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51. Design and Construction of a Gas Jet Target for RIB Experiements

Author

Greife, Uwe, primary, Chipps, Kelly A., additional, Smith, Michael, additional, Bardayan, Dan W., additional, Pain, Steven D., additional, Schmitt, Kyle, additional, Schatz, Hendrik, additional, Montes, Fernando, additional, Blackmon, Jeff, additional, Wiescher, Michael, additional, Couder, Manoel, additional, Vetter, Paul, additional, Lemut, Alberto, additional, and Erikson, Luke E., additional

Published
2011
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52. The impact of (n,γ) reaction rate uncertainties on the predicted abundances of i-process elements with 32 ≤ Z ≤ 48 in the metal-poor star HD94028.

Author

McKay, John E, Denissenkov, Pavel A, Herwig, Falk, Perdikakis, Georgios, and Schatz, Hendrik

Subjects
MONTE Carlo method, INTEGRAL field spectroscopy, PEARSON correlation (Statistics), NUCLEAR physics, NUCLEOSYNTHESIS, NUCLEAR reactions
Abstract

Several anomalous elemental abundance ratios have been observed in the metal-poor star HD94028. We assume that its high [As/Ge] ratio is a product of a weak intermediate (i) neutron-capture process. Given that observational errors are usually smaller than predicted nuclear physics uncertainties, we have first set-up a benchmark one-zone i-process nucleosynthesis simulation results of which provide the best fit to the observed abundances. We have then performed Monte Carlo simulations in which 113 relevant (n,γ) reaction rates of unstable species were randomly varied within Hauser–Feshbach model uncertainty ranges for each reaction to estimate the impact on the predicted stellar abundances. One of the interesting results of these simulations is a double-peaked distribution of the As abundance, which is caused by the variation of the 75Ga (n,γ) cross-section. This variation strongly anticorrelates with the predicted As abundance, confirming the necessity for improved theoretical or experimental bounds on this cross-section. The 66Ni (n,γ) reaction is found to behave as a major bottleneck for the i-process nucleosynthesis. Our analysis finds the Pearson product–moment correlation coefficient r P > 0.2 for all of the i-process elements with 32 ≤ Z ≤ 42, with significant changes in their predicted abundances showing up when the rate of this reaction is reduced to its theoretically constrained lower bound. Our results are applicable to any other stellar nucleosynthesis site with the similar i-process conditions, such as Sakurai's object (V4334 Sagittarii) or rapidly accreting white dwarfs. [ABSTRACT FROM AUTHOR]

Published
2020
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53. Dense matter with eXTP

Author

Watts, Anna L., primary, Yu, WenFei, additional, Poutanen, Juri, additional, Zhang, Shu, additional, Bhattacharyya, Sudip, additional, Bogdanov, Slavko, additional, Ji, Long, additional, Patruno, Alessandro, additional, Riley, Thomas E., additional, Bakala, Pavel, additional, Baykal, Altan, additional, Bernardini, Federico, additional, Bombaci, Ignazio, additional, Brown, Edward, additional, Cavecchi, Yuri, additional, Chakrabarty, Deepto, additional, Chenevez, Jérôme, additional, Degenaar, Nathalie, additional, Del Santo, Melania, additional, Di Salvo, Tiziana, additional, Doroshenko, Victor, additional, Falanga, Maurizio, additional, Ferdman, Robert D., additional, Feroci, Marco, additional, Gambino, Angelo F., additional, Ge, MingYu, additional, Greif, Svenja K., additional, Guillot, Sebastien, additional, Gungor, Can, additional, Hartmann, Dieter H., additional, Hebeler, Kai, additional, Heger, Alexander, additional, Homan, Jeroen, additional, Iaria, Rosario, additional, Zand, Jean in’t, additional, Kargaltsev, Oleg, additional, Kurkela, Aleksi, additional, Lai, XiaoYu, additional, Li, Ang, additional, Li, XiangDong, additional, Li, ZhaoSheng, additional, Linares, Manuel, additional, Lu, FangJun, additional, Mahmoodifar, Simin, additional, Méndez, Mariano, additional, Coleman Miller, M., additional, Morsink, Sharon, additional, Nättilä, Joonas, additional, Possenti, Andrea, additional, Prescod-Weinstein, Chanda, additional, Qu, JinLu, additional, Riggio, Alessandro, additional, Salmi, Tuomo, additional, Sanna, Andrea, additional, Santangelo, Andrea, additional, Schatz, Hendrik, additional, Schwenk, Achim, additional, Song, LiMing, additional, Šrámková, Eva, additional, Stappers, Benjamin, additional, Stiele, Holger, additional, Strohmayer, Tod, additional, Tews, Ingo, additional, Tolos, Laura, additional, Török, Gabriel, additional, Tsang, David, additional, Urbanec, Martin, additional, Vacchi, Andrea, additional, Xu, RenXin, additional, Xu, YuPeng, additional, Zane, Silvia, additional, Zhang, GuoBao, additional, Zhang, ShuangNan, additional, Zhang, WenDa, additional, Zheng, ShiJie, additional, and Zhou, Xia, additional

Published
2018
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55. Magnets and Wien Filters for SECAR

Author

BøDker, Franz, Berg, Georg, Couder, Manoel, Hauge, Nils, Kristensen, Jesper, and Schatz, Hendrik

