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We present here simulation results of the laser-driven acceleration of gold ions using the EPOCH code. Recently, an experiment reported the acceleration of gold ions up to 7 MeV/nucleon with a strong dependency of the charge-state distribution on target thickness and the detection of the highest charge states Z ∼ 72 . Our simulations using a developmental branch of EPOCH (4.18-Ionization) show that collisional ionization is the most important cause of charge states beyond Z = 51 up to He-like Au. [ABSTRACT FROM AUTHOR]

In the past years, the interest in the laser-driven acceleration of heavy ions in the mass range of A ≈ 200 has been increasing due to promising application ideas like the fission-fusion nuclear reaction mechanism, aiming at the production of neutron-rich isotopes relevant for the astrophysical r-process nucleosynthesis. In this paper, we report on the laser acceleration of gold ions to beyond 7 MeV/u, exceeding for the first time an important prerequisite for this nuclear reaction scheme. Moreover, the gold ion charge states have been detected with an unprecedented resolution, which enables the separation of individual charge states up to 4 MeV/u. The recorded charge-state distributions show a remarkable dependency on the target foil thickness and differ from simulations, lacking a straight-forward explanation by the established ionization models. [ABSTRACT FROM AUTHOR]

An overview of the current status of the development of a nuclear clock based on the state of lowest known nuclear excitation energy in 229Th is presented. The text is especially written for the interested reader without any particular knowledge in this field of research. It is thus ideal as an introductory reading to get a broad overview of the various different aspects of the field; in addition, it can serve as a guideline for future research. An introductory part is provided, giving a historic context and explaining the fundamental concept of clocks. Finally, potential candidates for nuclear clocks other than 229Th are discussed. [ABSTRACT FROM AUTHOR]

Often, the interpretation of experiments concerning the manipulation of the energy distribution of laser-accelerated ion bunches is complicated by the multitude of competing dynamic processes simultaneously contributing to recorded ion signals. Here we demonstrate experimentally the acceleration of a clean proton bunch. This was achieved with a microscopic and three-dimensionally confined near critical density plasma, which evolves from a 1 μm diameter plastic sphere, which is levitated and positioned with micrometer precision in the focus of a Petawatt laser pulse. The emitted proton bunch is reproducibly observed with central energies between 20 and 40 MeV and narrow energy spread (down to 25%) showing almost no low-energetic background. Together with three-dimensional particle-in-cell simulations we track the complete acceleration process, evidencing the transition from organized acceleration to Coulomb repulsion. This reveals limitations of current high power lasers and viable paths to optimize laser-driven ion sources. [ABSTRACT FROM AUTHOR]

The MLLTRAP Penning trap system serves as a development environment, both for mass spectrometry as well as for novel in-trap decay-spectroscopy experiments at the MATS facility at FAIR. This contribution gives an outline on the development work done at MLLTRAP and presents the current status. [ABSTRACT FROM AUTHOR]

Presently, large efforts are conducted toward the development of highly brilliant γ beams via Compton back scattering of photons from a high-brilliance electron beam, either on the basis of a normal-conducting electron linac or a (super-conducting) Energy Recovery Linac (ERL). Particularly, ERLs provide an extremely brilliant electron beam, thus enabling the generation of highest-quality γ beams. A 2.5 MeV γ beam with an envisaged intensity of 10 photons s, as ultimately envisaged for an ERL-based γ-beam facility, narrow band width (10), and extremely low emittance (10 mm mrad) offers the possibility to produce a high-intensity bright polarized positron beam. Pair production in a face-on irradiated W converter foil (200 μm thick, 10 mm long) would lead to the emission of 2×10 (fast) positrons per second, which is four orders of magnitude higher compared to strong radioactive Na sources conventionally used in the laboratory. Using a stack of converter foils and subsequent positron moderation, a high-intensity low-energy beam of moderated positrons can be produced. Two different source setups are presented: a high-brightness positron beam with a diameter as low as 0.2 mm, and a high-intensity beam of 3×10 moderated positrons per second. Hence, profiting from an improved moderation efficiency, the envisaged positron intensity would exceed that of present high-intensity positron sources by a factor of 100. [ABSTRACT FROM AUTHOR]

