementation of the kinetic theory of stopping for protons and the effective charge approximation. The effect of pressure on the target material is estimated through a model of molecular confinement whereby the changes in the molecular electronic properties are calculated selfconsistently. As pressure increases, a competing behavior between target density increase and reduction in the electronic stopping cross section is observed. As a consequence, total path ranges are decreased as compared with the corresponding pressure-free target. Range calculations are shown for He + ( E⩽1.6 MeV) and Li + ( E⩽2.6 MeV) projectiles on dense water and methane targets.

Stopping power and range of heavy ions in solids: A comparative study

A comparative study of various stopping power and range formulations has been made by comparing the calculated stopping power and range values with corresponding experimental values for different projectiles, viz. H, He, Li, N, O, Al, Si, Xe, Au, Pb, Bi, U, etc. in different targets, e.g. Be, C, Al, Au, Pb, CR-39, Lexan, Mylar, LR-115, CH, (CH) n , TRIFOL-TN, etc. at various low and high energies. A detailed study has been made taking into consideration different target and projectile combinations, e.g. heavy ion-light target, light ion-heavy target and light ion-light target. Overall the Ziegler et al. ( The Stopping Power and Range of Ions in Solids, Vol. 1. Pergamon Press, New York, 1985) formulation (TRIM 95) provides the best agreement with the experimental results for all projectile and target combinations except the heavy ion-light target combination where it underestimates the stopping power data in the limited range of energy of the projectile. Mukherjee and Nayak ( Nucl. Instrum. Meth. 159, 421, 1979) formulation totally fails at relativistic and low energies of the projectile, irrespective of the projectile-target combination. Northcliffe and Schilling ( Atom. Data Nucl. Data Tables A7, 233, 1970) formulation does not show any particular trend. Benton and Henke ( Nucl. Instrum. Meth. 67, 87, 1969) formulation gives good agreement between experimental and theoretical data within the range of experimental error. The present study has been undertaken in order to determine the best stopping power and range formulation for calibration of solid state nuclear track detectors.

Range of heavy ions in solids: A comparative study

In the present work, a stack composed of two sub-stacks of CR-39 and Lexan polycarbonate sheets separated by a few A1 sheets of total thickness ≈5 mm has been exposed at an angle of 45° (w.r.t. the detector surface) to Fe, Al and N ions with energies 199, 123, 99.5 MeV/n, respectively, from the heavy ion accelerator (BEVALAC) at Berkeley, U.S.A. After opening the stack, the detector sheets were etched under optimum etching conditions and the range of these ions in the stack was determined. Theoretical calculations of range for these ions in the stack as well as for some other heavy ions (e.g. U, Au, La, Fe, Ar, Ne, N) in different media have been made using the formulations of Benton and Henke, Mukherjee and Nayak, Ziegler et al. and Hubert et al. Finally a comparison has been made with the experimental results.

Particle identification by measurement of track cone length as a function of the residual range of heavy ions in CR-39 and Lexan polycarbonate

The maximum etchable ranges of heavy ions such as 238U, 208Pb, 197Au, 132Xe and 93Nb in CR-39 and 238U, 197Au and 132Xe in Lexan polycarbonate have been determined. An attempt has been made to examine the suitability of the single-sheet particle identification technique in CR-39 and Lexan polycarbonate by plotting track cone length vs residual range for different heavy ions. A comparison has been made between experimental and theoretical values of ranges of different heavy ions in these detectors. A reasonably good agreement has been observed between the experimental and the theoretically computed values.

Experimental range of heavy ions of charge 6 ⩽ Z ⩽ 28 in CR-39 (Dop) and Lexan polycarbonate plastic track detectors

The present work describes the experimental measurement of the total etchable range for different heavy ions, 6 12C (8.7 MeV/N), 8 16O (8.7 MeV/N), 10 20Ne (7.7 MeV/N), 14 28Si (6.4 MeV/N), 26 56Fe (6.4 MeV/N) and 28 59Ni (6.5 MeV/N) in CR-39 (Dop) and Lexan polycarbonate plastic track detectors. The energy loss rate d E/d X and the range, R of these heavy ions in these detectors have also been computed theoretically using the Mukherjee and Nayak ( Nucl. Instrum. Methods 159, 421; 1979) and Benton and Henke ( Nucl. Instrum. Methods 67, 87; 1969) methods. A comparative study indicates that the experimental values of the total etchable range agree well with the corresponding theoretically computed values of the total range using the Mukherjee and Nayak method. However, the results indicate a disagreement with calculations using the Benton and Henke method. An attempt has also been made to develop empirical relations between the energy loss rate, d E/d X (calculated by using the Mukherjee and Nayak stopping power equations), the corresponding energy E, and the nuclear charge Z for different heavy ions traversing CR-39 (Dop) and Lexan polycarbonate plastic track detectors. The energy loss rate, d E/d X calculated from the Mukherjee and Nayak stopping power equations and the corresponding values predicted from empirical relations have been found to be in close agreement.

The mass dependence of the signal peak height of a Bragg-curve ionization chamber

The Bragg-curve detector of the parallel plate ionization chamber type generates a signal that is a distorted replica of the original Bragg-curve. In result of this distortion, the signal peak height is not only a function of the atomic number of the heavy ion, as it is often stated, but also of the particle mass. This mass effect was studied with the aid of computer simulation, and it was found to be dependent on the Frisch grid to anode gap width and on the detector gas. The charge resolution of the detector is affected very significantly by this mass dependence of the signal peak height. Therefore, a careful selection of the detector gas and the grid to anode gap width is necessary, if good charge resolution over a wide range of heavy ions is required.

Particle identification by measurements of track-etch rate as a function of residual range of heavy ions in biotite mica

A response curve of track-etch rate V T versus primary ionization was obtained for biotite mica, from the measurement of V T as a function of residual range of heavy ions of 10⪕Z⪕54 and energy E⪕9.6 MeV/nucleon. The data were found to be best fit by using a value of 10.1 for the fitting constant K in the primary ionization equation. The response curve of biotite reaches a plateau at J-values of about 30. It was found that the etch-rate data for Ar and S ions do not fit with the data of other ions, showing an enhancement in the track-etch rate for values of J⪕24. Profiles of track-etch rate as a function of residual range for use in particle identification studies can be constructed from these data along with a suitable range-energy relationship.

The Heidelberg Heavy Ion Postaccelerator

The Heidelberg Heavy Ion Postaccelerator, a linear accelerator booster for the upgraded MP-Tandem is operational in its extended version since end of 1979. Yielding 9.7 MV in CW and 18.5 MV in pulsed mode (duty factor 0.25) it has considerably increased the mass and energy range of heavy ions for Nuclear Physics experiments at Heidelberg. The high flexibility of the booster is guaranteed by using 32 independently phased spiral resonators allowing operation of the machine in the mass range of A=10 to A=100 with almost constant accelerating voltage; although even ions as heavy as 197Au have been successfully postaccelerated. Typical examples of postaccele-rated beams are: 164 MeV 12C, 332 MeV 32S, 476 MeV 79Br, 511 MeV 127J and 640 MeV 197Au. Longitudinal and transversal beam quality are tandem like with ?r < 2? mm mrad and ?l < 3.2? MeV .deg., the debunched energy resolution being well below 10-3. The overall availability of the postaccelerator together with the MP-Tandem was 83% of the scheduled user beam time in 1980.