Introducing the Fission-Fusion Reaction Process: Using a Laser-Accelerated Th Beam to produce Neutron-Rich Nuclei towards the N=126 Waiting Point of the r Process

We propose to produce neutron-rich nuclei in the range of the astrophysical r-process around the waiting point N=126 by fissioning a dense laser-accelerated thorium ion bunch in a thorium target (covered by a CH2 layer), where the light fission fragments of the beam fuse with the light fission fragments of the target. Via the 'hole-boring' mode of laser Radiation Pressure Acceleration using a high-intensity, short pulse laser, very efficiently bunches of 232Th with solid-state density can be generated from a Th layer, placed beneath a deuterated polyethylene foil, both forming the production target. Th ions laser-accelerated to about 7 MeV/u will pass through a thin CH2 layer placed in front of a thicker second Th foil closely behind the production target and disintegrate into light and heavy fission fragments. In addition, light ions (d,C) from the CD2 production target will be accelerated as well to about 7 MeV/u, inducing the fission process of 232Th also in the second Th layer. The laser-accelerated ion bunches with solid-state density, which are about 10^14 times more dense than classically accelerated ion bunches, allow for a high probability that generated fission products can fuse again. In contrast to classical radioactive beam facilities, where intense but low-density radioactive beams are merged with stable targets, the novel fission-fusion process draws on the fusion between neutron-rich, short-lived, light fission fragments both from beam and target. The high ion beam density may lead to a strong collective modification of the stopping power in the target, leading to significant range enhancement. Using a high-intensity laser as envisaged for the ELI-Nuclear Physics project in Bucharest (ELI-NP), estimates promise a fusion yield of about 10^3 ions per laser pulse in the mass range of A=180-190, thus enabling to approach the r-process waiting point at N=126.Comment: 13 pages, 6 figure

Learning Outcomes of an Educational Leadership Cohort Program

Over the past three decades, demands on public schools have increased dramatically with a direct impact on the expectations of principals

Azamacrocyclic Ca2+ Sensitive Contrast Agents for MR Imaging

As calcium plays an important role in regulating a great variety of neuronal processes, many efforts are already made to generate gadolinium complexes that can act as a calcium-sensors in MRI.1 We developed a series of the DO3A-based macrocyclic and bismacrocyclic gadolinium chelates, bearing phosphonate groups as an additional coordination sites. These complexes are hypothesized to change the MRI contrast dynamically with Ca2+ concentration. Different lengths of the phosphonate side chains are exploited for fine-tuning the sensitivity of the agent to calcium ion concentration

Efficient ion acceleration by collective laser-driven electron dynamics with ultra-thin foil targets

Experiments on ion acceleration by irradiation of ultra-thin diamond-like carbon (DLC) foils, with thicknesses well below the skin depth, irradiated with laser pulses of ultra-high contrast and linear polarization, are presented. A maximum energy of 13MeV for protons and 71MeV for carbon ions is observed with a conversion efficiency of > 10%. Two-dimensional particle-in-cell (PIC) simulations reveal that the increase in ion energies can be attributed to a dominantly collective rather than thermal motion of the foil electrons, when the target becomes transparent for the incident laser pulse

Downward continued multichannel seismic refraction analysis of Atlantis Massif oceanic core complex, 30°N, Mid-Atlantic Ridge

Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 13 (2012): Q0AG07, doi:10.1029/2012GC004059.Detailed seismic refraction results show striking lateral and vertical variability of velocity structure within the Atlantis Massif oceanic core complex (OCC), contrasting notably with its conjugate ridge flank. Multichannel seismic (MCS) data are downward continued using the Synthetic On Bottom Experiment (SOBE) method, providing unprecedented detail in tomographic models of the P-wave velocity structure to subseafloor depths of up to 1.5 km. Velocities can vary up to 3 km/s over several hundred meters and unusually high velocities (~5 km/s) are found immediately beneath the seafloor in key regions. Correlation with in situ and dredged rock samples, video and records from submersible dives, and a 1.415 km drill core, allow us to infer dominant lithologies. A high velocity body(ies) found to shoal near to the seafloor in multiple locations is interpreted as gabbro and is displaced along isochrons within the OCC, indicating a propagating magmatic source as the origin for this pluton(s). The western two-thirds of the Southern Ridge is capped in serpentinite that may extend nearly to the base of our ray coverage. The distribution of inferred serpentinite indicates that the gabbroic pluton(s) was emplaced into a dominantly peridotitic host rock. Presumably the mantle host rock was later altered via seawater penetration along the detachment zone, which controlled development of the OCC. The asymmetric distribution of seismic velocities and morphology of Atlantis Massif are consistent with a detachment fault with a component of dip to the southeast. The lowest velocities observed atop the eastern Central Dome and conjugate crust are most likely volcanics. Here, an updated model of the magmatic and extensional faulting processes at Atlantis Massif is deduced from the seismic results, contributing more generally to understanding the processes controlling the formation of heterogeneous lithosphere at slow-rate spreading centers.NSF support was provided via grant OCE-0927442.2012-11-1

Giant half-cycle attosecond pulses

Half-cycle picosecond pulses have been produced from thin photo-conductors, when applying an electric field across the surface and switching on conduction by a short laser pulse. Then the transverse current in the wafer plane emits half-cycle pulses in normal direction, and pulses of 500 fs duration and 1e6 V/m peak electric field have been observed. Here we show that single half-cycle pulses of 50 as duration and up to 1e13 V/m can be produced when irradiating a double foil target by intense few-cycle laser pulses. Focused onto an ultra-thin foil, all electrons are blown out, forming a uniform sheet of relativistic electrons. A second layer, placed at some distance behind, reflects the drive beam, but lets electrons pass straight. Under oblique incidence, beam reflection provides the transverse current, which emits intense half-cycle pulses. Such a pulse may completely ionize even heavier atoms. New types of attosecond pump-probe experiments will become possible.Comment: 5 pages, 4 figures, to be presented at LEI2011-Light at Extreme Intensities and China-Germany Symposium on Laser Acceleratio

Dynamics of Nanometer-Scale Foil Targets Irradiated with Relativistically Intense Laser Pulses

In this letter we report on an experimental study of high harmonic radiation generated in nanometer-scale foil targets irradiated under normal incidence. The experiments constitute the first unambiguous observation of odd-numbered relativistic harmonics generated by the $\vec{v}\times\vec{B}$ component of the Lorentz force verifying a long predicted property of solid target harmonics. Simultaneously the observed harmonic spectra allow in-situ extraction of the target density in an experimental scenario which is of utmost interest for applications such as ion acceleration by the radiation pressure of an ultraintense laser.Comment: 5 pages, 4 figure