We propose to produce neutron-rich nuclei in the range of the astrophysical r-process (the rapid neutron-capture process) around the waiting point N=126 (Kratz et al. in Prog. Part. Nucl. Phys. 59:147, ; Arnould et al. in Phys. Rep. 450:97, ; Panov and Janka in Astron. Astrophys. 494:829, ) by fissioning a dense laser-accelerated thorium ion bunch in a thorium target (covered by a polyethylene layer, CH), where the light fission fragments of the beam fuse with the light fission fragments of the target. Using the 'hole-boring' (HB) mode of laser radiation pressure acceleration (RPA) (Robinson et al. in Plasma Phys. Control. Fusion 51:024004, ; Henig et al. in Phys. Rev. Lett. 103:245003, ; Tajima et al. in Rev. Accel. Sci. Technol. 2:221, ) using a high-intensity, short pulse laser, bunches of Th with solid-state density can be generated very efficiently from a Th layer (ca. 560 nm thick), placed beneath a deuterated polyethylene foil (CD with ca. 520 nm), both forming the production target. Th ions laser-accelerated to about 7 MeV/u will pass through a thin CH layer placed in front of a thicker second Th foil (both forming the reaction target) closely behind the production target and disintegrate into light and heavy fission fragments. In addition, light ions (d,C) from the CD production target will be accelerated as well to about 7 MeV/u, also inducing the fission process of Th in the second Th layer. The laser-accelerated ion bunches with solid-state density, which are about 10 times more dense than classically accelerated ion bunches, allow for a high probability that generated fission products can fuse again when the fragments from the thorium beam strike the Th layer of the reaction target. In contrast to classical radioactive beam facilities, where intense but low-density radioactive beams of one ion species are merged with stable targets, the novel fission-fusion process draws on the fusion between neutron-rich, short-lived, light fission fragments from both beam and target. Moreover, the high ion beam density may lead to a strong collective modification of the stopping power in the target by 'snowplough-like' removal of target electrons, leading to significant range enhancement, thus allowing us to use rather thick targets. Using a high-intensity laser with two beams with a total energy of 300 J, 32 fs pulse length and 3 μm focal diameter, as, e.g. envisaged for the ELI-Nuclear Physics project in Bucharest (ELI-NP) (, ), order-of-magnitude estimates promise a fusion yield of about 10 ions per laser pulse in the mass range of A=180-190, thus enabling us to approach the r-process waiting point at N=126. First studies on ion acceleration, collective modifications of the stopping behaviour and the production of neutron-rich nuclei can also be performed at the upcoming new laser facility CALA (Center for Advanced Laser Applications) in Garching. [ABSTRACT FROM AUTHOR]

We propose to search for neutron halo isomers populated via γ-capture in stable nuclei with mass numbers of about A=140-180 or A=40-60, where the 4 s or 3 s neutron shell model state reaches zero binding energy. These halo nuclei can be produced for the first time with new γ-beams of high intensity and small band width (≤0.1%) achievable via Compton back-scattering off brilliant electron beams, thus offering a promising perspective to selectively populate these isomers with small separation energies of 1 eV to a few keV. Similar to single-neutron halo states for very light, extremely neutron-rich, radioactive nuclei (Hansen et al. in Annu. Rev. Nucl. Part. Sci. 45:591-634, ; Tanihata in J. Phys. G., Nucl. Part. Phys. 22:158-198, ; Aumann et al. in Phys. Rev. Lett. 84:35, ), the low neutron separation energy and short-range nuclear force allow the neutron to tunnel far out into free space much beyond the nuclear core radius. This results in prolonged half-lives of the isomers for the γ-decay back to the ground state in the 100 ps-μs range. Similar to the treatment of photodisintegration of the deuteron, the neutron release from the neutron halo isomer via a second, low-energy, intense photon beam has a known much larger cross section with a typical energy threshold behavior. In the second step, the neutrons can be released as a low-energy, pulsed, polarized neutron beam of high intensity and high brilliance, possibly being much superior to presently existing beams from reactors or spallation neutron sources. [ABSTRACT FROM AUTHOR]

