We report on development of a gas-jet transport system coupled to a surface ionization ion-source in the JAEA-ISOL (Isotope Separator On-Line) system. As a new aerosol material for the gas-jet ...system, CdI
2
, which has a low boiling point of 713 °C, is exploited to prevent deposition of the aerosol material on the surface of the ion-source. An additional filament is newly installed in the previous ion-source to provide uniform heating of an ionizer. The present system is applied to the measurement of absolute efficiencies of various short-lived lanthanide isotopes produced in nuclear reactions.
Continuous liquid–liquid extraction of short-lived radionuclides has traditionally been performed with the SISAK system
consisting of static mixers and H-centrifuges for phase separation. SISAK ...operates at flow rates of typically
1 mL/s. Thus, it produces large volumes of radioactive liquid waste that is difficult to dispose of. Therefore, it
has been aimed to develop and use a further miniaturised extraction unit based on microtechnology and precision engineering to
reduce the flow rate by at least two orders of magnitude. The accordingly developed MicroSISAK device is a micro membrane
extractor in which a micromixer element with 2 × 16 feed channels of 30 µm width followed by
a 60 µm high mixing chamber is used for intimately contacting the aqueous and organic phase. Subsequent phase
separation is achieved
hydrophobic Teflon membranes with a pore size of 1 µm. The MicroSISAK device has
been tested and optimized with radiotracers of the group-4 elements Zr and Hf in the system H
SO
/trioctyl amine
(TOA) in toluene. At a temperature of 58°C and a flow rate of 0.2 mL/min of both phases,
extraction yields of 87 ± 3% were achieved. The transport time from the micromixer to the first Teflon membrane was
in this case 3.9 s. It can be shortened to 1.56 s at a flow rate of 0.5 mL/min. Under similar
conditions, the extraction yield of
Tc milked from a
Mo generator in the system
HNO
/tetraphenyl arsonium chloride (TPAC) in chloroform was 83 ± 3%. In an on-line experiment at the TRIGA
Mainz reactor, short-lived Tc isotopes produced in the fission of
U with thermal neutrons were transported by
a He/KCl gas-jet to the chemistry apparatus, deposited by impaction, dissolved in 0.01 mol/L HNO
/KBrO
,
and extracted into 10
mol/L TPAC in chloroform in MicroSISAK. The separated phases were transported
capillaries to two separate flow-through cells positioned in front of two Ge detectors. The extraction yield determined as the
ratio of the Tc
-ray activities in both detectors was 76 ± 1%. With this experiment, it was demonstrated
that MicroSISAK is in principle ready for an on-line experiment for the chemical characterization of the superheavy element
bohrium, element 107. However, the detection of
-particle activities by liquid scintillation counting still needs to
be worked out.
Chemical studies of superheavy elements require fast and efficient techniques, due to short half-lives and low production rates of the
investigated nuclides. Here, we advocate for using a tubular ...flow reactor for assessing the thermal stability of the Sg carbonyl
complex – Sg(CO)
. The experimental setup was tested with Mo and W carbonyl complexes, as their properties are established
and supported by theoretical predictions. The suggested approach proved to be effective in discriminating between the thermal
stabilities of Mo(CO)
and W(CO)
. Therefore, an experimental verification of the predicted Sg–CO bond
dissociation energy seems to be feasible by applying this technique. By investigating the effect of
Mo beta-decay on
the formation of
Tc carbonyl complex, we estimated the lower reaction time limit for the metal carbonyl synthesis in
the gas phase to be more than 100 ms. We examined further the influence of the wall material of the recoil chamber, the
carrier gas composition, the gas flow rate, and the pressure on the production yield of
Mo(CO)
, so that the future
stability tests with Sg(CO)
can be optimized accordingly.
The existence of a mirror world holding a copy of our ordinary particle spectrum could lead to oscillations between the neutron (n) and its mirror partner (
n
′
). Such oscillations could manifest ...themselves in storage experiments with ultracold neutrons whose storage lifetime would depend on the applied magnetic field. Here, extended details and measurements from the first dedicated experimental search for
nn
′
oscillations published in G. Ban, K. Bodek, M. Daum, R. Henneck, S. Heule, M. Kasprzak, N. Khomutov, K. Kirch, S. Kistryn, A. Knecht, P. Knowles, M. Kuźniak, T. Lefort, A. Mtchedlishvili, O. Naviliat-Cuncic, C. Plonka, G. Quéméner, M. Rebetez, D. Rebreyend, S. Roccia, G. Rogel, M. Tur, A. Weis, J. Zejma, G. Zsigmond, Direct experimental limit on neutron mirror–neutron oscillations, Phys. Rev. Lett. 99 (2007) 161603 will be presented, focussing on a possible dependence of the UCN counts on the magnetic field and its direction. However, at present no significant change in the averaged UCN counts with respect to the applied magnetic field has been found.