Subjects
04 Hadron Accelerators, Accelerator Physics
Abstract

The Separator for Capture Reactions, SECAR, is being built at Michigan State University for the study of low-energy capture reactions. The high performance magnets and two large Wien filters required to reach the very high recoil mass separation factor are being designed and produced at Danfysik to the SECAR specifications. The 2.4 m long Wien filters with a weight of 35 ton each including a large vacuum tank have high electrode voltages of ±300 kV combined with a magnetic field of 0.12 T. Challenging design requirements for integrated magnetic and electrostatic field homogeneity combined with tight tolerance on the effective lengths have been meet. The dipole magnets for this facility are special in having stringent ±0.5 mm effective magnetic length specifications in a wide excitation range and the transverse field boundary variation is described by a 4th order polynomial. Most of the dipoles are made with variable segmented field clamps in order to keep the deviation of the magnetic fringe field boundary within the required ±0.1 mm. The wide range of different quadrupole, sextupole and octupole magnets are required to meet the specified magnetic length with a tight tolerance., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

Published
2017
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56. Rare isotopes in the cosmos

Author

Schatz, Hendrik

Subjects
Astrophysics -- Research, Heavy elements (Cosmochemistry) -- Atomic properties, Isotopes -- Observations, Universe -- Composition, Physics
Published
2008

58. Enhanced triple-a reaction reduces proton-rich nucleosynthesis in supernovae

Author

Jin, Shilun, Roberts, Luke F., Austin, Sam M., and Schatz, Hendrik

Abstract

The rate of the triple-a reaction that forms 12C affects1,2the synthesis of heavy elements in the Ga–Cd range in proton-rich neutrino-driven outflows of core-collapse supernovae3–5. Initially, these outflows contain only protons and neutrons; these later combine to form a particles, then 12C nuclei via the triple-a reaction, and eventually heavier nuclei as the material expands and cools. Previous experimental work6,7demonstrated that despite the high temperatures encountered in these environments, the reaction is dominated by the well characterized Hoyle state resonance in 12C nuclei. At sufficiently high nucleon densities, however, proton- and neutron-scattering processes may alter the effective width of the Hoyle state8,9. This raises the questions of what the reaction rate in supernova outflows is, and how changes affect nucleosynthesis predictions. Here we report that in proton-rich core-collapse supernova outflows, these hitherto neglected processes enhance the triple-a reaction rate by up to an order of magnitude. The larger reaction rate suppresses the production of heavy proton-rich isotopes that are formed by the ?pprocess3–5(where ?is the neutrino and pis the proton) in the innermost ejected material of supernovae10–13. Previous work on the rate enhancement mechanism9did not anticipate the importance of this enhancement for proton-rich nucleosynthesis. Because the in-medium contribution to the triple-a reaction rate must be present at high densities, this effect needs to be included in supernova nucleosynthesis models. This enhancement also differs from earlier sensitivity studies that explored variations of the unenhanced rate by a constant factor1,2, because the enhancement depends on the evolving thermodynamic conditions. The resulting suppression of heavy-element nucleosynthesis for realistic conditions casts doubt on the ?pprocess being the explanation for the anomalously high abundances of 92,94Mo and 96,98Ru isotopes in the Solar System1,3,14and for the signatures of early Universe element synthesis in the Ga–Cd range found in the spectra of ancient metal-poor stars15–20.

Published
2020
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59. Intermediate-duration burst from AX J1754.2-2754 detected by INTEGRAL

Author

Chenevez, Jérôme, Beeck, Sarah, Brandt, Søren, Kliving, Pernille, Lund, Niels, Kuulkers, Erik, Falanga, Maurizio, K. Galloway, Duncan, Goldwurm, Andrea, Cumming, Andrew, Schatz, Hendrik, Chenevez, Jérôme, Beeck, Sarah, Brandt, Søren, Kliving, Pernille, Lund, Niels, Kuulkers, Erik, Falanga, Maurizio, K. Galloway, Duncan, Goldwurm, Andrea, Cumming, Andrew, and Schatz, Hendrik

Abstract

The JEM-X instrument on-board INTEGRAL has detected a 15-minute long burst from the source AX J1754.2-2754 during an observation of the Galactic Center (PI J. Wilms) on March 12, 2017. This finding has been achieved in the framework of the INTEGRAL monitoring of long X-ray bursts (Chenevez et al. 2008, arXiv:0811.0904) and is only the second burst registered from this source (Chelovekov & Grebenev, ATel #1094; AstL 33, 807, 2007). The 3-25 keV light curve shows that the burst started on MJD 57824.16535 (UT 12 March 2017 03:58:06) with a 30-s rise followed by a 2-minute long plateau at about 70% of the peak level. After the peak, the intensity slowly decreased back to the pre-burst level, which is below our detection threshold, about 15 minutes after the burst start. The burst is shorter in the hard energy band (10-25 keV) with respect to the soft energy band (3-10 keV), lasting only 200 sec. The start of the burst in the hard energy band has a delay of 30 seconds with respect to that of the soft energy band. This coincides with the peak of the burst in the 3-25 keV energy band, at a flux corresponding to 3.3 Crab. A preliminary time-resolved spectral analysis reveals an anti-correlation between the inferred black-body temperature and radius, in the first part of the burst. This is characteristic of a strong photospheric radius expansion phase. The highest flux is reached during the rise of the 3-25 keV light curve at an unabsorbed bolometric value of 7.3 (+/-0.2)×10-8 erg/cm2/s. The source is not detected outside the burst interval, with a 3-σ upper limit of 4 mCrab in the JEM-X range, and the burst is only marginally detected by the IBIS/ISGRI instrument in the 20-40 keV energy band. Previous observations regularly taken since February 13, when the region became visible by INTEGRAL, do not reveal any emission from the source, and we infer a 3-σ upper limit on the persistent flux of 10-10 erg/cm2/s between 3-40 keV. We tentatively interpret this as an intermedia