PADC nuclear track detector for ion spectroscopy in laser-plasma acceleration

[EN] The transparent polymer polyallyl-diglycol-carbonate (PADC), also known as CR-39, is widely used as detector for heavy charged particles at low fluence. It allows for detection of single protons and ions via formation of microscopic tracks after etching in NaOH or KOH solutions. PADC combines a high sensitivity and high specificity with inertness towards electromagnetic noise. Present fields of application include laser-ion acceleration, inertial confinement fusion, radiobiological studies with cell cultures, and dosimetry of nuclear fragments in particle therapy. These require precise knowledge of the energy-dependent response of PADC to different ion species. We present calibration data for a new type of detector material, Radosys RS39, to protons (0.2-3 MeV) and carbon ions (0.6-12 MeV). RS39 is less sensitive to protons than other types of PADC. Its response to carbon ions, however, is similar to other materials. Our data indicate that RS39 allows for measuring carbon ion energies up to 10 MeV only from the track diameters. In addition, it can be used for discrimination between protons and carbon ions in a single etching process.Project funded by CSIC, Grant No. 2018501082, and by the Spanish Ministerio de Ciencia, Innovacion y Universidades, project MdM-2016-0692-17-2 via a predoctoral grant of type Maria de Maeztu FPI. Nuclear track detector material and readout equipment have been provided by Radosys Ldt. (Budapest). The authors acknowledge the contributions and commitment of the CNA accelerator operators. MS would like to thank L. Ballesteros and J. Ortiz for their support with precision equipment.Seimetz, M.; Peñas, J.; Llerena, JJ.; Benlliure, J.; García López, J.; Millán-Callado, MA.; Benlloch Baviera, JM. (2020). PADC nuclear track detector for ion spectroscopy in laser-plasma acceleration. Physica Medica. 76:72-76. https://doi.org/10.1016/j.ejmp.2020.06.005S727676Kodaira, S., Kitamura, H., Kurano, M., Kawashima, H., & Benton, E. R. (2019). Contribution to dose in healthy tissue from secondary target fragments in therapeutic proton, He and C beams measured with CR-39 plastic nuclear track detectors. Scientific Reports, 9(1). doi:10.1038/s41598-019-39598-0Scampoli, P., Casale, M., Durante, M., Grossi, G., Pugliese, M., & Gialanella, G. (2001). Low-energy light ion irradiation beam-line for radiobiological studies. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 174(3), 337-343. doi:10.1016/s0168-583x(00)00622-4WADA, S., KOBAYASHI, Y., FUNAYAMA, T., NATSUHORI, M., ITO, N., & YAMAMOTO, K. (2002). Detection of DNA Damage in Individual Cells Induced by Heavy-ion Irradiation with an Non-denaturing Comet Assay. Journal of Radiation Research, 43(S), S153-S156. doi:10.1269/jrr.43.s153Gaillard, S., Pusset, D., de Toledo, S. M., Azzam, E. I., & Fromm, M. (2008). Distance distribution of bystander effects in alpha-particle irradiated cell populations using a CR-39-based culture dish. Radiation Measurements, 43, S34-S40. doi:10.1016/j.radmeas.2008.03.063Yogo, A., Maeda, T., Hori, T., Sakaki, H., Ogura, K., Nishiuchi, M., … Kondo, K. (2011). Measurement of relative biological effectiveness of protons in human cancer cells using a laser-driven quasimonoenergetic proton beamline. Applied Physics Letters, 98(5), 053701. doi:10.1063/1.3551623Séguin, F. H., Frenje, J. A., Li, C. K., Hicks, D. G., Kurebayashi, S., Rygg, J. R., … Padalino, S. (2003). Spectrometry of charged particles from inertial-confinement-fusion plasmas. Review of Scientific Instruments, 74(2), 975-995. doi:10.1063/1.1518141Daido, H., Nishiuchi, M., & Pirozhkov, A. S. (2012). Review of laser-driven ion sources and their applications. Reports on Progress in Physics, 75(5), 056401. doi:10.1088/0034-4885/75/5/056401Sinenian, N., Rosenberg, M. J., Manuel, M., McDuffee, S. C., Casey, D. T., Zylstra, A. B., … Petrasso, R. D. (2011). The response of CR-39 nuclear track detector to 1–9 MeV protons. Review of Scientific Instruments, 82(10), 103303. doi:10.1063/1.3653549Malinowska A, Szydłowski A, Jaskóła M, Korman A, Sartowska B, Kuehn