SFB 634: Nuclear Structure, Nuclear Astrophysics and Fundamental Experiments at Low Momentum Transfer at the Superconducting Darmstadt Electron Accelerator S-DALINAC
Final Report Abstract
The Collaborative Research Center 634 “Nuclear Structure, Nuclear Astrophysics and Fundamental Experiments at Low Momentum Transfer at the Superconducting Darmstadt Electron Accelerator (SDALINAC)” addressed the scientific exploitation and technological advancement of the superconducting particle accelerator S-DALINAC set up at the Technische Universität Darmstadt. It accelerates electrons in strong electric fields oscillating with high frequency in superconducting microwave resonators and thereby provides energetic beams of accelerated electrons and photons. The latter are produced in bremsstrahlung processes of electrons in matter. The particle beams are sufficiently energetic to raise atomic nuclei to excited quantum states. Corresponding nuclear reactions can be observed with appropriate detector systems. Data obtained this way are prerequisites for scientific progress in intertwined research areas in nuclear physics and nuclear astrophysics. The CRC 634 was organized in five linked project areas that addressed scientific challenges from the research fields of (A) nuclear structure physics, (B) nuclear astrophysics, (C) fundamental experiments, (D) theoretical nuclear structure physics, and (E) accelerator development. Scientists from the disciplines of experimental nuclear physics, theoretical physics, and electrical engineering collaborated closely within the scope of the CRC 634. In doing so more than 400 scientific articles were published in refereed journals and 70 early-stage researchers have finished the doctoral theses based on the scientific research successfully conducted in the CRC. Among other things the scientists in the CRC 634 investigated the properties of heavy atomic nuclei, built up from many protons and neutrons, in oscillating electromagnetic fields with high oscillation frequencies. This was achieved by exposing the nuclei to intense beams of short-wavelength photons or to electromagnetic pulses in scattering reactions with electrons or other electrically charged particles. The data obtained within the CRC and their theoretical interpretations contributed considerably to the observation and the understanding of the so-called pygmy dipole resonance of atomic nuclei. It manifests itself in nuclei made out of more neutrons than protons in an excessive probability for reactions with comparatively low-energy photons and is understood as a partial density oscillation of neutrons versus protons within the atomic nucleus. The properties of the pygmy dipole resonance are sensitive to the local density dependence of the nuclear forces between protons and neutrons. The new insights contribute to a better understanding of extreme cosmic objects such as neutron stars or of the processes along the natural synthesis of heavy chemical elements in exploding stars such as supernovae. Scientists in the CRC 634 furthermore succeeded in observing a new radioactive decay phenomenon. Excited quantum states of atomic nuclei may eventually decay by simultaneous emission of two gamma quanta instead of a single one. This so-called competitive double-gamma nuclear decay has gone undetected since its theoretical postulation based on quantum-mechanical calculations some 85 years ago. It was identified in the CRC by using novel gamma-ray detectors with increased time-resolution capabilities that enabled the scientists to discriminate the simultaneous gamma emissions from the background. Theoretical analyses performed within the CRC offered a quantitative understanding of these observations. Further scientific results out of many obtained within the CRC 634 concerned, e.g., the development of new techniques for measuring fundamental properties of the proton, such as its charge radius and its electric and magnetic polarizabilities, or insight into chaotic properties of excited states of quantum systems by means of their simulation in superconducting microwave resonators with various shapes and properties. Theoretical methods for quantitatively understanding the properties of atomic nuclei based on the fundamental theory of quantum chromo dynamics (QCD) were considerably advanced within the CRC and also applied to an improved understanding of astrophysical processes in cosmic objects such as neutron stars or supernovae. A closely collaborating team of physicists and electrical engineers managed to technologically upgrade the S-DALINAC providing now electron beams of enhanced stability and improved energy spread. Within the scope of the CRC the S-DALINAC was advanced to the first particle accelerator in Germany capable of being operated in the mode of an energy recovery linac (ERL) in which the kinetic energy of the accelerated beam particles can be recovered to a large extent on their deceleration after experimental usage.
