Title: 40 Ar proposed as probe of neutron-induced reactions in a high-density stellar-like plasma at the National Ignition Facility
The thermodynamical conditions and the neutron density produced in a laser-induced implosion of a deuterium-tritium (DT) filled capsule at the National Ignition Facility (NIF) are the closest laboratory analog of stellar conditions. We plan to investigate neutron-induced reactions on 40 Ar, namely the 40 Ar( n , 2 n ) 39 Ar( t 1/2 =268 y), the 40 Ar( n , γ) 41 Ar(110 min) and the potential rapid two-neutron capture reaction 40 Ar(2 n , γ) 42 Ar(33 y) in an Ar-loaded DT capsule. The chemical inertness of noble gas Ar enables reliable collection of the reaction products. more »« less
Sahoo, R. N.; Paul, M.; Köster, U.; Scott, R.; Tessler, M.; Zylstra, A.; Avila, M. L.; Dickerson, C.; Jayatissa, H.; Kohen, M.S.; et al(
, EPJ Web of Conferences)
Mattoon, C.M.; Vogt, R.; Escher, J.; Thompson, I.
(Ed.)
The cross-section of the thermal neutron capture41Ar(n,γ)42Ar(t1/2=32.9 y) reaction was measured by irradiating a40Ar sample at the high-flux reactor of Institut Laue-Langevin (ILL) Grenoble, France. The signature of the two-neutron capture has been observed by measuring the growth curve and identifying the 1524.6 keV γ-lines of the shorter-lived42K(12.4 h) β−daughter of42Ar. Our preliminary value of the41Ar(n,γ)42Ar thermal cross section is 240(80) mb at 25.3 meV. For the first time, direct counting of42Ar was performed using the ultra-high sensitivity technique of noble gas accelerator mass spectrometry (NOGAMS) at Argonne National Laboratory, USA.
Tsintari, Pelagia; Berg, Georg P.; Blackmon, Jeff; Chipps, Kelly; Couder, Manoel; Deibel, Catherine; Dimitrakopoulos, Nikolaos; Garg, Ruchi; Greife, Uwe; Hermansen, Kirby; et al(
, EPJ Web of Conferences)
Freeman, S.; Lederer-Woods, C.; Manna, A.; Mengoni, A.
(Ed.)
The formation of nuclei in slightly proton-rich regions of the neutrino-driven wind of core-collapse supernovae could be attributed to the neutrino-p process (νp-process). As it proceeds via a sequence of (p,γ) and (n,p) reactions, it may produce elements in the range of Ni and Sn, considering adequate conditions. Recent studies identify a number of decisive (n,p) reactions that control the efficiency of the νp-process. The study of one such (n,p) reaction via the measurement of the reverse (p,n) in inverse kinematics was performed with SECAR at NSCL/FRIB. Proton-induced reaction measurements, especially at the mass region of interest, are notably difficult since the recoils have nearly identical masses as the unreacted projectiles. Such measurements are feasible with the adequate separation level achieved with SECAR, and the in-coincidence neutron detection. Adjustments of the SECAR system for the first (p,n) reaction measurement included the development of new ion beam optics, and the installation of the neutron detection system. The aforementioned developments along with a discussion on the preliminary results of the p( 58 Fe,n) 58 Co reaction measurement are presented.
Nucleosynthesis in the ν p-process occurs in regions of slightly proton-rich nuclei in the neutrino-driven wind of core-collapse supernovae. The process proceeds via a sequence of (p, γ ) and (n,p) reactions, and depending on the conditions, may produce elements between Ni and Sn. Recent studies show that a few key (n,p) reactions regulate the efficiency of the neutrino-p process ( ν p-process). We performed a study of one of such (n,p) reactions via the measurement of the reverse (p,n) in inverse kinematics with SECAR at NSCL/FRIB.Such proton-induced reaction measurements are particularly challenging, as the recoils and the unreacted projectiles have nearly identical masses. An appropriate separation level can be achieved with SECAR, and along with the incoincidence detection of neutrons these measurements become attainable. The preparation of the SECAR system for accommodating its first (p,n) reaction measurement, including the development of alternative ion beam optics, and the setup of the in-coincidence neutron detection, along with discussion on preliminary results from the p( 58 Fe,n) 58 Co reaction measurement are presented and discussed.