Published
2017

60. HUBBLE SPACE TELESCOPE NEAR-ULTRAVIOLET SPECTROSCOPY OF BRIGHT CEMP-s STARS

Author

Massachusetts Institute of Technology. Department of Physics, MIT Kavli Institute for Astrophysics and Space Research, Frebel, Anna L., Placco, Vinicius M., Beers, Timothy C., Ivans, Inese I., Filler, Dan, Imig, Julie A., Roederer, Ian U., Abate, Carlo, Hansen, Terese, Cowan, John J., Lawler, James E., Schatz, Hendrik, Sneden, Christopher, Sobeck, Jennifer S., Aoki, Wako, Smith, Verne V., Bolte, Michael, Massachusetts Institute of Technology. Department of Physics, MIT Kavli Institute for Astrophysics and Space Research, Frebel, Anna L., Placco, Vinicius M., Beers, Timothy C., Ivans, Inese I., Filler, Dan, Imig, Julie A., Roederer, Ian U., Abate, Carlo, Hansen, Terese, Cowan, John J., Lawler, James E., Schatz, Hendrik, Sneden, Christopher, Sobeck, Jennifer S., Aoki, Wako, Smith, Verne V., and Bolte, Michael

Abstract

We present an elemental-abundance analysis, in the near-ultraviolet (NUV) spectral range, for the bright carbon-enhanced metal-poor (CEMP) stars HD 196944 (V = 8.40, [Fe/H] = −2.41) and HD 201626 (V = 8.16, [Fe/H] = −1.51), based on data acquired with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope. Both of these stars belong to the sub-class CEMP-s, and exhibit clear over-abundances of heavy elements associated with production by the slow neutron-capture process. HD 196944 has been well-studied in the optical region, but we add abundance results for six species (Ge, Nb, Mo, Lu, Pt, and Au) that are only accessible in the NUV. In addition, we provide the first determination of its orbital period, P = 1325 days. HD 201626 has only a limited number of abundance results based on previous optical work—here we add five new species from the NUV, including Pb. We compare these results with models of binary-system evolution and s-process element production in stars on the asymptotic giant branch, with the goal of explaining their origin and evolution. Our best-fitting models for HD 196944 (M[subscript 1,i] = 0.9M[subscript ʘ], M[subscript 2,i] = 0.86M[subscript ʘ], for [Fe/H] = -2.2), and HD 201626 (M[subscript 1,i] = 0.9M[subscript ʘ], M[subscript 2,i] = 0.76M[subscript ʘ], for [Fe/H] = -2.2; M[subscript 1,i] = 1.6M[subscript ʘ], M[subscript 2,i] = 0.59M[subscript ʘ], for [Fe/H] = -1.5) are consistent with the current accepted scenario for the formation of CEMP-s stars., National Science Foundation (U.S.) (CAREER Grant AST-1255160)

Published
2016

64. Constraining the rp-process by measuring 23Al(d,n)24Si with GRETINA and LENDA at NSCL.

Author

Wolf, Clemens, Langer, Christoph, Fiebiger, Stefan, Reifarth, René, Bazin, Daniel, Bender, Peter, Brown, Alex, Sullivan, Chris, Weisshaar, Dirk, Carlos Zamora, Juan, Montes, Fernando, Pereira, Jorge, Sunghoon Ahn, Schmidt, Konrad, Schmitt, Jaclyn, Titus, Rachel, Schatz, Hendrik, Ayoub, Sara, Browne, Justin, and Deleeuw, Eric

Subjects
ALUMINUM isotopes, NUCLEAR reactions, PROTON capture, SILICON isotopes, X-ray bursts, NUCLEAR physics experiments, KINEMATICS
Abstract

The 23Al(p, γ)24Si stellar reaction rate has a significant impact on the light-curve emitted in X-ray bursts. Theoretical calculations show that the reaction rate is mainly determined by the properties of direct capture as well as low-lying 2+ states and a possible 4+ state in 24Si. Currently, there is little experimental information on the properties of these states. In this proceeding we will present a new experimental study to investigate this reaction, using the surrogate reaction 23Al(d,n) at 47 AMeV at the National Superconducting Cyclotron Laboratory (NSCL). We will discuss our new experimental setup which allows us to use full kinematics employing the Gamma-Ray Energy Tracking In-beam Nuclear Array (GRETINA) to detect the γ-rays following the de-excitation of excited states of the reaction products and the Low Energy Neutron Detector Array (LENDA) to detect the recoiling neutrons. The S800 was used for identification of the 24Si recoils. As a proof of principle to show the feasibility of this concept the Q-value spectrum of 22Mg(d,n)23Al is reconstructed. [ABSTRACT FROM AUTHOR]

Published
2017
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65. X-ray burst studies with the JENSA gas jet target.