Publications
- Ab Initio Study of 40Ca with an Importance Truncated No-Core Shell Model. Phys. Rev. Lett. 99 (2007) 092501
R. Roth and P. Navrátil
- Gamow-Teller Strength in the Exotic Odd-Odd Nuclei 138La and 180Ta and Its Relevance for Neutrino Nucleosynthesis. Phys. Rev. Lett. 98 (2007) 082501
A. Byelikov, T. Adachi, H. Fujita, K. Fujita, Y. Fujita, K. Hatanaka, A. Heger, Y. Kalmykov, K. Kawase, K. Langanke, G. Martínez-Pinedo, K. Najanishi, P. von Neumann-Cosel, R. Neveling, A. Richter, N. Sakamoto, Y. sakemi, A. Shevchenko, A. Shimbara, Y. Shimizu, F.D. Smit, Y. Tameshige, A. Tamii, S.E. Woosley and M. Yosei
- High-Energy-Resolution Inelastic Electron and Proton Scattering and the Multiphonon Nature of Mixed-Symmetry 2+ States in 94Mo. Phys. Rev. Lett. 99 (2007) 092503
O. Burda, N. Botha, J. Carter, R. W. Fearick, S. V. Förtsch, C. Fransen, H. Fujita, J. D. Holt, M. Kuhar, A. Lenhardt, P. von Neumann-Cosel, R. Neveling, N. Pietralla, V. Y. Ponomarev, A. Richter, O. Scholten, E. Sideras-Haddad, F. D. Smit and J. Wambach
- Induced Time-Reversal Symmetry Breaking Observed in Microwave Billiards. Phys. Rev. Lett. 98 (2007) 074103
B. Dietz, T. Friedrich, H.L. Harney, M. Miski-Oglu, A. Richter, F. Schäfer and H.A. Weidenmüller
- Spin- and Parity-Resolved Level Densities from the Fine Structure of Giant Resonances. Phys. Rev. Lett. 99 (2007) 202502
Y. Kalmykov, C. Özen, K. Langanke, G. Martínez-Pinedo, P. von Neumann-Cosel and A. Richter
- Structure of the Hoyle State in 12C. Phys. Rev. Lett. 98 (2007) 032501
M. Chernykh, H. Feldmeier, T. Neff, P. von Neumann-Cosel and A. Richter
- Experiments on multiphonon states with proton-neutron mixed symmetry in vibrational nuclei. Prog. Part. Nucl. Phys. 60 (2008) 225
N. Pietralla, P. von Brentano and A. Lisetskiy
- Fine Structure of the Pygmy Dipole Resonance in 136Xe. Phys. Rev. Lett. 100 (2008) 232501
D. Savran, M. Fritzsche, J. Hasper, K. Lindenberg, S. Müller, V. Y. Ponomarev, K. Sonnabend and A. Zilges
- Measurement of the Reaction 2H(e,e'). Phys. Rev. Lett. 100 (2008) 172501
N. Ryezayeva, H. Arenhövel, O. Burda, A. Byelikov, M. Chernykh, J. Enders, H. W. Grießhammer, Y. Kalmykov, P. von Neumann-Cosel, B. Özel, I. Poltoratska, I. Pysmenetska, C. Rangacharyulu, S. Rathi, A. Richter, G. Schrieder, A. Shevchenko and O. Yevetska
- Nonthermal Fixed Points: Effective Weak Coupling for Strongly Correlated Systems Far from Equilibrium. Phys. Rev. Lett. 101 (2008) 041603
J. Berges, A. Rothkopf and J. Schmidt
- Superscars in Billiards: A Model for Doorway States in Quantum Spectra. Phys. Rev. Lett. 100 (2008) 204101
S. Åberg, T. Guhr, M. Miski-Oglu and A. Richter
- Induced Violation of Time-Reversal Invariance in the Regime of Weakly Overlapping Resonances. Phys. Rev. Lett. 103 (2009) 064101
B. Dietz, T. Friedrich, H. L. Harney, M. Miski-Oglu, A. Richter, F. Schäfer, J. Verbaarschot and H. A. Weidenmüller