T, Kuk M. Investigations of protons passing through the CR-39/PM-355 type of solid state nuclear track detectors, Rev Sci Instrum 84 (2013) 073511.Baccou, C., Yahia, V., Depierreux, S., Neuville, C., Goyon, C., Consoli, F., … Labaune, C. (2015). CR-39 track detector calibration for H, He, and C ions from 0.1-0.5 MeV up to 5 MeV for laser-induced nuclear fusion product identification. Review of Scientific Instruments, 86(8), 083307. doi:10.1063/1.4927684Seimetz, M., Bellido, P., García, P., Mur, P., Iborra, A., Soriano, A., … Benlloch, J. M. (2018). Spectral characterization of laser-accelerated protons with CR-39 nuclear track detector. Review of Scientific Instruments, 89(2), 023302. doi:10.1063/1.5009587Xiaojiao, D., Xiaofei, L., Zhixin, T., Yongsheng, H., Shilun, G., Dawei, Y., & Naiyan, W. (2009). Calibration of CR-39 with monoenergetic protons. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 609(2-3), 190-193. doi:10.1016/j.nima.2009.08.061Kodaira, S., Morishige, K., Kawashima, H., Kitamura, H., Kurano, M., Hasebe, N., … Ogura, K. (2016). A performance test of a new high-surface-quality and high-sensitivity CR-39 plastic nuclear track detector – TechnoTrak. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 383, 129-135. doi:10.1016/j.nimb.2016.07.002Ogura, K., Asano, M., Yasuda, N., & Yoshida, M. (2001). Properties of TNF-1 track etch detector. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 185(1-4), 222-227. doi:10.1016/s0168-583x(01)00816-3Malinowska, A., Jaskóła, M., Korman, A., Szydłowski, A., & Kuk, M. (2014). Characterization of solid state nuclear track detectors of the polyallyl-diglycol-carbonate (CR-39/PM-355) type for light charged particle spectroscopy. Review of Scientific Instruments, 85(12), 123505. doi:10.1063/1.4903755Bahrami, F., Mianji, F., Faghihi, R., Taheri, M., & Ansarinejad, A. (2016). Response of CR-39 to 0.9–2.5 MeV protons for KOH and NaOH etching solutions. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 813, 96-101. doi:10.1016/j.nima.2016.01.015Jeong, T. W., Singh, P. K., Scullion, C., Ahmed, H., Hadjisolomou, P., Jeon, C., … Ter-Avetisyan, S. (2017). CR-39 track detector for multi-MeV ion spectroscopy. Scientific Reports, 7(1). doi:10.1038/s41598-017-02331-wKanasaki, M., Hattori, A., Sakaki, H., Fukuda, Y., Yogo, A., Jinno, S., … Yamauchi, T. (2013). A high energy component of the intense laser-accelerated proton beams detected by stacked CR-39. Radiation Measurements, 50, 46-49. doi:10.1016/j.radmeas.2012.10.009Groza, A., Serbanescu, M., Butoi, B., Stancu, E., Straticiuc, M., Burducea, I., … Ganciu, M. (2019). Advances in Spectral Distribution Assessment of Laser Accelerated Protons using Multilayer CR-39 Detectors. Applied Sciences, 9(10), 2052. doi:10.3390/app9102052Zhang, Y., Wang, H.-W., Ma, Y.-G., Liu, L.-X., Cao, X.-G., Fan, G.-T., … Fang, D.-Q. (2019). Energy calibration of a CR-39 nuclear-track detector irradiated by charged particles. Nuclear Science and Techniques, 30(6). doi:10.1007/s41365-019-0619-xSeimetz, M., Bellido, P., Soriano, A., Garcia Lopez, J., Jimenez-Ramos, M. C., Fernandez, B., … Benlloch, J. M. (2015). Calibration and Performance Tests of Detectors for Laser-Accelerated Protons. IEEE Transactions on Nuclear Science, 62(6), 3216-3224. doi:10.1109/tns.2015.2480682Rana, M. A., & Qureshi, I. . (2002). Studies of CR-39 etch rates. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 198(3-4), 129-134. doi:10.1016/s0168-583x(02)01526-4Hermsdorf, D., Hunger, M., Starke, S., & Weickert, F. (2007). Measurement of bulk etch rates for poly-allyl-diglycol carbonate (PADC) and cellulose nitrate in a broad range of concentration and temperature of NaOH etching solution. Radiation Measurements, 42(1), 1-7. doi:10.1016/j.radmeas.2006.06.009Azooz, A. A., & Al-Jubbori, M. A. (2013). Interrelated temperature dependence of bulk etch rate and track length saturation time in CR-39 detector. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 316, 171-175. doi:10.1016/j.nimb.2013.09.001Jadrníčková I, Spurný F. To the spectrometry of linear energy transfer in charged particle beams by means of track-etch detectors, Radiat Measure 43(2008): S191–S194, proceedings of the 23rd International Conference on Nuclear Tracks in Solids. doi: 10.1016/j.radmeas.2008.04.010.Sadowski, M., Al-Mashhadani, E. M., Szydłowski, A., Czyzewski, T., Głowacka, L., Jaskóła, M., … Wieluński, M. (1995). Comparison of responses of CR-39 and PM-355 track detectors to fast protons, deuterons and 4He ions within energy range 0.2–4.5 MeV. Radiation Measurements, 25(1-4), 175-176. doi:10.1016/1350-4487(95)00066-nSadowski, M., Szydlowski, A., Jaskola, M., Czyzewski, T., & Kobzev, A. P. (1997). Comparison of responses of CR-39, PM-355, and CN track detectors to energetic hydrogen-, helium-, nitrogen-, and oxygen-ions. Radiation Measurements, 28(1-6), 207-210. doi:10.1016/s1350-4487(97)00069-3Henig, A., Steinke, S., Schnürer, M., Sokollik, T., Hörlein, R., Kiefer, D., … Habs, D. (2009). Radiation-Pressure Acceleration of Ion Beams Driven by Circularly Polarized Laser Pulses. Physical Review Letters, 103(24). doi:10.1103/physrevlett.103.245003Kar, S., Kakolee, K. F., Qiao, B., Macchi, A., Cerchez, M., Doria, D., … Borghesi, M. (2012). Ion Acceleration in Multispecies Targets Driven by Intense Laser Radiation Pressure. Physical Review Letters, 109(18). doi:10.1103/physrevlett.109.185006Palaniyappan, S., Huang, C., Gautier, D. C., Hamilton, C. E., Santiago, M. A., Kreuzer, C., … Fernández, J. C. (2015). Efficient quasi-monoenergetic ion beams from laser-driven relativistic plasmas. Nature Communications, 6(1). doi:10.1038/ncomms10170McGuffey, C., Raymond, A., Batson, T., Hua, R., Petrov, G. M., Kim, J., … Beg, F. N. (2016). Acceleration of high charge-state target ions in high-intensity laser interactions with sub-micron targets. New Journal of Physics, 18(11), 113032. doi:10.1088/1367-2630/18/11/113032Ma, W. J., Kim, I. J., Yu, J. Q., Choi, I. W., Singh, P. K., Lee, H. W., … Nam, C. H. (2019). Laser Acceleration of Highly Energetic Carbon Ions Using a Double-Layer Target Composed of Slightly Underdense Plasma and Ultrathin Foil. Physical Review Letters, 122(1). doi:10.1103/physrevlett.122.014803Hegelich, M., Karsch, S., Pretzler, G., Habs, D., Witte, K., Guenther, W., … Roth, M. (2002). MeV Ion Jets from Short-Pulse-Laser Interaction with Thin Foils. Physical Review Letters, 89(8). doi:10.1103/physrevlett.89.085002Henig, A., Kiefer, D., Markey, K., Gautier, D. C., Flippo, K. A., Letzring, S., … Hegelich, B. M. (2009). Enhanced Laser-Driven Ion Acceleration in the Relativistic Transparency Regime. Physical Review Letters, 103(4). doi:10.1103/physrevlett.103.045002Carroll, D. C., Tresca, O., Prasad, R., Romagnani, L., Foster, P. S., Gallegos, P., … McKenna, P. (2010). Carbon ion acceleration from thin foil targets irradiated by ultrahigh-contrast, ultraintense laser pulses. New Journal of Physics, 12(4), 045020. doi:10.1088/1367-2630/12/4/045020Jung, D., Yin, L., Albright, B. J., Gautier, D. C., Letzring, S., Dromey, B., … Hegelich, B. M. (2013). Efficient carbon ion beam generation from laser-driven volume acceleration. New Journal of Physics, 15(2), 023007. doi:10.1088/1367-2630/15/2/023007Dollar, F., Zulick, C., Matsuoka, T., McGuffey, C., Bulanov, S. S., Chvykov, V., … Krushelnick, K. (2013). High contrast ion acceleration at intensities exceeding 1021 Wcm−2. Physics of Plasmas, 20(5), 056703. doi:10.1063/1.4803082Kohno, R., Yasuda, N., Takeshi, H., Kase, Y., Ochiai, K., Komori, M., … Kanai, T. (2005). Measurements of Dose-Averaged Linear Energy Transfer Distributions in Water Using CR-39 Plastic Nuclear Track Detector for Therapeutic Carbon Ion Beams. Japanese Journal of Applied Physics, 44(12), 8722-8726. doi:10.1143/jjap.44.8722Romo, V., Rickards, J., Espinosa, G., & Golzarri, J. I. (1999). The Response of CR-39 Polycarbonate to Energetic Carbon Ions. Radiation Protection Dosimetry, 85(1), 459-461. doi:10.1093/oxfordjournals.rpd.a032897Szydlowski, A., Czyzewski, T., Jaskola, M., Sadowski, M., Korman, A., Kedzierski, J., & Kretschmer, W. (1999). Investigation of response of CR-39, PM-355 and PM-500 types of nuclear track detectors to energetic carbon ions. Radiation Measurements, 31(1-6), 257-260. doi:10.1016/s1350-4487(99)00125-

