WorldWideScience

Sample records for cooled proton-rich nuclei

  1. Structure of proton-rich nuclei of astrophysical interest

    Energy Technology Data Exchange (ETDEWEB)

    Roeckl, E. [Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt (Germany)

    1998-06-01

    Recent experimental data concerning proton-rich nuclei between A=20 and A=100 are presented and discussed with respect to their relevance to the astrophysical rp process and to the calibration of solar neutrino detectors. (orig.)

  2. Mass Measurements of Proton-rich Nuclei with JYFLTRAP

    OpenAIRE

    Eronen, Tommi

    2011-01-01

    The Penning trap setup JYFLTRAP, connected to the IGISOL facility, has been extensively used for atomic mass measurements of exotic nuclei. On the proton rich side of the chart of nuclei mass measurements have mostly contributed to fundamental physics and nuclear astrophysics studies with about 100 atomic masses measured.

  3. Production of proton-rich nuclei around Z=84-90 in fusion-evaporation reactions

    CERN Document Server

    Chen, Peng-Hui; Niu, Fei; Guo, Ya-Fei; Zhang, Hong-Fei; Li, Jun-Qing; Jin, Gen-Ming

    2016-01-01

    Within the framework of the dinuclear system model, production cross sections of proton-rich nuclei with charged numbers of Z=84-90 are investigated systematically. Possible combinations with the $^{28}$Si, $^{32}$S, $^{40}$Ar bombarding the target nuclides $^{165}$Ho, $^{169}$Tm, $^{170-174}$Yb, $^{175,176}$Lu, $^{174,176-180}$Hf and $^{181}$Ta are analyzed thoroughly. The optimal excitation energies and evaporation channels are proposed to produce the proton-rich nuclei. The systems are feasible to be constructed in experiments. It is found that the neutron shell closure of N=126 is of importance during the evaporation of neutrons. The experimental excitation functions in the $^{40}$Ar induced reactions can be nicely reproduced. The charged particle evaporation is comparable with neutrons in cooling the excited proton-rich nuclei, in particular for the channels with $\\alpha$ and proton evaporation. The production cross section increases with the mass asymmetry of colliding systems because of the decrease of...

  4. Mirror energy difference and the structure of loosely bound proton-rich nuclei around A = 20

    CERN Document Server

    Yuan, Cenxi; Xu, Furong; Suzuki, Toshio; Otsuka, Takaharu

    2014-01-01

    The properties of loosely bound proton-rich nuclei around A = 20 are investigated within the framework of nuclear shell model. In these nuclei, the strength of the effective interactions involving the loosely bound proton s1=2 orbit are significantly reduced in comparison with those in their mirror nuclei. We evaluate the reduction of the effective interaction by calculating the monopole-baseduniversal interaction (VMU) in the Woods-Saxon basis. The shell-model Hamiltonian in the sd shell, such as USD, can thus be modified to reproduce the binding energies and energy levels of the weakly bound proton-rich nuclei around A = 20. The effect of the reduction of the effective interaction on the structure and decay properties of these nuclei is also discussed.

  5. Nucleosynthesis of proton-rich nuclei. Experimental results on the rp-process

    Energy Technology Data Exchange (ETDEWEB)

    Galaviz, D [Centro de Fisica Nuclear da Universidade de Lisboa, 1070-325 Lisbon (Portugal); Amthor, A M; Bazin, D; Becerril, A D; Brown, B A; Cole, A; Cook, J M; Elliot, T; Estrade, A; Gade, A; Glasmacher, T; Lorusso, G; Matos, M; Montes, F; Mueller, W [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Chen, A A [Department of Physics and Astronomy, McMaster University, Hamilton, ON L8S 4M1 (Canada); Fueloep, Z S [ATOMKI, H-4001 Debrecen, POB. 51 (Hungary); Heger, A [Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, Michigan 48824 (United States); Howard, M E [Department of Physics, Ohio State University, Columbus, Ohio 43210 (United States); Kessler, R, E-mail: galaviz@cii.fc.ul.p [Institut fuer Kernchemie, University of Mainz, D-55128 Mainz (Germany)

    2010-01-01

    We report in this study the nuclear properties of proton-rich isotopes located along the rp-process path. The experiments have recently been performed at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. The level properties above the proton separation energy of the nuclei {sup 30}S, {sup 36}K and {sup 37}Ca were measured with precision of < 10 keV. This will allow a reduction in the determination of the astrophysical (p,{gamma}) reaction rate under rp-process conditions.

  6. Nucleosynthesis of proton-rich nuclei. Experimental results on the rp-process

    Science.gov (United States)

    Galaviz, D.; Amthor, A. M.; Bazin, D.; Becerril, A. D.; Brown, B. A.; Chen, A. A.; Cole, A.; Cook, J. M.; Elliot, T.; Estrade, A.; Fülöp, Z. S.; Gade, A.; Glasmacher, T.; Heger, A.; Howard, M. E.; Kessler, R.; Lorusso, G.; Matos, M.; Montes, F.; Müller, W.; Pereira, J.; Schatz, H.; Sherrill, B.; Schertz, F.; Shimbara, Y.; Smith, E.; Smith, K.; Tamii, A.; Stolz, A.; Weisshaar, D.; Wallace, M.; Wiescher, M.; Zegers, R. G. T.

    2010-01-01

    We report in this study the nuclear properties of proton-rich isotopes located along the rp-process path. The experiments have recently been performed at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. The level properties above the proton separation energy of the nuclei 30S, 36K and 37Ca were measured with precision of < 10 keV. This will allow a reduction in the determination of the astrophysical (p,γ) reaction rate under rp-process conditions.