- Isospin character of the pygmy dipole resonance in 124Sn. Phys. Rev. Lett. 105 (2010) 212503
J. Endres, E. Litvinova, D. Savran, P.A. Butler, M.N. Harakeh, S. Harissopulos, R.-D. Herzberg, R. Krücken, A. Lagoyannis, N. Pietralla, V.Yu. Ponomarev, L. Popescu, P. Ring, M. Scheck, K. Sonnabend, V.I. Stoica, H.J. Wörtche, and A. Zilges
- Magnetic dipole excitations in nuclei: Elementary modes of nucleonic motion. Rev. Mod. Phys. 82 (2010) 2365
K. Heyde, P. von Neumann-Cosel and A. Richter
- Pair Decay Width of the Hoyle State and its Role for Stellar Carbon Production. Phys. Rev. Lett. 105 (2010) 022501
M. Chernykh, H. Feldmeier, T. Neff, P. von Neumann-Cosel and A. Richter
- Random Matrices and Chaos in Nuclear Physics: Nuclear Reactions. Rev. Mod. Phys. 82 (2010) 2845
G. E. Mitchell, A. Richter, and H. A. Weidenmüller
- Complete Electric Dipole Response and the Neutron Skin in 208Pb. Phys. Rev. Lett. 107 (2011) 062502
A. Tamii, I. Poltoratska, P. von Neumann-Cosel, Y. Fujita, T. Adachi, C. Bertulani, J. Carter, M. Dozono, H. Fujita, K. Fujita, K. Hatanaka, D. Ishikawa, M. Itoh, T. Kawabata, Y. Kalmykov, A.M. Krumbholz, E. Litvinova, H. Msubara, K. Nakanishi, R. Neveling, H. Okamura, H. Ong, B. Özel-Tashenov, V.Yu. Ponomarev, A. Richter, B. Rubio, H. Sakaguchi, Y. Sakemi, Y. Sasamoto, Y. Shimbara, Y. Shimizu, F. Smit, T. Suzuki, Y. Tameshige, J. Wambach, R. Yamada, M. Yosoi, J. Zenihiro
- Origin of Low-Energy Quadrupole Collectivity in Vibrational Nuclei. Phys. Rev. Lett. 106 (2011) 062501
C. Walz, H. Fujita, A. Krugmann, P. von Neumann-Cosel, N. Pietralla, V.Yu. Ponomarev, A. Scheikh-Obeid, J. Wambach
- Charged-Current Weak Interaction Processes in Hot and Dense Matter and its Impact on the Spectra of Neutrinos Emitted from Protoneutron Star Cooling. Phys. Rev. Lett. 109 (2012) 251104
G. Martínez-Pinedo, T. Fischer, A. Lohs, and L. Huther
(See online at https://doi.org/10.1103/PhysRevLett.109.251104) - Medium-Mass Nuclei with Normal-Ordered Chiral NN+3N Interactions. Phys. Rev. Lett. 109 (2012) 052501
Robert Roth, Sven Binder, Klaus Vobig, Angelo Calci, Joachim Langhammer, and Petr Navrátil
(See online at https://doi.org/10.1103/PhysRevLett.109.052501) - Polarization Transfer of Bremsstrahlung Arising from Spin-Polarized Electrons. Phys. Rev. Lett. 108 (2012) 264801
R. Märtin, G. Weber, R. Barday, Y. Fritzsche, U. Spillmann, W. Chen, R. D. DuBois, J. Enders, M. Hegewald, S. Hess, A. Surzhykov, D. B. Thorn, S. Trotsenko, M. Wagner, D. F. A. Winters, V. A. Yerokhin, and Th. Stöhlker
(See online at https://doi.org/10.1103/PhysRevLett.108.264801) - PT Symmetry and Spontaneous Symmetry Breaking in a Microwave Billiard. Phys. Rev. Lett. 108 (2012) 024101
S. Bittner, B. Dietz, U. Günther, H. L. Harney, M. Miski-Oglu, A. Richter, and F. Schäfer
(See online at https://doi.org/10.1103/PhysRevLett.108.024101) - Ab Initio Calculations of Even Oxygen Isotopes with Chiral Two-Plus-Three-Nucleon Interactions. Phys. Rev. Lett. 110 (2013) 242501
