scholarly journals Sensitivity studies for the weak r process: neutron capture rates

AIP Advances ◽  
2014 ◽  
Vol 4 (4) ◽  
pp. 041008 ◽  
Author(s):  
R. Surman ◽  
M. Mumpower ◽  
R. Sinclair ◽  
K. L. Jones ◽  
W. R. Hix ◽  
...  
Keyword(s):  
Neutron Capture ◽  
Sensitivity Studies ◽  
R Process ◽  
Capture Rates

scholarly journals NEUTRON CAPTURE RATES AND r-PROCESS NUCLEOSYNTHESIS

2013 ◽  
Author(s):  
R. A. SURMAN ◽  
M. R. MUMPOWER ◽  
G. C. MCLAUGHLIN ◽  
R. SINCLAIR ◽  
W. R. HIX ◽  
...  
Keyword(s):  
Neutron Capture ◽  
R Process ◽  
Capture Rates

Neutron capture rates in the r-process - The role of direct radiative capture

1983 ◽  
Vol 270 ◽  
pp. 740 ◽  
Author(s):  
G. J. Mathews ◽  
A. Mengoni ◽  
F.-K. Thielemann ◽  
W. A. Fowler
Keyword(s):  
Neutron Capture ◽  
Radiative Capture ◽  
R Process ◽  
Capture Rates

Reduction of the neutron imaginary potential off the stability line and its possible impact on neutron capture rates

2021 ◽  
Vol 104 (1) ◽  
Author(s):  
A. V. Voinov ◽  
K. Brandenburg ◽  
C. R. Brune ◽  
R. Giri ◽  
S. M. Grimes ◽  
...  
Keyword(s):  
Neutron Capture ◽  
Imaginary Potential ◽  
The Stability ◽  
Capture Rates ◽  
Stability Line

60Fe and 244Pu deposited on Earth constrain the r-process yields of recent nearby supernovae

Science ◽  
2021 ◽  
Vol 372 (6543) ◽  
pp. 742-745
Author(s):  
A. Wallner ◽  
M. B. Froehlich ◽  
M. A. C. Hotchkis ◽  
N. Kinoshita ◽  
M. Paul ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Neutron Stars ◽  
Neutron Capture ◽  
Half Life ◽  
Massive Stars ◽  
Chemical Elements ◽  
Capture Process ◽  
Isotopic Signatures ◽  
Supernova Explosions ◽  
R Process

Half of the chemical elements heavier than iron are produced by the rapid neutron capture process (r-process). The sites and yields of this process are disputed, with candidates including some types of supernovae (SNe) and mergers of neutron stars. We search for two isotopic signatures in a sample of Pacific Ocean crust—iron-60 (60Fe) (half-life, 2.6 million years), which is predominantly produced in massive stars and ejected in supernova explosions, and plutonium-244 (244Pu) (half-life, 80.6 million years), which is produced solely in r-process events. We detect two distinct influxes of 60Fe to Earth in the last 10 million years and accompanying lower quantities of 244Pu. The 244Pu/60Fe influx ratios are similar for both events. The 244Pu influx is lower than expected if SNe dominate r-process nucleosynthesis, which implies some contribution from other sources.

scholarly journals Constraining nucleosynthesis in two CEMP progenitors using fluorine

2020 ◽  
Vol 498 (3) ◽  
pp. 3549-3559
Author(s):  
Aldo Mura-Guzmán ◽  
D Yong ◽  
C Abate ◽  
A Karakas ◽  
C Kobayashi ◽  
...  
Keyword(s):  
Neutron Capture ◽  
Slow Neutron ◽  
Asymptotic Giant Branch ◽  
Capture Process ◽  
Upper Limit ◽  
Infrared Spectrometer ◽  
Binary Evolution ◽  
Vibration Rotation ◽  
R Process ◽  
Process Elements