Author

Linhardt, Laura E., Schmidt, Konrad, Sunghoon Ahn, Montes, Fernando, Ayoub, Sara, Browne, Justin, Deleeuw, Eric, Wei Jia Ong, Schatz, Hendrik, Hager, Ulrike, Greife, Uwe, Jones, Katherine L., Sachs, Alison, Schmitt, Kyle T., Smith, Karl, Thompson, Paul J., Kontos, Antonios, Kozub, Raymond L., Soares de Bem, Natã F., and Matos, Milan

Subjects
X-ray bursts, TARGETS (Nuclear physics), NUCLEAR reactions, NEUTRON stars, HELIUM isotopes, HYDROGEN isotopes, THERMONUCLEAR reactions in stars
Abstract

When a neutron star accretes hydrogen and helium from the outer layers of its companion star, thermonuclear burning enables the αp-process as a break out mechanism from the hot CNO cycle. Model calculations predict (α, p) reaction rates significantly affect both the light curves and elemental abundances in the burst ashes. The Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas jet target enables the direct measurement of previously inaccessible (α,p) reactions with radioactive beams provided by the rare isotope re-accelerator ReA3 at the National Superconducting Cyclotron Laboratory (NSCL), USA. JENSA is going to be the main target for the Recoil Separator for Capture Reactions (SECAR) at the Facility for Rare Isotope Beams (FRIB). Commissioning of JENSA and first experiments at Oak Ridge National Laboratory (ORNL) showed a highly localized, pure gas target with a density of ∼1019 atoms per square centimeter. Preliminary results are presented from the first direct cross section measurement of the 34Ar(α, p)37 K reaction at NSCL. [ABSTRACT FROM AUTHOR]

Published
2017
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66. Dense matter with eXTP

Author

Watts, Anna, Yu, WenFei, Poutanen, Juri, Zhang, Shu, Bhattacharyya, Sudip, Bogdanov, Slavko, Ji, Long, Patruno, Alessandro, Riley, Thomas, Bakala, Pavel, Baykal, Altan, Bernardini, Federico, Bombaci, Ignazio, Brown, Edward, Cavecchi, Yuri, Chakrabarty, Deepto, Chenevez, Jérôme, Degenaar, Nathalie, Santo, Melania, Salvo, Tiziana, Doroshenko, Victor, Falanga, Maurizio, Ferdman, Robert, Feroci, Marco, Gambino, Angelo, Ge, MingYu, Greif, Svenja, Guillot, Sebastien, Gungor, Can, Hartmann, Dieter, Hebeler, Kai, Heger, Alexander, Homan, Jeroen, Iaria, Rosario, Zand, Jean, Kargaltsev, Oleg, Kurkela, Aleksi, Lai, XiaoYu, Li, Ang, Li, XiangDong, Li, ZhaoSheng, Linares, Manuel, Lu, FangJun, Mahmoodifar, Simin, Méndez, Mariano, Coleman Miller, M., Morsink, Sharon, Nättilä, Joonas, Possenti, Andrea, Prescod-Weinstein, Chanda, Qu, JinLu, Riggio, Alessandro, Salmi, Tuomo, Sanna, Andrea, Santangelo, Andrea, Schatz, Hendrik, Schwenk, Achim, Song, LiMing, Šrámková, Eva, Stappers, Benjamin, Stiele, Holger, Strohmayer, Tod, Tews, Ingo, Tolos, Laura, Török, Gabriel, Tsang, David, Urbanec, Martin, Vacchi, Andrea, Xu, RenXin, Xu, YuPeng, Zane, Silvia, Zhang, GuoBao, Zhang, ShuangNan, Zhang, WenDa, Zheng, ShiJie, and Zhou, Xia

Abstract

In this White Paper we present the potential of the Enhanced X-ray Timing and Polarimetry (eXTP) mission for determining the nature of dense matter; neutron star cores host an extreme density regime which cannot be replicated in a terrestrial laboratory. The tightest statistical constraints on the dense matter equation of state will come from pulse profile modelling of accretion-powered pulsars, burst oscillation sources, and rotation-powered pulsars. Additional constraints will derive from spin measurements, burst spectra, and properties of the accretion flows in the vicinity of the neutron star. Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Sciences, the eXTP mission is expected to be launched in the mid 2020s.