Resonance ionization mass spectrometry (RIMS) is well-suited for isotope selective ultratrace analysis of long-lived radioactive isotopes due to its high element and isotope selectivity and good ...sensitivity. For the analysis of plutonium with a pulsed RIMS apparatus, a powerful, reliable and easy to handle Nd:YAG pumped titanium–sapphire laser system has been developed and combined with a time-of-flight mass spectrometer. Spectroscopic measurements led to an efficient three step excitation and ionization scheme for plutonium with
λ
1 = 420.76
nm,
λ
2 = 847.28
nm, and
λ
3 = 767.53
nm. The isotope shifts in this scheme for the plutonium isotopes
238
Pu
through
244
Pu
have been determined. An overall efficiency of the RIMS apparatus of 1 × 10
−5 is routinely achieved resulting in a detection limit of 2 × 10
6 atoms of plutonium for single isotope measurements. The application of RIMS for isotope ratio measurements is outlined.
The time-reversed reaction 15O(2p, γ)17Ne has been studied by the Coulomb dissociation technique. Secondary 17Ne ion beams at 500 AMeV have been produced by fragmentation reactions of 20Ne in a ...beryllium production target and dissociated on a secondary Pb target. The incoming beam and the reaction products have been identified with the kinematically complete LAND-R3B experimental setup at GSI. The excitation energy prior to decay has been reconstructed by using the invariant-mass method. The preliminary differential and integral Coulomb Dissociation cross sections (σCoul) have been calculated, which provide a photoabsorption (σphoto) and a radiative capture cross section (σcap). Additionally, important information about the nuclear structure of the 17Ne nucleus will be obtained. The analysis is in progress.
The proton drip-line nucleus Ne-17 is investigated experimentally in order to determine its two-proton halo character. A fully exclusive measurement of the Ne-17(p, 2p)F-16* -> O-15+p quasi-free ...one-proton knockout reaction has been performed at GSI at around 500MeV/nucleon beam energy. All particles resulting from the scattering process have been detected. The relevant reconstructed quantities are the angles of the two protons scattered in quasi-elastic kinematics, the decay of F-16 into O-15 (including gamma decays from excited states) and a proton, as well as the O-15+p relative-energy spectrum and the F-16 momentum distributions. The latter two quantities allow an independent and consistent determination of the fractions of l = 0 and l = 2 motion of the valence protons in Ne-17. With a resulting relatively small l = 0 component of only around 35(3)%, it is concluded that Ne-17 exhibits a rather modest halo character only. The quantitative agreement of the two values deduced from the energy spectrum and the momentum distributions supports the theoretical treatment of the calculation of momentum distributions after quasi-free knockout reactions at high energies by taking into account distortions based on the Glauber theory. Moreover, the experimental data allow the separation of valence-proton knockout and knockout from the O-15 core. The latter process contributes with 11.8(3.1) mb around 40% to the total proton-knockout cross section of 30.3(2.3) mb, which explains previously reported contradicting conclusions derived from inclusive cross sections. (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP(3).
The electron-capture decay followed by a prompt fission process was searched for in the hitherto unknown most neutron-deficient Md isotope with mass number 244. Alpha decay with α -particle energies ...of 8.73–8.86 MeV and with a half-life of ... s was assigned to 244Md. No fission event with a similar half-life potentially originating from spontaneous fissioning of the short-lived electron-capture decay daughter 244Fm was observed, which results in an upper limit of 0.14 for the electron-capture branching of 244Md. Two groups of fission events with half-lives of ... ms and ... ms were observed. The ... ms activity was assigned to originate from the decay of 245Md. The origin of eight fission events resulting in a half-life of ms could not be unambiguously identified within the present data while the possible explanation has to invoke previously unseen physics cases. (ProQuest: ... denotes formulae omited.).
The proton drip-line nucleus 17Ne is investigated experimentally in order to determine its two-proton halo character. A fully exclusive measurement of the 17Ne(p,2p)16F→15⁎O+p quasi-free one-proton ...knockout reaction has been performed at GSI at around 500 MeV/nucleon beam energy. All particles resulting from the scattering process have been detected. The relevant reconstructed quantities are the angles of the two protons scattered in quasi-elastic kinematics, the decay of 16F into 15O (including γ decays from excited states) and a proton, as well as the 15O+p relative-energy spectrum and the 16F momentum distributions. The latter two quantities allow an independent and consistent determination of the fractions of l=0 and l=2 motion of the valence protons in 17Ne. With a resulting relatively small l=0 component of only around 35(3)%, it is concluded that 17Ne exhibits a rather modest halo character only. The quantitative agreement of the two values deduced from the energy spectrum and the momentum distributions supports the theoretical treatment of the calculation of momentum distributions after quasi-free knockout reactions at high energies by taking into account distortions based on the Glauber theory. Moreover, the experimental data allow the separation of valence-proton knockout and knockout from the 15O core. The latter process contributes with 11.8(3.1) mb around 40% to the total proton-knockout cross section of 30.3(2.3) mb, which explains previously reported contradicting conclusions derived from inclusive cross sections.
PDF