The ultra-high fields of high-power short-pulse lasers are expected to contribute to understanding fundamental properties of the quantum vacuum and quantum theory in very strong fields. For example, the neutral QED vacuum breaks down at the Schwinger field strength of 1.3×1018 V/m, where a virtual e+e- pair gains its rest mass energy over a Compton wavelength and materializes as a real pair. At such an ultra-high field strength, an electron experiences an acceleration of aS=2×1028g and hence fundamental phenomena such as the long predicted Unruh effect start to play a role. The Unruh effect implies that the accelerated electron experiences the vacuum as a thermal bath with the Unruh temperature. In its accelerated frame the electron scatters photons off the thermal bath, corresponding to the emission of an entangled pair of photons in the laboratory frame. While it remains an experimental challenge to reach the critical Schwinger field strength within the immediate future even in view of the enormous thrust in high-power laser developments in recent years, the near-future laser technology may allow to probe the signatures of the Unruh effect mentioned above. Using a laser-accelerated electron beam (γ∼300) and a counter-propagating laser beam acting as optical undulator should allow to create entangled Unruh photon pairs (i.e., signatures of the Unruh effect) with energies of the order of several hundred keV. An even substantially improved experimental scenario can be realized by using a brilliant 20 keV photon beam as X-ray undulator together with a low-energy (γ≈2) electron beam. In this case the separation of the Unruh photon pairs from background originating from linearly accelerated electrons (classical Larmor radiation) is significantly improved. Detection of the Unruh photons may be envisaged by Compton polarimetry in a 2D-segmented position-sensitive germanium detector. [ABSTRACT FROM AUTHOR]

The use is suggested of a laser-accelerated dense electron sheet with an energy of ( $E=\tilde{\gamma} mc^2$) as a relativistic mirror to reflect coherently a second laser with photon energy ħω, generating by the Doppler boost high-energy γ photons with $$ \hbar \omega ' = 4\tilde \gamma ^2 \hbar \omega $$ and short duration [A. Einstein, Annalen der Physik 17, 891 (1905); D. Habs et al., Appl. Phys. B 93, 349 (2008)]. Two of these counter-propagating γ beams are focused by the parabolically shaped electron sheets into the interaction region with small, close to diffraction-limited, spot size. Comparing the new nγ-mγ collider with former proposed γγ collider schemes we achieve the conversion of many photon-pairs in a small space-time volume to matter-antimatter particles, while in the other discussed setups only two isolated, much more high-energetic photons will be converted, reaching in the new approach much higher energy densities and temperatures. With a γ-field strength somewhat below the Schwinger limit we can reach this complete conversion of the γ bunch energy into e+e- or quark-antiquark $q\bar{q}$-plasmas. For a Bose-Einstein condensate (BEC) [A. Einstein, Physikalisch-mathematische Klasse (Berlin) 22, 261 (1924); A. Einstein, Physikalisch-mathematische Klasse (Berlin) 22, 3 (1925); A. Griffin, D.W. Snoke, S. Stringari, Bose-Einstein Condensation (Cambridge University Press, 1995)] final state or for the Cooper pair ground state at higher densities [A.J. Leggett, Quantum Liquids, Oxford Graduate Texts (Oxford University Press, 2006)] the strong induced transition into this coherent state is of special interest for single-cycle γ pulses. Due to annihilation these cold coherent states are very short-lived. For γ beams with photon energies of 1–10 keV the rather cold e+e--plasma or e+e--BEC expands to a cold dense aggregate of positronium (Ps) atoms, where the production of Ps molecules is discussed. For photon energies of 1–10 MeV we discuss the production of a cold induced π0-BEC followed by the formation of molecules. For the direct population of higher $q\bar{q}$ densities we can study condensates of color-neutral mesons with enhanced population. For a γγ collider with several-cycle laser pulses the following cycles heat up the fermion-antifermion $f\bar{f}$ system to a certain temperature. Thus we can reach high energy densities and temperatures of an e+e-γ plasma, where the production of hadrons in general or the quark-gluon phase transition can be observed. Within the long-term goal of very high photon energies of about 1 GeV in the nγ-mγ-collider, even the electro-weak phase transition or SUSY phase transition could be reached. [ABSTRACT FROM AUTHOR]