Published
2019
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67. Observatory science with eXTP

Author

in ’t Zand, Jean, Bozzo, Enrico, Qu, JinLu, Li, Xiang-Dong, Amati, Lorenzo, Chen, Yang, Donnarumma, Immacolata, Doroshenko, Victor, Drake, Stephen, Hernanz, Margarita, Jenke, Peter, Maccarone, Thomas, Mahmoodifar, Simin, de Martino, Domitilla, De Rosa, Alessandra, Rossi, Elena, Rowlinson, Antonia, Sala, Gloria, Stratta, Giulia, Tauris, Thomas, Wilms, Joern, Wu, XueFeng, Zhou, Ping, Agudo, Iván, Altamirano, Diego, Atteia, Jean-Luc, Andersson, Nils, Baglio, M., Ballantyne, David, Baykal, Altan, Behar, Ehud, Belloni, Tomaso, Bhattacharyya, Sudip, Bianchi, Stefano, Bilous, Anna, Blay, Pere, Braga, João, Brandt, Søren, Brown, Edward, Bucciantini, Niccolò, Burderi, Luciano, Cackett, Edward, Campana, Riccardo, Campana, Sergio, Casella, Piergiorgio, Cavecchi, Yuri, Chambers, Frank, Chen, Liang, Chen, Yu-Peng, Chenevez, Jérôme, Chernyakova, Maria, Jin, ChiChuan, Ciolfi, Riccardo, Costantini, Elisa, Cumming, Andrew, D’Aì, Antonino, Dai, Zi-Gao, D’Ammando, Filippo, De Pasquale, Massimiliano, Degenaar, Nathalie, Del Santo, Melania, D’Elia, Valerio, Di Salvo, Tiziana, Doyle, Gerry, Falanga, Maurizio, Fan, XiLong, Ferdman, Robert, Feroci, Marco, Fraschetti, Federico, Galloway, Duncan, Gambino, Angelo, Gandhi, Poshak, Ge, MingYu, Gendre, Bruce, Gill, Ramandeep, Götz, Diego, Gouiffès, Christian, Grandi, Paola, Granot, Jonathan, Güdel, Manuel, Heger, Alexander, Heinke, Craig, Homan, Jeroen, Iaria, Rosario, Iwasawa, Kazushi, Izzo, Luca, Ji, Long, Jonker, Peter, José, Jordi, Kaastra, Jelle, Kalemci, Emrah, Kargaltsev, Oleg, Kawai, Nobuyuki, Keek, Laurens, Komossa, Stefanie, Kreykenbohm, Ingo, Kuiper, Lucien, Kunneriath, Devaky, Li, Gang, Liang, En-Wei, Linares, Manuel, Longo, Francesco, Lu, FangJun, Lutovinov, Alexander, Malyshev, Denys, Malzac, Julien, Manousakis, Antonios, McHardy, Ian, Mehdipour, Missagh, Men, YunPeng, Méndez, Mariano, Mignani, Roberto, Mikusincova, Romana, Miller, M., Miniutti, Giovanni, Motch, Christian, Nättilä, Joonas, Nardini, Emanuele, Neubert, Torsten, O’Brien, Paul, Orlandini, Mauro, Osborne, Julian, Pacciani, Luigi, Paltani, Stéphane, Paolillo, Maurizio, Papadakis, Iossif, Paul, Biswajit, Pellizzoni, Alberto, Peretz, Uria, Pérez Torres, Miguel, Perinati, Emanuele, Prescod-Weinstein, Chanda, Reig, Pablo, Riggio, Alessandro, Rodriguez, Jerome, Rodríguez-Gil, Pablo, Romano, Patrizia, Różańska, Agata, Sakamoto, Takanori, Salmi, Tuomo, Salvaterra, Ruben, Sanna, Andrea, Santangelo, Andrea, Savolainen, Tuomas, Schanne, Stéphane, Schatz, Hendrik, Shao, LiJing, Shearer, Andy, Shore, Steven, Stappers, Ben, Strohmayer, Tod, Suleimanov, Valery, Svoboda, Jir̆í, Thielemann, F.-K., Tombesi, Francesco, Torres, Diego, Torresi, Eleonora, Turriziani, Sara, Vacchi, Andrea, Vercellone, Stefano, Vink, Jacco, Wang, Jian-Min, Wang, JunFeng, Watts, Anna, Weng, ShanShan, Weinberg, Nevin, Wheatley, Peter, Wijnands, Rudy, Woods, Tyrone, Woosley, Stan, Xiong, ShaoLin, Xu, YuPeng, Yan, Zhen, Younes, George, Yu, WenFei, Yuan, Feng, Zampieri, Luca, Zane, Silvia, Zdziarski, Andrzej, Zhang, Shuang-Nan, Zhang, Shu, Zhang, Shuo, Zhang, Xiao, and Zingale, Michael

Abstract

In this White Paper we present the potential of the enhanced X-ray Timing and Polarimetry (eXTP) mission for studies related to Observatory Science targets. These include flaring stars, supernova remnants, accreting white dwarfs, low and high mass X-ray binaries, radio quiet and radio loud active galactic nuclei, tidal disruption events, and gamma-ray bursts. eXTP will be excellently suited to study one common aspect of these objects: their often transient nature. Developed by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Science, the eXTP mission is expected to be launched in the mid 2020s.

