Spectroscopy of [sub 199,201]At

The excited states of 199At and 201At were studied using fusion evaporation reactions, a gas-filled recoil separator and various tagging methods. The level scheme of 201At was extended a lot including a cascade of magnetic dipole transitions, that is suggested to form a shears band. In addition, a 29/2+ [T1/2 = 3.39(9) s] isomeric state was observed. The 29/2+ state is suggested to originate from the p(h9/2) j200Po; 11i configuration, and it depopulates through 269-keV E2 and 339-keV E3 transitions. In both nuclei 199,201At we have observed also the isomeric 1/2+ [T1/2 = 273(9), 45(3) ms, respectively] intruder state, that is suggested to originate from the p(s1/2)1 configuration. The 1/2+ state decays through 103- keV and 269-keV E3 transitions in 199,201At, respectively. In both nuclei the 1/2+ state is fed from 3/2+ and 5/2+ states, which are suggested to originate from the p(d3/2)1 and p(d5/2)1 configurations, respectively

Energeettisten protonien jarruuntuminen nestemäisessä vedessä

Tämän työn tarkoituksena oli mitata protonien jarruuntumiskyky nestemäisessä vedessä energia-alueella 4 - 20 MeV. Työssä käytettiin micro channel plate -pohjaisia lentoaikailmaisimia. Lopputulosten suhteelliset virheet vaihtelivat välillä 2,0 - 16,5 % mediaanin ollessa 4,2 % ja keskiarvon 5,3 %. Saadut tulokset olivat hyvässä sopusoinnussa ICRU:n raportin numero 49 antamien simuloitujen arvojen kanssa. Energialtaan 4 - 16 MeV protonien mitatut jarruuntumiskyvyt poikkesivat noin yhden prosentin tai vähemmän simuloiduista arvoista. Energia-alueella 16 - 20 MeV protonien mitatut jarruuntumiskyvyt olivat noin 4 - 8 % suuremmat kuin ICRU:n antamat simuloidut arvot. Mitattuja arvoja verrattiin myös SRIM-2008.04 -ohjelmalla simuloituihin arvoihin. Energialtaan 9 - 20 MeV protonien jarruuntumiskyvyt olivat sopusoinnussa SRIM:n antamien arvojen kanssa. Kuitenkin tätä pienemmillä energioilla SRIM:n simuloimat jarruuntumiskyvyt olivat noin 3 % suuremmat kuin mitatut arvot, ja nämä arvot eivät olleet sopusoinnussa mitattujen arvojen kanssa

Expression of the miR-200 family in tumor tissue, plasma and urine of epithelial ovarian cancer patients in comparison to benign counterparts

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Determination of absolute internal conversion coefficients using the SAGE spectrometer

A non-reference based method to determine internal conversion coefficients using the SAGE spectrometer is carried out for transitions in the nuclei of 154Sm, 152Sm and 166Yb. The Normalised-Peak-to-Gamma method is in general an efficient tool to extract internal conversion coefficients. However, in many cases the required well-known reference transitions are not available. The data analysis steps required to determine absolute internal conversion coefficients with the SAGE spectrometer are presented. In addition, several background suppression methods are introduced and an example of how ancillary detectors can be used to select specific reaction products is given. The results obtained for ground-state band E2 transitions show that the absolute internal conversion coefficients can be extracted using the methods described with a reasonable accuracy. In some cases of less intense transitions only an upper limit for the internal conversion coefficient could be given.peerReviewe

Fusion-induced fission measurements with the MUSIC active target detector

The rapid neutron capture process (r-process) is believed to be responsible for about half of the production of the elements heavier than iron and it may also contribute to abundances of some lighter nuclides. Great excitement was recently generated by evidence for r-process nucleosynthesis in binary neutron star mergers via multi-wavelength observations of kilonova emission and gravitational waves. In order to interpret the observations and validate theoretical predictions, an understanding of the fission process, in particular of the evolution of fission barrier heights, is needed. An experimental study of fusioninduced fission cross sections using active-target detectors is a promising idea since the fission excitation function can be studied with a single beam energy. The Multi-Sampling Ionization Chamber (MUSIC) is an active-target detector in which a gas serves as both, counting gas and target nuclei. A proof-of principle experiment to explore the ability to identify fission events with MUSIC was recently performed at Argonne National Laboratory. In this work, ideas, results and perspectives will be discussed