A laser-accelerated dense electron sheet with an energy $E=\tilde{\gamma} mc^2$ can be used as a relativistic mirror to coherently reflect a second laser with photon energy ħω, thus generating by the Doppler boost [A. Einstein, Annalen der Physik 17, 891 (1905); D. Habs et al., Appl. Phys. B 93, 349 (2008)] brilliant high-energy photon beams with $\hbar\omega^{\prime}=4\tilde{\gamma}^2\hbar\omega$ and short duration for many new nuclear physics experiments. While the shortest-lived atomic levels are in the atto-second range, nuclear levels can have lifetimes down to zeptoseconds. We discuss how the modulation of electron energies in phase-locked laser fields used for as-measurements [E. Goulielmakis et al., Science 317, 769 (2007)] can be carried over to the new direct measurement of fs–zs nuclear lifetimes by modulating the energies of accompanying conversion electrons or emitted protons. In the field of nuclear spectroscopy we discuss the new perspective as a function of increasing photon energy. In nuclear systems a much higher sensitivity is predicted to the time variation of fundamental constants compared to atomic systems [V. Flambaum, arXiv:nucl-th/0801.1994v1 (2008)]. For energies up to 50 keV Mössbauer-like recoilless absorption allows to produce nuclear bosonic ensembles with many delocalized coherent polaritons [G.V. Smirnov et al., Phys. Rev. A 71, 023804 (2005)] for the first time. Using the ( γ, n) reaction to produce cold, polarized neutrons with a focusing ellipsoidal device [P. Böni, Nucl. Instrum. Meth. A 586, 1 (2008); Ch. Schanzer et al., Nucl. Instrum. Meth. 529, 63 (2004)], brilliant cold polarized micro-neutron beams become available. The compact and relatively cheap laser-generated γ beams may serve for extended studies at university-based facilities. [ABSTRACT FROM AUTHOR]

The MLLTRAP at the Maier-Leibnitz-Laboratory (Garching) is a new Penning trap facility designed to combine several novel technologies to decelerate, charge breed, cool, bunch and purify the reaction products and perform high-accuracy nuclear and atomic mass measurements. It is now in the commissioning phase, achieving a mass-resolving power of about 105 in the purification trap for stable ions. [ABSTRACT FROM AUTHOR]

A detailed account on the distribution of radioactive nuclei in the vacuum system of the planned Munich Accelerator for Fission Fragments (MAFF) located at the FRM-II research reactor is presented. Tools used for the simulation of spacial and temporal distribution of radionuclides are explained. The latter allows for a detailed activity budget as well as estimates for the mass-separated ion yields at MAFF. Additionally, a concept to reduce the activity release from the MAFF slit system due to surface sputtering is presented. It is shown, that the use of low-density carbon foam, as a surface coating, reduces sputtering by orders of magnitude. [ABSTRACT FROM AUTHOR]

The excitation energy spectrum of fission resonances has been measured with high energy resolution using the 235U(d,pf) reaction in order to study hyperdeformed (HD) rotational bands and HD nuclear shapes. The moments of inertia of the rotational bands and the energy of the ground state in the third minimum were determined. Another signature of these highly deformed states, their enhanced α decay, was also observed. By studying cold or compact fission in the 232Th(n,f) reaction around HD resonances, we obtained data for heavy clustering. [ABSTRACT FROM AUTHOR]

Progress in the experimental techniques used to investigate superdeformed fission isomers in the actinides allowed for detailed spectroscopic results of collective properties as well as for the identification of the rotational structure of multiphonon vibrational excitations. A novel approach could be established to determine the depth of the second potential well. [ABSTRACT FROM AUTHOR]