Published
2019
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68. HUBBLE SPACE TELESCOPENEAR-ULTRAVIOLET SPECTROSCOPY OF BRIGHT CEMP-sSTARS

Author

Placco, Vinicius M., primary, Beers, Timothy C., additional, Ivans, Inese I., additional, Filler, Dan, additional, Imig, Julie A., additional, Roederer, Ian U., additional, Abate, Carlo, additional, Hansen, Terese, additional, Cowan, John J., additional, Frebel, Anna, additional, Lawler, James E., additional, Schatz, Hendrik, additional, Sneden, Christopher, additional, Sobeck, Jennifer S., additional, Aoki, Wako, additional, Smith, Verne V., additional, and Bolte, Michael, additional

Published
2015
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69. HIGH-RESOLUTION ABUNDANCE ANALYSIS OF VERY METAL-POOR R-I STARS

Author

Siqueira Mello, Cesar, primary, Hill, Vanessa, additional, Barbuy, Beatriz, additional, Spite, Monique, additional, Spite, Francois, additional, Beers, Timothy, additional, Caffau, Elisabetta, additional, Bonifacio, Piercarlo, additional, Cayrel, Roger, additional, Francois, Patrick, additional, Schatz, Hendrik, additional, and Wanajo, Shinya, additional

Published
2015
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72. HUBBLE SPACE TELESCOPENEAR-ULTRAVIOLET SPECTROSCOPY OF THE BRIGHT CEMP-NO STAR BD+44°493

Author

Placco, Vinicius M., primary, Beers, Timothy C., additional, Roederer, Ian U., additional, Cowan, John J., additional, Frebel, Anna, additional, Filler, Dan, additional, Ivans, Inese I., additional, Lawler, James E., additional, Schatz, Hendrik, additional, Sneden, Christopher, additional, Sobeck, Jennifer S., additional, Aoki, Wako, additional, and Smith, Verne V., additional

Published
2014
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73. Detection of the Second R-Process Peak Element Tellurium in Metal-Poor Stars

Author

Massachusetts Institute of Technology. Department of Physics, MIT Kavli Institute for Astrophysics and Space Research, Frebel, Anna L., Roederer, Ian U., Lawler, James E., Cowan, John J., Beers, Timothy C., Ivans, Inese I., Schatz, Hendrik, Sobeck, Jennifer S., Sneden, Christopher, Massachusetts Institute of Technology. Department of Physics, MIT Kavli Institute for Astrophysics and Space Research, Frebel, Anna L., Roederer, Ian U., Lawler, James E., Cowan, John J., Beers, Timothy C., Ivans, Inese I., Schatz, Hendrik, Sobeck, Jennifer S., and Sneden, Christopher

Abstract

Using near-ultraviolet spectra obtained with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope, we detect neutral tellurium in three metal-poor stars enriched by products of r-process nucleosynthesis, BD +17 3248, HD 108317, and HD 128279. Tellurium (Te, Z = 52) is found at the second r-process peak (A ≈ 130) associated with the N = 82 neutron shell closure, and it has not been detected previously in Galactic halo stars. The derived tellurium abundances match the scaled solar system r-process distribution within the uncertainties, confirming the predicted second peak r-process residuals. These results suggest that tellurium is predominantly produced in the main component of the r-process, along with the rare earth elements.

Published
2013

74. New Hubble Space Telescope Observations of Heavy Elements in Four Metal-Poor Stars

Author

Massachusetts Institute of Technology. Department of Physics, MIT Kavli Institute for Astrophysics and Space Research, Frebel, Anna L., Roederer, Ian U., Lawler, James E., Sobeck, Jennifer S., Beers, Timothy C., Cowan, John J., Ivans, Inese I., Schatz, Hendrik, Sneden, Christopher, Thompson, Ian B., Massachusetts Institute of Technology. Department of Physics, MIT Kavli Institute for Astrophysics and Space Research, Frebel, Anna L., Roederer, Ian U., Lawler, James E., Sobeck, Jennifer S., Beers, Timothy C., Cowan, John J., Ivans, Inese I., Schatz, Hendrik, Sneden, Christopher, and Thompson, Ian B.

Abstract

Elements heavier than the iron group are found in nearly all halo stars. A substantial number of these elements, key to understanding neutron-capture nucleosynthesis mechanisms, can only be detected in the near-ultraviolet. We report the results of an observing campaign using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope to study the detailed heavy-element abundance patterns in four metal-poor stars. We derive abundances or upper limits from 27 absorption lines of 15 elements produced by neutron-capture reactions, including seven elements (germanium, cadmium, tellurium, lutetium, osmium, platinum, and gold) that can only be detected in the near-ultraviolet. We also examine 202 heavy-element absorption lines in ground-based optical spectra obtained with the Magellan Inamori Kyocera Echelle Spectrograph on the Magellan-Clay Telescope at Las Campanas Observatory and the High Resolution Echelle Spectrometer on the Keck I Telescope on Mauna Kea. We have detected up to 34 elements heavier than zinc. The bulk of the heavy elements in these four stars are produced by r-process nucleosynthesis. These observations affirm earlier results suggesting that the tellurium found in metal-poor halo stars with moderate amounts of r-process material scales with the rare earth and third r-process peak elements. Cadmium often follows the abundances of the neighboring elements palladium and silver. We identify several sources of systematic uncertainty that must be considered when comparing these abundances with theoretical predictions. We also present new isotope shift and hyperfine structure component patterns for Lu II and Pb I lines of astrophysical interest.

