555 research outputs found
Nanoelectronic thermometers optimised for sub-10 millikelvin operation
We report the cooling of electrons in nanoelectronic Coulomb blockade
thermometers below 4 mK. Above 7 mK the devices are in good thermal contact
with the environment, well isolated from electrical noise, and not susceptible
to self-heating. This is attributed to an optimised design that incorporates
cooling fins with a high electron-phonon coupling and on-chip electronic
filters, combined with a low-noise electronic measurement setup. Below 7 mK the
electron temperature is seen to diverge from the ambient temperature. By
immersing a Coulomb Blockade Thermometer in the 3He/4He refrigerant of a
dilution refrigerator, we measure a lowest electron temperature of 3.7 mK.Comment: 11 pages, 4 figures. (Fixed fitted saturation T_e on p9
Isomeric states close to doubly magic Sn studied with JYFLTRAP
The double Penning trap mass spectrometer JYFLTRAP has been employed to
measure masses and excitation energies for isomers in Cd,
Cd, Cd and Te, for isomers in In and
In, and for isomers in Sn and Sb. These first
direct mass measurements of the Cd and In isomers reveal deviations to the
excitation energies based on results from beta-decay experiments and yield new
information on neutron- and proton-hole states close to Sn. A new
excitation energy of 144(4) keV has been determined for Cd. A good
agreement with the precisely known excitation energies of Cd,
Sn, and Sb has been found.Comment: 10 pages, 6 figures, submitted to Phys. Rev.
Q_EC values of the Superallowed beta-Emitters 10-C, 34-Ar, 38-Ca and 46-V
The Q_EC values of the superallowed beta+ emitters 10-C, 34-Ar, 38-Ca and
46-V have been measured with a Penning-trap mass spectrometer to be 3648.12(8),
6061.83(8), 6612.12(7) and 7052.44(10) keV, respectively. All four values are
substantially improved in precision over previous results.Comment: 9 pages, 7 figures, 5 table
Precision mass measurements on neutron-rich rare-earth isotopes at JYFLTRAP - reduced neutron pairing and implications for the -process calculations
The rare-earth peak in the -process abundance pattern depends sensitively
on both the astrophysical conditions and subtle changes in nuclear structure in
the region. This work takes an important step elucidating the nuclear structure
and reducing the uncertainties in -process calculations via precise atomic
mass measurements at the JYFLTRAP double Penning trap. Nd, Pm,
Sm, and Gd have been measured for the first time and the
precisions for Nd, Pm, Eu, Gd, and
Tb have been improved considerably. Nuclear structure has been probed
via two-neutron separation energies and neutron pairing energy metrics
. The data do not support the existence of a subshell closure at .
Neutron pairing has been found to be weaker than predicted by theoretical mass
models. The impact on the calculated -process abundances has been studied.
Substantial changes resulting in a smoother abundance distribution and a better
agreement with the solar -process abundances are observed.Comment: 8 pages, 4 figures, accepted for publication in Physical Review
Letter
Measurement of parity-nonconserving rotation of neutron spin in the 0.734-eV p-wave resonance of
The parity nonconserving spin rotation of neutrons in the 0.734-eV p-wave
resonance of was measured with the neutron transmission method. Two
optically polarized cells were used before and behind a a 5-cm long
target as a polarizer and an analyzer of neutron spin. The rotation
angle was carefully measured by flipping the direction of polarization
in the polarizer in sequence. The peak-to-peak value of the spin rotation was
found to be rad/cm which was consistent with
the previous experiments. But the result was statisticallly improved. The s-p
mixing model gives the weak matrix element as meV. The
value agrees well with the one deduced from the parity-nonconserving
longitudinal asymmetry in the same resonance
Asteroid observations at low phase angles. IV : Average parameters for the new H, G1, G2 magnitude system
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