H. Hergert, S. Binder, A. Calci, J. Langhammer, and R. Roth
(See online at https://doi.org/10.1103/PhysRevLett.110.242501) - Constraint on 0νββ Matrix Elements from a Novel Decay Channel of the Scissors Mode: The Case of 154Gd. Phys. Rev. Lett. 111 (2013) 172501
J. Beller, N. Pietralla, J. Barea, M. Elvers, J. Endres, C. Fransen, J. Kotila, O. Möller, A. Richter, T. R. Rodriguez, C. Romig, D. Savran, M. Scheck, L. Schnorrenberger, K. Sonnabend, V. Werner, A. Zilges, and M. Zweidinger
- Distribution of Scattering Matrix Elements in Quantum Chaotic Scattering. Phys. Rev. Lett. 111 (2013) 030403
S. Kumar, A. Nock, H.-J. Sommers, T. Guhr, B. Dietz, M. Miski-Oglu, A. Richter, and F. Schäfer
(See online at https://doi.org/10.1103/PhysRevLett.111.030403) - Experimental studies of the Pygmy Dipole Resonance. Prog. Part. Nucl. Phys. 70 (2013) 210
D. Savran, T. Aumann, A. Zilges
(See online at https://doi.org/10.1016/j.ppnp.2013.02.003) - Imaginary Polarization as a Way to Surmount the Sign Problem in Ab Initio Calculations of Spin-Imbalanced Fermi Gases. Phys. Rev. Lett. 110 (2013) 130404
Jens Braun, Jiunn-Wei Chen, Jian Deng, Joaquín E. Drut, Bengt Friman, Chen-Te Ma, and Yu-Dai Tsai
(See online at https://doi.org/10.1103/PhysRevLett.110.130404) - Neutron Matter at Next-to-Next-to-Next-to-Leading Order in Chiral Effective Field Theory. Phys. Rev. Lett. 110 (2013) 032504
I. Tews, T. Krüger, K. Hebeler, and A. Schwenk
(See online at https://doi.org/10.1103/PhysRevLett.110.032504) - Quantum Monte Carlo Calculations with Chiral Effective Field Theory Interactions. Phys. Rev. Lett. 111 (2013) 032501
A. Gezerlis, I. Tews, E. Epelbaum, S. Gandolfi, K. Hebeler, A. Nogga, and A. Schwenk
(See online at https://doi.org/10.1103/PhysRevLett.111.032501) - Three-Body Forces and Proton-Rich Nuclei. Phys. Rev. Lett. 110 (2013) 022502
J. D. Holt, J. Menéndez, and A. Schwenk
(See online at https://doi.org/10.1103/PhysRevLett.110.022502) - Ab Initio Description of p-Shell Hypernuclei. Phys. Rev. Lett. 113 (2014) 192502
Roland Wirth, Daniel Gazda, Petr Navrátil, Angelo Calci, Joachim Langhammer, Robert Roth
(See online at https://doi.org/10.1103/PhysRevLett.113.192502) - Breakdown of the Isobaric Multiplet Mass Equation for the A=20 and 21 Multiplets. Phys. Rev. Lett. 113 (2014) 082501
A. T. Gallant, M. Brodeur, C. Andreoiu, A. Bader, A. Chaudhuri, U. Chowdhury, A. Grossheim, R. Klawitter, A. A. Kwiatkowski, K. G. Leach, A. Lennarz, T. D. Macdonald, B. E. Schultz, J. Lassen, H. Heggen, S. Raeder, A. Teigelhöfer, B. A. Brown, A. Magilligan, J. D. Holt, J. Menéndez, J. Simonis, A. Schwenk, and J. Dilling
(See online at https://doi.org/10.1103/PhysRevLett.113.082501) - Nonperturbative Shell-Model Interactions from the In-Medium Similarity Renormalization Group. Phys. Rev. Lett. 113 (2014) 142501