Published
2013

78. \beta -decay and neutron emission studies of r-process nuclei near 137Sb

Author

Smith, Karl, primary, Attallah, F., additional, Faestermann, T, additional, Giesen, U, additional, Geissel, H., additional, Hannawald, M, additional, Hausmann, M, additional, Hellström, M., additional, Kessler, Ruben, additional, Kratz, K.-L., additional, Mahmud, H, additional, Litvinov, Yuri, additional, Mineva, M. N., additional, Montes, Fernando, additional, Münzenberg, G, additional, Pfeiffer, B., additional, Pereira Conca, Jorge, additional, Santi, Peter, additional, Schatz, Hendrik, additional, Scheidenberger, C, additional, Schmidt, K, additional, Schneider, R, additional, Stolz, Andreas, additional, Sümmerer, K., additional, Stadlmann, J, additional, Wefers, E, additional, and Woods, P. J., additional

Published
2011
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79. Mass measurements of neutron rich isotopes in the Fe region and electron capture processes in neutron star crusts

Author

Estrade, Alfredo, primary, Matos, Milan, additional, Schatz, Hendrik, additional, Amthor, Matthew, additional, Beard, Mary, additional, Brown, Ed, additional, Bazin, Daniel, additional, Becerril, Ana, additional, Elliot, Thom, additional, Gade, Alexandra, additional, Galaviz, Daniel, additional, Gupta, Sanjib S., additional, Lorusso, Giuseppe, additional, Lau, Rita, additional, Möller, Peter, additional, Pereira, Jorge, additional, Portillo, Mauricio, additional, Rogers, Andrew M., additional, Shapira, Dan, additional, Smith, Ed, additional, Stolz, Andreas, additional, Wallace, Mark, additional, and Michael, Wiescher, additional

Published
2011
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80. r-process experimental campaign at the National Superconducting Cyclotron Laboratory (NSCL/MSU)

Author

Pereira, Jorge, primary, Becerril Reyes, Ana Delia, additional, Elliot, Thom, additional, Estrade, Alfredo, additional, Galaviz, Daniel, additional, Kern, Linda, additional, Lorusso, G., additional, Mantica, Paul, additional, Matos, Milan, additional, Montes, Fernando, additional, Schatz, Hendrik, additional, Hennrich, Stefan, additional, Kratz, Karl Ludwig, additional, Arndt, Oliver, additional, Kessler, Ruben, additional, Schertz, Florian, additional, Pfeiffer, Bernd, additional, Quinn, Matthew, additional, Aprahamian, Ani, additional, Wöhr, Andreas, additional, Smith, Edward, additional, and Walters, William, additional

Published
2010
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86. Time of flight mass measurements of neutron rich nuclides relevant to astrophysical processes

Author

Estrade, Alfredo, primary, Matos, Milan, additional, Amthor, A. Matthew, additional, Bazin, Daniel, additional, Becerril Reyes, Ana Delia, additional, Elliot, Thom, additional, Gade, Alexandra, additional, Galaviz, Daniel, additional, Lorusso, Giuseppe, additional, Pereira, Jorge, additional, Portillo, Mauricio, additional, Rogers, Andrew, additional, Schatz, Hendrik, additional, Stolz, Andreas, additional, Shapira, Dan, additional, Smith, Edward, additional, and Wallace, Mark, additional

Published
2010
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87. THE JINA REACLIB DATABASE: ITS RECENT UPDATES AND IMPACT ON TYPE-I X-RAY BURSTS

Author

Cyburt, Richard H., primary, Amthor, A. Matthew, additional, Ferguson, Ryan, additional, Meisel, Zach, additional, Smith, Karl, additional, Warren, Scott, additional, Heger, Alexander, additional, Hoffman, R. D., additional, Rauscher, Thomas, additional, Sakharuk, Alexander, additional, Schatz, Hendrik, additional, Thielemann, F. K., additional, and Wiescher, Michael, additional

Published
2010
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89. Design of a New Recoil Separator for Measurements of Radiative Capture Reactions in Astrophysics

Author

Berg, Georg P. A., primary, Blackmon, Jeff C., additional, Couder, Manoel, additional, Greife, U., additional, Montes, F., additional, Rehm, K. Ernst, additional, Schatz, Hendrik, additional, Smith, Michael S., additional, Wiescher, Michael, additional, Zeller, Al, additional, Tanihara, Isao, additional, Ong, Hooi Jin, additional, Tamii, Atsushi, additional, Kishimoto, Tadafumi, additional, Kajino, Toshitaka, additional, Kubono, Shigeru, additional, and Shima, Tatsushi, additional

Published
2010
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90. Breakout from the hot CNO cycle via the ne-18 (alpha ,p) Na-21 reaction. 2. Extended energy range Ec.m. approximately 1.7-Mev to 2.9-MeV

Author

UCL - SC/PHYS - Département de physique, Groombridge, D., Shotter, A.C., Bradfield-Smith, W., Cherubini, S., Davinson, T., Di Pietro, A., Gorres, J., Graulich, J.S., Laird, A.M., Musumarra, A., Ostrowski, A.N., Rahighi, J., Schatz, Hendrik, Wiescher, M., Woods, P.J., Leleux, Pierre, Ninane, Alain, UCL - SC/PHYS - Département de physique, Groombridge, D., Shotter, A.C., Bradfield-Smith, W., Cherubini, S., Davinson, T., Di Pietro, A., Gorres, J., Graulich, J.S., Laird, A.M., Musumarra, A., Ostrowski, A.N., Rahighi, J., Schatz, Hendrik, Wiescher, M., Woods, P.J., Leleux, Pierre, and Ninane, Alain