Neutron deficient nuclei near 100Sn have been produced by fragmentation of a 1 . AGeV 112Sn beam. The fragments were separated, identified and stopped in a highly segmented silicon strip detector stack. This detector measured the total energy of emitted β+-particles. γ-radiation was measured with surrounding detectors. The half-lives for many nuclides have been determined for the first time and give important information for the following topics: For the heaviest particle-stable odd-odd nuclei 90Rh, 94Ag and 98In we observed for the first time fast β-decays, compatible with superallowed Fermi transitions and confirmed such decays for 78Y, 82Nb and 86Tc. We have also observed long-lived T = 0 states in some of these nuclei. We measured the half-lives of all rp-process waiting-point nuclei from 80Zr up to 92, 93Pd. In addition we find the proton drip line nucleus 77Y to decay dominantly via β-decay. To study the Gamov-Teller strength in the β-decay near the doubly magic 100Sn we measured the half-life, β- and γ-spectrum of 102Sn. We propose a level scheme for the daughter nuclide 102In and deduce the Gamov-Teller strength ( BGT = 4.0±0.6). This is one of the largest values known. [ABSTRACT FROM AUTHOR]

Transitions between nuclear states with a large deformation difference may have large transition probabilities for E0 decay. Such an E0 decay has been found in the decay of the superdeformed 238U fission isomer back into the normal-deformed states [1]. However, a search for the E0 back-decay in 236U showed no result [2]. A setup has been developed to search for conversion electrons in this decay. [ABSTRACT FROM AUTHOR]

The 233U(d,pf)234U, and the 235U(d,pf)236U reactions have been studied with high energy resolution. The observed fission resonances were described as members of rotational bands with rotational parameters characteristic of hyperdeformed nuclear shapes. Information on the K values of the bands and for the J values of the band members has been obtained from fission fragment angular distribution measurements. The level density of the most strongly excited states has been compared to the prediction of the back-shifted Fermi-gas formula and the energy of the ground state in the third minimum has been estimated for 234U. The fission fragment mass distribution of the hyperdeformed states in 236U has also been measured. The width of the mass distribution, coincident with the hyperdeformed bands, is significantly smaller than the ones obtained in coincidence with background regions below and above the resonances, which suggests a pear-shaped di-nuclear configuration of 236U in the third well of the potential barrier. [ABSTRACT FROM AUTHOR]

Spectroscopic studies in the superdeformed shape isomer of 240Pu using γ-spectroscopy, conversion electron spectroscopy and transmission resonance spectroscopy have been performed. In a high-resolution and high-efficiency γ-spectroscopy experiment the out-of-band decays of several excited superdeformed rotational sequences with K=2− and 1− could be identified together with evidence for a weakly populated 0− octupole band. Surprisingly, no low-lying collective quadrupole excitations could be observed. Complementary information could be obtained in conversion electron measurements in coincidence with isomeric fission, resulting in the first identification of the lowest ß-vibrational K=0+ band. For all rotational bands the variation of the moment of inertia with spin could be studied. A predominant population of negative parity states in the second well could be observed, which can be explained by the selective population and depopulation of the second minimum. Complementary transmission resonance measurements have been performed, yielding new information on the fine structure of high-lying (ß-)vibrational multi-phonon states. A new method could be established to determine the excitation energy of the fission isomer ground state from measured level densities. [ABSTRACT FROM AUTHOR]

The ion trap facility SHIPTRAP is being set up to deliver very clean and cool beams of singly-charged recoil ions produced at the SHIP velocity filter at GSI Darmstadt. SHIPTRAP consists of a gas cell for stopping and thermalizing high-energy recoil ions from SHIP, an rf ion guide for extraction of the ions from the gas cell, a linear rf trap for accumulation and bunching of the ions, and a Penning trap for isobaric purification. The progress in testing the rf ion guide is reported. A transmission of about 93(5)% was achieved. [ABSTRACT FROM AUTHOR]