Ryan, Austin J.; Ziller, Joseph W.; Evans, William J.(
, Chemical Science)
The use of 18-crown-6 (18-c-6) in place of 2.2.2-cryptand (crypt) in rare earth amide reduction reactions involving potassium has proven to be crucial in the synthesis of Ln( ii ) complexes and isolation of their CO reduction products. The faster speed of crystallization with 18-c-6 appears to be important. Previous studies have shown that reduction of the trivalent amide complexes Ln(NR 2 ) 3 (R = SiMe 3 ) with potassium in the presence of 2.2.2-cryptand (crypt) forms the divalent [K(crypt)][Ln II (NR 2 ) 3 ] complexes for Ln = Gd, Tb, Dy, and Tm. However, for Ho and Er, the [Ln(NR 2 ) 3 ] 1− anions were only isolable with [Rb(crypt)] 1+ counter-cations and isolation of the [Y II (NR 2 ) 3 ] 1− anion was not possible under any of these conditions. We now report that by changing the potassium chelator from crypt to 18-crown-6 (18-c-6), the [Ln(NR 2 ) 3 ] 1− anions can be isolated not only for Ln = Gd, Tb, Dy, and Tm, but also for Ho, Er, and Y. Specifically, these anions are isolated as salts of a 1 : 2 potassium : crown sandwich cation, [K(18-c-6) 2 ] 1+ , i.e. [K(18-c-6) 2 ][Ln(NR 2 ) 3 ]. The [K(18-c-6) 2 ] 1+ counter-cation was superior not only in the synthesis, but it also allowed the isolation of crystallographically-characterizable products from reactions of CO with the [Ln(NR 2 ) 3 ] 1− anions that were not obtainable from the [K(crypt)] 1+ analogs. Reaction of CO with [K(18-c-6) 2 ][Ln(NR 2 ) 3 ], generated in situ , yielded crystals of the ynediolate products, {[(R 2 N) 3 Ln] 2 (μ-OCCO)} 2− , which crystallized with counter-cations possessing 2 : 3 potassium : crown ratios, i.e. {[K 2 (18-c-6) 3 ]} 2+ , for Gd, Dy, Ho. In contrast, reaction of CO with a solution of isolated [K(18-c-6) 2 ][Gd(NR 2 ) 3 ], produced crystals of an enediolate complex isolated with a counter-cation with a 2 : 2 potassium : crown ratio namely [K(18-c-6)] 2 2+ in the complex [K(18-c-6)] 2 {[(R 2 N) 2 Gd 2 (μ-OCHCHO) 2 ]}.
In Type-I X-ray bursts (XRBs), the rapid-proton capture (rp-) process passes through the NiCu and ZnGa cycles before reaching the region above Ge and Se isotopes that hydrogen burning actively powers the XRBs. The sensitivity study performed by Cyburt et al . [1] shows that the 57 Cu(p, γ ) 58 Zn reaction in the NiCu cycles is the fifth most important rp-reaction influencing the burst light curves. Langer et al . [2] precisely measured some low-lying energy levels of 58 Zn to deduce the 57 Cu(p, γ ) 58 Zn reaction rate. Nevertheless, the order of the 1 + 1 and 2 + 3 resonance states that dominate at 0:2 ≲ T (GK) ≲ 0:8 is not confirmed. The 1 + 2 resonance state, which dominates at the XRB sensitive temperature regime 0:8 ≲ T (GK) ≲ 2 was not detected. Using isobaric-multipletmass equation (IMME), we estimate the order of the 1 + 1 and 2 + 3 resonance states and estimate the lower limit of the 1 + 2 resonance energy. We then determine the 57 Cu(p, γ ) 58 Zn reaction rate using the full pf -model space shell model calculations. The new rate is up to a factor of four lower than the Forstner et al . [3] rate recommended by JINA REACLIBv2.2. Using the present 57 Cu(p, γ ) 58 Zn, the latest 56 Ni(p, γ ) 57 Cu and 55 Ni(p, γ ) 56 Cu reaction rates, and 1D implicit hydrodynamic K epler code, we model the thermonuclear XRBs of the clocked burster GS 1826–24. We find that the new rates regulate the reaction flow in the NiCu cycles and strongly influence the burst-ash composition. The 59 Cu(p, γ ) 56 Ni and 59 Cu(p, α ) 60 Zn reactions suppress the influence of the 57 Cu(p, γ ) 58 Zn reaction. They strongly diminish the impact of the nuclear reaction flow that bypasses the 56 Ni waiting point induced by the 55 Ni(p, γ ) 56 Cu reaction on burst light curve.