Spectroscopy of the proton drip-line nucleus 203Fr

The nucleus 203Fr has been studied through γ -ray and electron spectroscopy, using the recoil-decay tagging technique. A 13/2+ state, with a half-life of 0.37(5) μs, has been observed in 203Fr. Both the α-decay branch and the internal de-excitation of the 1/2+ isomer in 203Fr have been studied. Furthermore, the corresponding 1/2+ state, with a half-life of 0.31(8) s, has been found in 199At. In addition, transitions feeding the 9/2− ground state of 203Fr have been identified. The observed level pattern suggests that the ground state is still spherical.peerReviewe

Confirmation of the new isotope 178Pb

The extremely neutron-deficient isotope 178Pb has been produced. The GREAT spectrometer at the focal plane position of the gas-filled separator RITU was used to study the α decay of 178Pb and its α-decay chain through α-α correlations. The α decay was measured to have an energy and half-life of Eα= 7610(30) keV and t1/2 = 0.21+0.21 −0.08 ms, respectively. The half-life is consistent with recent theoretical calculations using the Coulomb and proximity potential model. The α-decay reduced width and hindrance factor for 178Pb were deduced and correspond to an unhindered l = 0 transition. In addition, the mass excess of 178Pb and the α-decay Q value were calculated from the experimental results and compared to theoretical values.peerReviewe

Experimental study of 1/2(+) isomers in At-199,At-201

Using fusion-evaporation reactions, a gas-filled recoil separator, and recoil-electron and recoil-electron-α tagging techniques, a new isomeric 1 2 + state [T1/2 = 45(3) ms] in 201At is identified, and an earlier reported corresponding state [T1/2 = 273(9) ms] in 199At is confirmed. The 1 2 + state is suggested to originate from an intruder π(s1/2) −1 configuration. In addition, nuclear structure of states below and above this 1 2 + state are studied in both nuclei. The isomer decays through a cascade of an E3 transition followed by a mixed M1/E2 transition to the 9 2 − ground state, and it is interpreted to be fed from nearly spherical 3 2 + and 5 2 + states originating from π(d3/2) −1 and π(d5/2) −1 configurations, respectively.peerReviewe

Decay spectroscopy of 179 82 Pb 97 and evidence for a 9/2− intruder state in 179 81 Tl 98

The very neutron-deficient isobars 179Pb and 179Tl have been produced using the fusion-evaporation reactions 104Pd(78Kr,xpyn), where x≤1 and y≥2. The gas-filled separator RITU was employed to transport and separate the recoiling nuclei of interest from the scattered beam and unwanted products. The GREAT spectrometer was used to study the decay properties through α−α and α−γ correlations, which has allowed the ground state of 179Pb to be assigned as Iπ=9/2−. The decay of 179Pb was measured to have an α-particle energy and half-life of Eα=7348(5)keV and t1/2=2.7(2) ms, respectively. A search for a νi13/2 state in 179Pb was performed, but only a limit of excitation energy and half-life was obtained. In 179Tl a t1/2=114+18−10 ns isomeric state, likely at an excitation energy of 904.5(9) keV, was identified and is tentatively assigned to be a 9/2− proton intruder state.peerReviewe

Experimental study of isomeric intruder ½+ states 197,203At

A newly observed isomeric intruder ½ + state [ T ½ = 3.5 ( 6 ) ms ] is identified in 203 At using a gas-filled recoil separator and fusion-evaporation reactions. The isomer is depopulated through a cascade of E 3 and mixed M 1 / E 2 transitions to the 9 / 2 − ground state, and it is suggested to originate from the π ( s ½ ) − 1 configuration. In addition, the structures above the ½ + state in 203 At and 197 At are studied using in-beam γ -ray spectroscopy, recoil-decay tagging, and recoil-isomer decay tagging methods. The ½ + state is fed from 3 / 2 + and 5 / 2 + states, and the origin of these states are discussed.peerReviewe