S. K. Bogner, H. Hergert, J. D. Holt, A. Schwenk, S. Binder, A. Calci, J. Langhammer, and R. Roth
(See online at https://doi.org/10.1103/PhysRevLett.113.142501) - Observation of Low- and High-Energy Gamow-Teller Phonon Excitations in Nuclei. Phys. Rev. Lett. 112 (2014) 112502
Y. Fujita, H. Fujita, T. Adachi, C.L. Bai, A. Algora, G.P.A. Berg, P. von Brentano, G. Colò, M. Csatlós, J. M. Deaven, E. Estevez-Aguado, C. Fransen, D. De Frenne, K. Fujita, E. Ganioğlu, C. J. Guess, J. Gulyás, K. Hatanaka, K. Hirota, M. Honma, D. Ishikawa, E. Jacobs, A. Krasznahorkay, H. Matsubara, K. Matsuyanagi, R. Meharchand, F. Molina, K. Muto, K. Nakanishi, A. Negret, H. Okamura, H. J. Ong, T. Otsuka, N. Pietralla, G. Perdikakis, L. Popescu, B. Rubio, H. Sagawa, P. Sarriguren, C. Scholl, Y. Shimbara, Y. Shimizu, G. Susoy T. Suzuki, Y. Tameshige, A. Tamii, J.H. Thies, M. Uchida, T.Wakasa, M. Yosoi, R. G. T. Zegers, K. O. Zell, and J. Zenihiro
(See online at https://doi.org/10.1103/PhysRevLett.112.112502) - Quantum Monte Carlo Calculations of Light Nuclei Using Chiral Potentials. Phys. Rev. Lett. 113 (2014) 192501
J. E. Lynn, J. Carlson, E. Epelbaum, S. Gandolfi, A. Gezerlis, and A. Schwenk
(See online at https://doi.org/10.1103/PhysRevLett.113.192501) - Supernova Matter at Subnuclear Densities as a Resonant Fermi Gas: Enhancement of Neutrino Rates. Phys. Rev. Lett. 113 (2014) 081101
A. Bartl, C. J. Pethick, and A. Schwenk
(See online at https://doi.org/10.1103/PhysRevLett.113.081101) - Fullerene C60 Simulated with a Superconducting Microwave Resonator and Test of the Atiyah- Singer Index Theorem. Phys. Rev. Lett. 115 (2015) 026801
B. Dietz, T. Klaus, M. Miski-Oglu, A. Richter, M. Bischoff, L. von Smekal, and J. Wambach
(See online at https://doi.org/10.1103/PhysRevLett.115.026801) - Neutron and weak-charge distributions of the 48Ca nucleus. Nature Physics (2015)
G. Hagen, A. Ekström, C. Forssén, G.R. Jansen, W. Nazarewicz, T.Papenbrock, K.A.Wendt, S. Bacca, N. Barnea, B. Carlsson, C. Drischler, K. Hebeler, M. Hjorth-Jensen, M. Miorelli, G. Orlandini, A. Schwenk, J. Simonis
(See online at https://doi.org/10.1038/NPHYS3529) - Non-Quenched Isoscalar Spin-M1 Excitations in sd-Shell Nuclei. Phys. Rev. Lett. 115 (2015) 102501
H. Matsubara, A. Tamii, H. Nakada, T. Adachi, J. Carter, M. Dozono, H. Fujita, K.Fujita, Y. Fujita, K. Hatanaka, W. Horiuchi, M. Itoh, T. Kawabata, S. Kuroita, Y. Maeda, P. Navratil, P. von Neumann-Cosel, R. Neveling, H. Okamura, L. Popescu, I. Poltoratska, A. Richter, B. Rubio, H. Sakaguchi, S. Sakaguchi, Y. Sakemi, Y. Sasamoto, Y. Shimbara, Y. Shimizu, F.D. Smit, K. Suda, Y. Tameshige, H. Tokieda, Y. Yamada, M. Yosoi, J. Zenihiro
(See online at https://doi.org/10.1103/PhysRevLett.115.102501) - Observation of the competitive double-gamma nuclear decay. Nature 526 (2015) 406
C. Walz, H. Scheit, N. Pietralla, T. Aumann, R. Lefol, V.Yu. Ponomarev
(See online at https://doi.org/10.1038/nature15543)