SHIPTRAP is an electromagnetic transport and trapping system to provide very clean and cold beams of singly-charged recoil ions from the SHIP facility at GSI. The different components of the system are currently under development in Munich (gas cell and extraction RFQ) and GSI (Buncher RFQ and Penning traps)[1]. Design and manufacturing of the prototype buffer gas cell and the extraction RFQ based on a wide range of simulations have been completed. The results of these simulations together with the first measurements will be reported. [ABSTRACT FROM AUTHOR]

An experiment was performed on prompt γ-ray emission in binary and α-particle accompanied spontaneous fission of 252C f using the Darmstadt-Heidelberg 4π NaI Crystal Ball spectrometer. The enhancement in γ-ray yield, denoted as the "high-energy component", which appears between 3.5 and 8 MeV and in the region of near-symmetric fragment mass splits, was observed to be equally pronounced in both fission modes. Analyzing the fragment mass dependence of the mean γ-ray multiplicity in both fission modes clearly identifies the disintegration of equilibrated fission fragments in a narrow mass range around the double-magic 132Sn as the source of these γ-rays. [ABSTRACT FROM AUTHOR]

The γ-ray spectrum ofCf(sf) was measured in the Darmstadt-Heidelberg Crystal Ball spectrometer, with a double ionization chamber mounted inside to detect the fission fragments. The measurement was aimed at a better understanding of an unusual component found in the high-energy region between 3 and 8 MeV, with fragment mass splits near symmetry. This component was proved to be predominantly emitted by the heavier fragment, to reach its highest intensity at a fragment mass split of 132:120, and to have an almost isotropic angular distribution. Calculations with the statistical code CASCADE could reproduce the main features. [ABSTRACT FROM AUTHOR]

Experiments at the Heidelberg-Darmstadt Crystal Ball have shown an increased γ-intensity in the region 3-9 MeV for fission events with one fragment near A∼132 produced in three compound nucleus fission reactionsAu(F,f),Th(O,f), andU(O,f) at 120 MeV as well as in the spontaneous fission ofCf. Trends in the data are reproduced by an empirical description based on known shell-related properties of neutron-rich nuclei northwest of the doubly magic nucleusSn. Theoretical attempts to account for the experimental results are reviewed. [ABSTRACT FROM AUTHOR]

The fission probability and the angular distribution of the associated fission fragments have been measured for the235U(d, pf)236U reaction slightly above the top of the inner fission barrier with the aim of disclosing new hyperdeformed states lying in the third minimum of the fission potential. The results are analyzed together with the data obtained from the literature for234U. The experimental resonances are interpreted as being rotational bands with rotational parameters of ħ/2Θ=1.6±0.6 and 1.8±0,8 keV for234U and236U, respectively. The K=1, 2 and 4 values of the resonances suggest that these rotational bands are built on some higher-lying excited states in the third minimum of the potential well. [ABSTRACT FROM AUTHOR]

The proton scattering on unstable38S nuclei has been measured in inverse kinematics by using a38S secondary beam at 39 MeV/nucleon. The first 2+ state is seen at 1.2 MeV excitation energy and its angular distribution is extracted. Optical and folding model calculations are compared with the elastic and the 2 angular distributions and the β2 value is determined to be 0.35±0.04. This value is compared with the corresponding result from a Coulomb excitation measurement and the M n/Mp value is extracted. [ABSTRACT FROM AUTHOR]

The MLLTRAP (Maier-Leibnitz-Laboratory TRAP) Penning trap system at the FRM-II research reactor in Munich is presented. Its planned developments to reach very high “relative atomic mass” measurement precision ( e.g., below 10-10 for stable ions) are described. [ABSTRACT FROM AUTHOR]

REX-ISOLDEis an experiment atISOLDE/CERN with the aim to study the nuclear structure of neutron-rich nuclei using radioactive ion beams up to 2.2 MeV/u. The highly-efficient γ-ray detector set-up MINIBALL will be used to explore reactions induced by Coulomb excitation or neutron transfer. [ABSTRACT FROM AUTHOR]