Search results for "nuclear experiment"
showing 10 items of 7971 documents
Discovery of the new isotopes ²⁴⁰Es and ²³⁶Bk and in-beam spectroscopic studies of ²⁴⁴Cf
2017
The hitherto unknown neutron-deficient nuclei 240Es and 236Bk were synthesised using the fusion-evaporation reaction 209Bi(34S,3n)240Es. The ritu gas-filled recoil separator and the great spectrometer were used in this decay spectroscopic study. The measured electron-capture delayed fission (ECDF) branches in both of the new isotopes complement the experimental data available in the heavier odd-odd Es and Bk isotopes. Furthermore, the ECDF branches show a continuation in the exponential increase of the ECDF probabilities as a function of QEC − Bsf when approaching the proton dripline. In addition, an in-beam γ-ray spectroscopic study of the neutron-deficient isotope 244Cf was made using the fus…
First β-decay spectroscopy of $^{135}$In and new $β$-decay branches of $^{134}$In
2021
International audience; The $\beta$ decay of the neutron-rich $^{134}$In and $^{135}$In was investigated experimentally in order to provide new insights into the nuclear structure of the tin isotopes with magic proton number $Z=50$ above the $N=82$ shell. The $\beta$-delayed $\gamma$-ray spectroscopy measurement was performed at the ISOLDE facility at CERN, where indium isotopes were selectively laser-ionized and on-line mass separated. Three $\beta$-decay branches of $^{134}$In were established, two of which were observed for the first time. Population of neutron-unbound states decaying via $\gamma$ rays was identified in the two daughter nuclei of $^{134}$In, $^{134}$Sn and $^{133}$Sn, at…
Excited levels in the multishaped 117Pd nucleus studied via β decay of 117Rh
2018
Monoisotopic samples of exotic, neutron-rich 117Rh nuclei, produced in the proton-induced fission of 238U and separated using the IGISOL mass separator coupled to the JYFLTRAP Penning trap, were used to perform β and γ coincidence spectroscopy of 117Pd. The spin parity of the ground state of 117Pd was determined to be 1/2+ and the 19.1 ms isomer at 203.2 keV was assigned a spin-parity 7/2−. The 117Rh β−-decay scheme was considerably extended, and various sequences of the levels were interpreted as resulting from the prolate, oblate, and triaxial nuclear shapes. Some of the β− decays were considered as the allowed Gamow-Teller transitions. The experimental distribution of Gamow-Teller streng…
High-resolution laser spectroscopy of $^{27-32}$Al
2020
Physical review / C 103(1), 014318 (2021). doi:10.1103/PhysRevC.103.014318
γ decay of excited states in 198Rn identified using correlated radioactive decay
1999
The low-lying level structure of the neutron-deficient isotope 198Rn has been studied for the first time, using the 166Er(36Ar,4n) reaction at a beam energy of 175 MeV. Evaporation residues were selected using an in-flight gas-filled separator, RITU, and implanted at the focal plane into a 16-element position-sensitive, passivated ion-implanted planar silicon detector. Prompt γ rays in 198Rn were observed at the target position using the JUROSPHERE array of 24 Compton-suppressed germanium detectors, and were identified by the subsequent radioactive decay of associated recoiling ions in the silicon detector. Isotopic assignments of the nuclei produced were made on the basis of the energy and…
Centrality-Dependent Modification of Jet-Production Rates in Deuteron-Gold Collisions at √sNN = 200 GeV
2016
Jet production rates are measured in p þ p and d þ Au collisions at √sNN = 200 GeV recorded in 2008 with the PHENIX detector at the Relativistic Heavy Ion Collider. Jets are reconstructed using the R ¼ 0.3 anti-kt algorithm from energy deposits in the electromagnetic calorimeter and charged tracks in multiwire proportional chambers, and the jet transverse momentum (pT ) spectra are corrected for the detector response. Spectra are reported for jets with 12 < pT < 50 GeV=c, within a pseudorapidity acceptance of jηj < 0.3. The nuclear-modification factor (RdAu) values for 0%–100% d þ Au events are found to be consistent with unity, constraining the role of initial state effects on jet product…
Extracting qˆ in event-by-event hydrodynamics and the centrality/energy puzzle
2017
In our analysis, we combine event-by-event hydrodynamics, within the EKRT formulation, with jet quenching -ASW Quenching Weights- to obtain high- for charged particles at RHIC and LHC energies for different centralities. By defining a K-factor that quantifies the departure of from an ideal estimate, , we fit the single-inclusive experimental data for charged particles. This K-factor is larger at RHIC than at the LHC but, surprisingly, it is almost independent of the centrality of the collision. peerReviewed
Exploration of jet substructure using iterative declustering in pp and Pb–Pb collisions at LHC energies
2020
The ALICE collaboration at the CERN LHC reports novel measurements of jet substructure in pp collisions at $\sqrt{s}$= 7 TeV and central Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 2.76 TeV. Jet substructure of track-based jets is explored via iterative declustering and grooming techniques. We present the measurement of the momentum sharing of two-prong substructure exposed via grooming, the $z_{\rm{g}}$, and its dependence on the opening angle, in both pp and Pb-Pb collisions. We also present the first measurement of the distribution of the number of branches obtained in the iterative declustering of the jet, which is interpreted as the number of its hard splittings. In Pb-Pb collisions, we…
Uncertainties on the determination of the strong coupling αs from the energy evolution of jet fragmentation functions at low z
2014
The QCD coupling alpha_s is determined at NLO*+NMLLA accuracy from the comparison of experimental jet data to theoretical predictions of the energy-evolution of the parton-to-hadron fragmentation function moments (multiplicity, peak, width, skewness) at low fractional hadron momentum z. From the existing e+e- and e-p jet data, we obtain alpha_s(m_Z^2) = 0.1195 +/- 0.0021 (exp.) {+0.0015}_{-0.0} (scale) at the Z mass. The uncertainties of the extracted alpha_s value are discussed.
Dijet studies with ALICE at the LHC
2020
Relativistisissa hiukkastörmäyksissä syntyvistä suurenergisistä kvarkeista ja gluoneista, eli partoneista, muodostuvaa hyvin kollimoitunutta hiukkassuihkua kutsutaan jetiksi. Jettien tutkimusta on tehty jo vuosikaudet ja se hallitaan hyvin myös raskasionitörmäyksissä, joissa muodostuvaa kvarkkigluoniplasmaa on pystytty tutkimaan jettien liikemäärähäviöiden avulla. Tämän perusteella on huomattu, että kvarkkigluoniplasma jarruttaa sen läpi kulkevia suurenergisiä partoneita. Jettien lisäksi partonien energiahäviöitä raskasionitörmäyksessä on tutkittu myös dijettien avulla. Dijetti on määritelty törmäyksen kahdesta suurimman energian omaavasta jetistä muodostuvaksi systeemiksi. Aiempien RHIC- j…