ABSTRACT We present new fluorine abundance estimations in two carbon enhanced metal-poor (CEMP) stars, HE 1429−0551 and HE 1305+0007. HE 1429−0551 is also enriched in slow neutron-capture process (s-process) elements, a CEMP-s, and HE 1305+0007 is enhanced in both, slow and rapid neutron-capture process elements, a CEMP-s/r. The F abundances estimates are derived from the vibration–rotation transition of the HF molecule at 23358.6 Å  using high-resolution infrared spectra obtained with the Immersion Grating Infrared Spectrometer (IGRINS) at the 4-m class Lowell Discovery Telescope. Our results include an F abundance measurement in HE 1429−0551 of A(F) = +3.93 ([F/Fe] = +1.90) at [Fe/H] = −2.53, and an F upper limit in HE 1305+0007 of A(F) < +3.28 ([F/Fe] < +1.00) at [Fe/H] = −2.28. Our new derived F abundance in HE 1429−0551 makes this object the most metal-poor star where F has been detected. We carefully compare these results with literature values and state-of-the-art CEMP-s model predictions including detailed asymptotic giant branch (AGB) nucleosynthesis and binary evolution. The modelled fluorine abundance for HE 1429−0551 is within reasonable agreement with our observed abundance, although is slightly higher than our observed value. For HE 1429−0551, our findings support the scenario via mass transfer by a primary companion during its thermally pulsing phase. Our estimated upper limit in HE 1305+0007, along with data from the literature, shows large discrepancies compared with AGB models. The discrepancy is principally due to the simultaneous s- and r-process element enhancements which the model struggles to reproduce.

scholarly journals The contribution from rotating massive stars to the enrichment in Sr and Ba of the Milky Way

2019 ◽  
Author(s):  
F Rizzuti ◽  
G Cescutti ◽  
F Matteucci ◽  
A Chieffi ◽  
R Hirschi ◽  
...  
Keyword(s):  
Neutron Capture ◽  
Milky Way ◽  
Massive Stars ◽  
Rotational Velocity ◽  
Stellar Rotation ◽  
Deep Impact ◽  
Low Metallicity ◽  
Group Rotation ◽  
R Process ◽  
Chemical Evolution Model

Abstract Most neutron capture elements have a double production by r- and s-processes, but the question of production sites is complex and still open. Recent studies show that including stellar rotation can have a deep impact on nucleosynthesis. We studied the evolution of Sr and Ba in the Milky Way. A chemical evolution model was employed to reproduce the Galactic enrichment. We tested two different nucleosynthesis prescriptions for s-process in massive stars, adopted from the Geneva group and the Rome group. Rotation was taken into account, studying the effects of stars without rotation or rotating with different velocities. We also tested different production sites for the r-process: magneto rotational driven supernovae and neutron star mergers. The evolution of the abundances of Sr and Ba is well reproduced. The comparison with the the most recent observations shows that stellar rotation is a good assumption, but excessive velocities result in overproduction of these elements. In particular, the predicted evolution of the [Sr/Ba] ratio at low metallicity does not explain the data at best if rotation is not included. Adopting different rotational velocities for different stellar mass and metallicity better explains the observed trends. Despite the differences between the two sets of adopted stellar models, both show a better agreement with the data assuming an increase of rotational velocity toward low metallicity. Assuming different r-process sources does not alter this conclusion.

scholarly journals Measuring neutron capture rates on ILL-produced unstable isotopes (147Pm, 171Tm and 204Tl, and plans for 79Se and 163Ho) for nucleosynthesis studies

2018 ◽  
Vol 193 ◽  
pp. 04007
Author(s):  
J. Lerendegui-Marco ◽  
C. Guerrero ◽  
C. Domingo-Pardo ◽  
A. Casanovas ◽  
R. Dressler ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Cross Sections ◽  
Neutron Capture ◽  
Research Reactor ◽  
Capture Cross ◽  
Preliminary Results ◽  
The Future ◽  
Capture Rates ◽  
Future Plans ◽  
Capture Cross Sections

Neutron capture cross sections are among the main inputs for nucleosynthesis network calculations. Although well known for the majority of the stable isotopes, this quantity is still unknown for most of the unstable isotopes of interest. A recent collaboration between ILL, PSI, U. Sevilla and IFIC aims at producing the isotopes of interest at ILL, preparing suitable targets at PSI, and measuring their capture cross sections at facilities such as n_TOF/CERN, LiLiT and the Budapest Research Reactor (BRR). This work is focused on the description of the different beams and techniques and shows some highlights of the preliminary results of the capture measurements on 171Tm, 147Pm and 204Tl, along with the future plans for 79Se and 163Ho.

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