Theory of laser ion acceleration from a foil target of nanometers

A theory for laser ion acceleration is presented to evaluate the maximum ion energy in the interaction of ultrahigh contrast (UHC) intense laser with a nanometer-scale foil. In this regime the energy of ions may be directly related to the laser intensity and subsequent electron dynamics. This leads to a simple analytical expression for the ion energy gain under the laser irradiation of thin targets. Significantly, higher energies for thin targets than for thicker targets are predicted. Theory is concretized to the details of recent experiments which may find its way to compare with these results.Comment: 22 pages 7 figures. will be submitted to NJ

Laser Ion Acceleration: Status and Perspectives for Fusion

High power short-pulse lasers presently reach peak powers of a few hundred Terawatts up to a Petawatt, and routinely reach focal intensities of 1018 - 1021 W/cm2 . These lasers are able to produce various secondary radiation, from relativistic electrons and multi-MeV/nucleon ions to high-energetic X-rays and γ-rays. In many laboratories world-wide large efforts are presently devoted to a rapid development of this novel tool of particle acceleration, targeting nuclear, fundamental and high-field physics studies as well as various applications. Based on the Radiation Pressure Acceleration mechanism, laser-accelerated ion beams can be generated with solid-state density, thus exceeding beams from conventional accelerators by about 14 orders of magnitudes. This opens the perspective of a novel reaction scheme called ’f ssion-fusion’, where in a first step f ssion is induced both in laser-accelerated f ssile projectiles from a ’production target’ and in a second ’reaction target’ again from f ssile material hit by the accelerated projectiles. Due to the unprecedented ion density, (neutron-rich) light f ssion fragments from projectile and target can fuse again, forming extremely exotic species approaching the region of the N = 126 waiting point of the r-process. Within the next 5 years a new EU-funded large-scale research infrastructure (ELI: Extreme Light Infrastructure) will be constructed, with one of its four pillars exclusively devoted to nuclear physics based on high intensity lasers (ELI-Nuclear Physics, to be built in Magurele/Bucharest). Studies of laser-induced nuclear reactions like the ’f ssion-fusion’ mechanism will be amongst the experimental f agship projects pursued there