Paul, M., Sahoo, R. N., Tessler, M., Jeet, J., Velsko, C., Zylstra, A., Avila, M., Dickerson, C., Fougères, C., Jayatissa, H., Pardo, R. C., Rehm, K. E., Scott, R., Tolstukhin, I., Vondrasek, R., Bailey, T., Callahan, L., Clark, A. M., Collon, P., Kashiv, Y., Nelson, A., Köster, U., Hoffmann, H. F., Pichotta, M., Zuber, K., Döring, T., and Schwengner, R. 40 Ar proposed as probe of neutron-induced reactions in a high-density stellar-like plasma at the National Ignition Facility. Retrieved from https://par.nsf.gov/biblio/10429378. EPJ Web of Conferences 279. Web. doi:10.1051/epjconf/202327913004.
Paul, M., Sahoo, R. N., Tessler, M., Jeet, J., Velsko, C., Zylstra, A., Avila, M., Dickerson, C., Fougères, C., Jayatissa, H., Pardo, R. C., Rehm, K. E., Scott, R., Tolstukhin, I., Vondrasek, R., Bailey, T., Callahan, L., Clark, A. M., Collon, P., Kashiv, Y., Nelson, A., Köster, U., Hoffmann, H. F., Pichotta, M., Zuber, K., Döring, T., & Schwengner, R. 40 Ar proposed as probe of neutron-induced reactions in a high-density stellar-like plasma at the National Ignition Facility. EPJ Web of Conferences, 279 (). Retrieved from https://par.nsf.gov/biblio/10429378. https://doi.org/10.1051/epjconf/202327913004
Paul, M., Sahoo, R. N., Tessler, M., Jeet, J., Velsko, C., Zylstra, A., Avila, M., Dickerson, C., Fougères, C., Jayatissa, H., Pardo, R. C., Rehm, K. E., Scott, R., Tolstukhin, I., Vondrasek, R., Bailey, T., Callahan, L., Clark, A. M., Collon, P., Kashiv, Y., Nelson, A., Köster, U., Hoffmann, H. F., Pichotta, M., Zuber, K., Döring, T., and Schwengner, R.
"40 Ar proposed as probe of neutron-induced reactions in a high-density stellar-like plasma at the National Ignition Facility". EPJ Web of Conferences 279 (). Country unknown/Code not available. https://doi.org/10.1051/epjconf/202327913004.https://par.nsf.gov/biblio/10429378.
@article{osti_10429378,
place = {Country unknown/Code not available},
title = {40 Ar proposed as probe of neutron-induced reactions in a high-density stellar-like plasma at the National Ignition Facility},
url = {https://par.nsf.gov/biblio/10429378},
DOI = {10.1051/epjconf/202327913004},
abstractNote = {The thermodynamical conditions and the neutron density produced in a laser-induced implosion of a deuterium-tritium (DT) filled capsule at the National Ignition Facility (NIF) are the closest laboratory analog of stellar conditions. We plan to investigate neutron-induced reactions on 40 Ar, namely the 40 Ar( n , 2 n ) 39 Ar( t 1/2 =268 y), the 40 Ar( n , γ) 41 Ar(110 min) and the potential rapid two-neutron capture reaction 40 Ar(2 n , γ) 42 Ar(33 y) in an Ar-loaded DT capsule. The chemical inertness of noble gas Ar enables reliable collection of the reaction products.},
journal = {EPJ Web of Conferences},
volume = {279},
author = {Paul, M. and Sahoo, R. N. and Tessler, M. and Jeet, J. and Velsko, C. and Zylstra, A. and Avila, M. and Dickerson, C. and Fougères, C. and Jayatissa, H. and Pardo, R. C. and Rehm, K. E. and Scott, R. and Tolstukhin, I. and Vondrasek, R. and Bailey, T. and Callahan, L. and Clark, A. M. and Collon, P. and Kashiv, Y. and Nelson, A. and Köster, U. and Hoffmann, H. F. and Pichotta, M. and Zuber, K. and Döring, T. and Schwengner, R.},
editor = {Freeman, S. and Lederer-Woods, C. and Manna, A. and Mengoni, A.}
}
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