307 research outputs found
High-energy sub-nanosecond optical pulse generation with a semiconductor laser diode for pulsed TOF laser ranging utilizing the single photon detection approach
Bulk and quantum well laser diodes with a large equivalent spot size of da/Îa â 3 ”m and stripe width/cavity length of 30 ”m/3 mm were realized and tested. They achieved a pulse energy and pulse length of the order of ~1 nJ and ~100 ps, respectively, with a peak pulse current of 6â8 A and a current pulse width of 1 ns. The 2D characteristics of the optical output power versus wavelength and time were also analyzed with a monochromator/streak camera set-up. The far-field characteristics were studied with respect to the time-homogeneity and energy distribution. The feasibility of a laser diode with a large equivalent spot size in single photon detection based laser ranging was demonstrated to a non-cooperative target at a distance of a few tens of meters
Decay of [Formula Presented] to [Formula Presented]
The decay of on-line mass-separated [Formula Presented] has been studied by [Formula Presented] spectroscopy. A definite odd parity and a probable [Formula Presented] are deduced for the high-spin [Formula Presented]-decaying level. The 1116 keV and 1392 keV levels in the [Formula Presented] daughter nucleus are candidates for the bottom of the [Formula Presented] band. There is no support for a previously reported very-low-lying [Formula Presented] level at 871 keV. A [Formula Presented] band built on the new level at 1639 keV is proposed. The lowest-lying two-quasiparticle levels in [Formula Presented] are calculated in the framework of the quantum Monte Carlo pairing model using deformed shell model states. The lowest configurations are associated with an oblate minimum of the potential energy.</p
First direct observation of two protons in the decay of Fe with a TPC
The decay of the ground-state two-proton emitter 45Fe was studied with a
time-projection chamber and the emission of two protons was unambiguously
identified. The total decay energy and the half-life measured in this work
agree with the results from previous experiments. The present result
constitutes the first direct observation of the individual protons in the
two-proton decay of a long-lived ground-state emitter. In parallel, we
identified for the first time directly two-proton emission from 43Cr, a known
beta-delayed two-proton emitter. The technique developped in the present work
opens the way to a detailed study of the mechanism of ground-state as well as
beta-delayed two-proton radioactivity.Comment: 4 pages, 5 figure
Precision measurement of the half-life and the decay branches of 62Ga
In an experiment performed at the Accelerator Laboratory of the University of
Jyvaskyla, the beta-decay half-life of 62Ga has been studied with high
precision using the IGISOL technique. A half-life of T1/2 = 116.09(17)ms was
measured. Using beta-gamma coincidences, the gamma intensity of the 954keV
transition and an upper limit of the beta-decay feeding of the 0+_2 state have
been extracted. The present experimental results are compared to previous
measurements and their impact on our understanding of the weak interaction is
discussed.Comment: 7 pages, 7 figures, submitted to EPJ
Ground-state spin of Mn
Beta decay of Mn has been studied at PSB-ISOLDE, CERN. The intense and pure Mn beam was produced using the Resonance Ionization Laser Ion Source (RILIS). Based on the measured -decay rates the ground-state spin and parity are proposed to be = 5/2. This result is consistent with the systematic trend of the odd-A Mn nuclei and extends the systematics one step further towards the neutron drip line
Off-line studies of the laser ionization of yttrium at the IGISOL facility
A laser ion source is under development at the IGISOL facility, Jyvaskyla, in
order to address deficiencies in the ion guide technique. The key elements of
interest are those of a refractory nature, whose isotopes and isomers are
widely studied using both laser spectroscopic and high precision mass
measurement techniques. Yttrium has been the first element of choice for the
new laser ion source. In this work we present a new coupled dye-Ti:Sapphire
laser scheme and give a detailed discussion of the results obtained from laser
ionization of yttrium atoms produced in an ion guide via joule heating of a
filament. The importance of not only gas purity, but indeed the baseline vacuum
pressure in the environment outside the ion guide is discussed in light of the
fast gas phase chemistry seen in the yttrium system. A single laser shot model
is introduced and is compared to the experimental data in order to extract the
level of impurities within the gas cell.Comment: 18 pages submitted to NIM
Collinear laser spectroscopy of radioisotopes of zirconium
Isotope shifts and hyperfine structures have been measured for radioisotopes of ionic zirconium using on-line laser spectroscopy at the IGISOL facility in JyvÀskylÀ, where the installation of an ion beam cooler/buncher has significantly improved the experimental sensitivity. Measurements have been made on all the neutron-deficient isotopes from 87Zr to 90Zr, including the isomers 87m,89mZr, and the neutron-rich isotopes from 96Zr to 102Zr. The change in mean square charge radii between the isotopes and the nuclear moments of the odd isotopes have been extracted. The data show a sudden increase in the mean square charge radius at mass A = 100, consistent with an onset of nuclear deformation which has been observed in the gamma ray spectroscopy of isotope chains in this region of the nuclear chart.</p
[Formula Presented] decay of neutron-rich [Formula Presented] and [Formula Presented] isotopes
[Formula Presented] decays of on-line mass-separated neutron-rich [Formula Presented] and [Formula Presented] isotopes have been studied by using [Formula Presented] and [Formula Presented] coincidence spectroscopy. Extended decay schemes to the [Formula Presented] daughter nuclei have been constructed. The three-phonon quintuplet in [Formula Presented] is completed by including a new level at 2023.0 keV, which is tentatively assigned the spin and parity of [Formula Presented] The intruder band in [Formula Presented] is proposed up to the [Formula Presented] level at 2322.4 keV. The measured [Formula Presented]-decay half-life for the high-spin isomer of [Formula Presented] is [Formula Presented] Candidates for the three-phonon states, as well as the lowest members of the intruder band in [Formula Presented] are also presented. These data support the coexistence of quadrupole anharmonic vibration and proton particle-hole intruder excitations in [Formula Presented].</p
Q-value of the superallowed beta decay of Ga-62
Masses of the radioactive isotopes 62Ga, 62Zn and 62Cu have been measured at
the JYFLTRAP facility with a relative precision of better than 18 ppb. A Q_EC
value of (9181.07 +- 0.54) keV for the superallowed decay of 62Ga is obtained
from the measured cyclotron frequency ratios of 62Ga-62Zn, 62Ga-62Ni and
62Zn-62Ni ions. The resulting Ft-value supports the validity of the conserved
vector current hypothesis (CVC). The mass excess values measured were (-51986.5
+-1.0) keV for 62Ga, (-61167.9 +- 0.9) keV for 62Zn and (-62787.2 +- 0.9) keV
for 62Cu.Comment: 12 pages, 3 figures, 2 tables, submitted to Phys. Lett. B. v2: added
acknowledgement
A new isomer in La
Levels in La have been studied via /EC decay of on-line
mass-separated Ce using the HIGISOL technique. A new (390 40) ms isomer
is definitely attributed to La by conversion electron measurements of the 107 keV E3
isomeric transition
- âŠ