Published
2002

91. Study of astrophysically important states in 26Si with the p(25Al,p)25Al elastic scattering

Author

Chen, Jun, primary, Chen, Alan A., additional, Amadio, G., additional, Bazin, Daniel, additional, Becerril Reyes, Ana Delia, additional, Amthor, A. Matthew, additional, Cherubini, S., additional, Galaviz Redondo, Daniel, additional, Gade, Alexandra, additional, Glasmacher, T., additional, Fujikawa, H., additional, Iwasa, N., additional, He, J.J., additional, Hayakawa, Seiya, additional, Kahl, David, additional, Khiem, L. H., additional, Kubono, S., additional, Kurihara, Y., additional, Kwon, Young Kwan, additional, Lorusso, Giuseppe, additional, Matos, Milan, additional, Moon, J.Y., additional, Niikura, M., additional, Nishimura, S., additional, Odahara, A., additional, Ouellet, Christian Van, additional, Pearson, Jonty, additional, Pereira, Jorge, additional, Pizzone, Rosario G., additional, Sidoti, Antonio, additional, Schatz, Hendrik, additional, Smith, Karl, additional, Teranishi, T., additional, Togano, Y., additional, Wales, B., additional, Wakabayashi, Y., additional, Yamaguchi, Y., additional, and Zegers, Remco, additional

Published
2009
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92. Beta-Decay Study of the rp-Process Nucleus 96Cd

Author

Becerril Reyes, Ana Delia, primary, Amthor, A. Matthew, additional, baumann, thomas, additional, Bazin, Daniel, additional, Estrade, Alfredo, additional, Hitt, George, additional, Lorusso, Giuseppe, additional, Mantica, Paul, additional, Meharchand, Rhiannon, additional, Montes, Fernando, additional, Pereira, Jorge, additional, Portillo, Mauricio, additional, Perdikakis, Georgios, additional, Schatz, Hendrik, additional, Smith, Karl, additional, Stoker, Joshua, additional, and Zegers, Remco, additional

Published
2009
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93. Beta-Decay Half Life of 84Mo

Author

Stoker, Joshua, primary, Mantica, Paul, additional, Bazin, Daniel, additional, Becerril Reyes, Ana Delia, additional, Berryman, Jill S., additional, Crawford, Heather L., additional, Estrade, Alfredo, additional, Guess, Carol, additional, Hitt, George, additional, Lorusso, Giuseppe, additional, Matos, Milan, additional, Minamisono, Kei, additional, Montes, Fernando, additional, Pereira, Jorge, additional, Perdikakis, Georgios, additional, Schatz, Hendrik, additional, Smith, Karl, additional, and Zegers, Remco, additional

Published
2009
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94. Sensitivity of X-Ray Burst Models to Uncertainties in Nuclear Processes

Author

Smith, Karl, primary, Amthor, A. Matthew, additional, Cyburt, Richard, additional, Ferguson, Ryan, additional, Heger, Alexander, additional, Johnson, Emily, additional, Klein, Matthew, additional, Meisel, Zachary, additional, Rauscher, Thomas, additional, Sakharuk, Alexander, additional, Schatz, Hendrik, additional, Warren, Scott, additional, and Michael, Wiescher, additional

Published
2009
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96. Alpha decay of 109I and the implications for the rapid-proton capture process

Author

Mazzocchi, Chiara, primary, Grzywacz, Robert, additional, Liddick, S. N., additional, Rykaczewski, Krzysztof P., additional, Schatz, Hendrik, additional, Batchelder, J. C., additional, Bingham, C. R., additional, Cartegni, L., additional, Gross, C. J., additional, Hamilton, J. H., additional, Hwang, J.K., additional, Ilyushkin, S., additional, Korgul, A., additional, Krolas, Wojciech, additional, Li, K., additional, page, R. D., additional, and Winger, J. A., additional

Published
2009
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97. Improved Mass Measurements of Nuclei Around N=Z=34

Author

Savory, Joshua, primary, Bachelet, Cyril, additional, Block, Michael, additional, Bollen, George, additional, Facina, Marius, additional, Folden, Cody M., additional, Guénaut, C., additional, Kwan, E., additional, Kwiatkowski, Ania A., additional, Morrisey, Dave J., additional, Pang, Greg K., additional, Prinke, Amanda, additional, Ringle, Ryan, additional, Schatz, Hendrik, additional, Schwarz, Stefan, additional, and Sumithrarachchi, C. S., additional

Published
2009
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100. Thermonuclear Reaction Rate Libraries and Software Tools for Nuclear Astrophysics Research

Author

Smith, Michael S., primary, Cyburt, Richard, additional, Schatz, Hendrik, additional, Wiescher, Michael, additional, Smith, Karl, additional, Warren, Scott, additional, Ferguson, Ryan, additional, Lingerfelt, Eric, additional, Buckner, Kim, additional, Nesaraja, Caroline D., additional, Suda, Takuma, additional, Nozawa, Takaya, additional, Ohnishi, Akira, additional, Kato, Kiyoshi, additional, Fujimoto, Masayuki Y., additional, Kajino, Toshitaka, additional, and Kubono, Shigeru, additional

Published
2008
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