Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userAlpha-decay-correlated mass measurement of 206,207Ra using an {alpha}-TOF detector equipped MRTOF-MS system
167
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
The atomic masses of the isotopes 206,207Ra have been measured via decay-correlated mass spectroscopy using a multi-reflection time-of-flight mass spectrograph equipped with an {alpha}-TOF detector. The Ra isotopes were produced as fusion-evaporation products in the 51V+159Tb reaction system and delivered by the gas-filled recoil ion separator GARIS-II at RIKEN. The {alpha}-TOF detector provides for high-accuracy mass measurements by correlating time-of-flight signals with subsequent {alpha}-decay events. The masses of 207gRa and 207mRa were directly measured using a multi-reflection time-of-flight mass spectrograph equipped with an {alpha}-TOF detector. A mass excess of ME = 3538(15) keV/c2 and an excitation energy of Eex = 552(42) keV were determined. The {alpha}-decay branching ratio of 207mRa, b{alpha} = 0.26(20), was directly determined from decay-correlated time-of- flight signals, and the reduced alpha width of 207mRa was calculated to be {delta}2 = 50+62-41 keV from the branching ratio. The spin-parity of 207mRa was confirmed to be J{pi} = 13/2 from decay correlated mass measurement results.
rate research
Read More
We have developed a novel detector, referred to as an $alpha$-ToF detector, for correlated measurements of atomic masses and decay properties of low-yield, short-lived radioactive isotopes using a multi-reflection time-of-flight mass spectrograph. By correlating measured time-of-flight signals with decay events, it will be possible to suppress background events and obtain accurate, high-precision mass values even in cases of very low event rates. An offline test of the $alpha$-ToF detector has shown that the time-of-flight detection efficiency for 5.48~MeV $alpha$-rays is more than 90% and yields a time resolution of 251.5(68)~ps and an energy resolution of 141.1(9)~keV. Using a two-dimensional spectrum of the correlated $alpha$-ray energy and time-of-flight, the $alpha$-rays from mixed $alpha$ sources could be fairly well resolved.
We propose a new method of alpha($alpha$)-ray measurement that detects helium atoms with a Quadrupole Mass Spectrometer(QMS). A demonstration is undertaken with a plastic-covered $^{241}$Am $alpha$-emitting source to detect $alpha$-rays stopped in the capsule. We successfully detect helium atoms that diffuse out of the capsule by accumulating them for one to 20 hours in a closed chamber. The detected amount is found to be proportional to the accumulation time. Our method is applicable to probe $alpha$-emitting radioactivity in bulk material.
A new search for production of correlated e+e- pairs in the alpha decay of 241Am has been carried out deep underground at the Gran Sasso National Laboratory of the I.N.F.N. by using pairs of NaI(Tl) detectors of the DAMA/LIBRA set-up. The experimental data show an excess of double coincidences of events with energy around 511 keV in faced pairs of detectors, which are not explained by known side reactions. This measured excess gives a relative activity lambda = (4.70 pm 0.63) times 10^{-9} for the Internal Pair Production (IPP) with respect to alpha decay of 241Am; this value is of the same order of magnitude as previous determinations. In a conservative approach the upper limit lambda < 5.5 times 10^{-9} (90% C.L.) can be derived. It is worth noting that this is the first result on IPP obtained in an underground experiment, and that the lambda value obtained in the present work is independent on the live-time estimate.
While the 12C(a,g)16O reaction plays a central role in nuclear astrophysics, the cross section at energies relevant to hydrostatic helium burning is too small to be directly measured in the laboratory. The beta-delayed alpha spectrum of 16N can be used to constrain the extrapolation of the E1 component of the S-factor; however, with this approach the resulting S-factor becomes strongly correlated with the assumed beta-alpha branching ratio. We have remeasured the beta-alpha branching ratio by implanting 16N ions in a segmented Si detector and counting the number of beta-alpha decays relative to the number of implantations. Our result, 1.49(5)e-5, represents a 24% increase compared to the accepted value and implies an increase of 14% in the extrapolated S-factor.
The decay properties of the ground state and excited states of $^{257}$Rf have been investigated with the detector array GABRIELA at the FLNR, Dubna. The electromagnetic decay of a new excited state in $^{253}$No has been observed. The state lies 750 keV above the ground state and is favourably populated in the alpha decay of the low-lying spin isomer of $^{257}$Rf. It decays to the 9/2$^-$ ground state by an M1 transition and is assigned the 11/2$^-$[725] Nilsson configuration. The presence of this state suggests a possible reinterpretation of the decay of the high-K isomer in $^{253}$No.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