  7. Exotic octupole deformation in proton-rich Z=N nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Takami, Satoshi; Yabana, K. [Niigata Univ. (Japan); Matsuo, M.

    1998-03-01

    We study static non-axial octupole deformations in proton-rich Z=N nuclei, {sup 64}Ge, {sup 68}Se, {sup 72}Kr, {sup 76}Sr, {sup 80}Zr and {sup 84}Mo, by using the Skyrme Hartree-Fock plus BCS method with no restrictions on the nuclear shape. The calculation predicts that the oblate ground state in {sup 68}Se is extremely soft for the Y{sub 33} triangular deformation, and that in {sup 80}Zr the low-lying local minimum state coexisting with the prolate ground state has the Y{sub 32} tetrahedral deformation. (author)

  8. Study of the Beta-Decay Properties of Extremely Proton-Rich Nuclei

    CERN Multimedia

    2002-01-01

    The most proton-rich nuclei known to date have isospin projections $ T _{Z} $ ~=~-3/2, -2 and -5/2. \\\\ \\\\ We propose to carry out a study of their superallowed beta decays, a phenomenon that can only be studied in this region of the nuclear chart. The main aim is to determine the ``effective charge'' in nuclei of the axial vector coupling, the quantity $ ( g'_{A} / g _{A} ) ^{2} $ , which in a recent first experiment on a ~~ $ T _{Z} $~~=~-2 nucleus was determined to be 0.49~$\\pm$~0.05. \\\\ \\\\ Because of the problems connected with the production and acceleration of radioactive ions, our proposal aims at selected elements: neon, argon and rubidium (production runs), magnesium (test and production runs) and calcium (test). Data have so far been taken for $^1

  9. Proton rich nuclei at and beyond the proton drip line in the Relativistic Mean Field theory

    CERN Document Server

    Geng, L S; Meng, J

    2003-01-01

    The Relativistic Mean Field theory is applied to the analysis of ground-state properties of deformed proton-rich odd-Z nuclei in the region $55\\le Z \\le 73$ >. The model uses the TMA and NL3 effective interactions in the mean-field Lagrangian, and describes pairing correlations by the density-independent delta-function interaction. The model predicts the location of the proton drip line, the ground-state quadrupole deformation, one-proton separation energy at and beyond the proton drip line, the deformed single-particle orbital occupied by the odd valence proton and the corresponding spectroscopic factor. The results are in good agreement with the available experimental data except for some odd-odd nuclei in which the proton-neutron pairing may become important and are close to those of Relativistic Hartree-Bogoliubov model.

  10. Measurement of reaction cross section for proton-rich nuclei (A<30) at intermediate energies

    CERN Document Server

    Zhang, H Y; Ren Zhong Zhou; Ma, Y G; Jiang, W Z; Zhu, Z Y; Cai, X Z; Fang, D Q; Zhong, C; Yu Li Ping; Wei, Y B; Zhan, W L; Guo, Z Y; Xiao, G Q; Wang, J S; Wang, J C; Wang, Q J; Li, J X; Wang, M; Chen, Z Q

    2002-01-01

    Radioactive ion beams were produced through the projectile fragmentation induced by 69 MeV/ nucleon sup 3 sup 6 Ar primary beam on a sup 9 Be target. Measurements of reaction cross sections (sigma sub R 's) for 44 nuclei with A<30 (mostly proton-rich), on carbon were performed on RIBLL (Radioactive Ion Beam Line in Lanzhou) of HIRFL (Heavy Ion Research Facility in Lanzhou) at intermediate energies around 30 MeV/nucleon by a transmission method. The experimental sigma sub R values for sup 2 sup 3 Al and sup 2 sup 7 P are abnormally large compared with their neighboring nuclei. Together with the previous experimental facts such as the binding energy and ground state data, it suggests anomalously large matter root-mean-square radii and proton halo structure in sup 2 sup 3 Al and in sup 2 sup 7 P. There is an enhancement for the sigma sub R of sup 1 sup 7 F + sup 1 sup 2 C compared with the neighboring isotopes. Considering that the ground state of sup 1 sup 7 F is 1d sub 5 sub / sub 2 , this can indicate that...

  11. Investigations of charge-changing processes for light proton-rich nuclei on carbon and solid-hydrogen targets

    Energy Technology Data Exchange (ETDEWEB)

    Sawahata, K. [Institute of Physics, University of Tsukuba, Ibaraki 305-8571 (Japan); Ozawa, A., E-mail: ozawa@tac.tsukuba.ac.jp [Institute of Physics, University of Tsukuba, Ibaraki 305-8571 (Japan); Saito, Y.; Abe, Y.; Ichikawa, Y.; Inaba, N.; Ishibashi, Y. [Institute of Physics, University of Tsukuba, Ibaraki 305-8571 (Japan); Kitagawa, A. [National Institute of Radiological Sciences, Chiba 263-8555 (Japan); Matsunaga, S. [Department of Physics, Saitama University, Saitama 338-8570 (Japan); Moriguchi, T.; Nagae, D.; Okada, S. [Institute of Physics, University of Tsukuba, Ibaraki 305-8571 (Japan); Sato, S. [National Institute of Radiological Sciences, Chiba 263-8555 (Japan); Suzuki, S. [Institute of Physics, University of Tsukuba, Ibaraki 305-8571 (Japan); Suzuki, T.; Takeuchi, Y.; Yamaguchi, T. [Department of Physics, Saitama University, Saitama 338-8570 (Japan); Zenihiro, J. [RIKEN Nishina Center, Wako, Saitama 351-0198 (Japan)

    2017-05-15

    We investigated charge-changing processes (total charge-changing cross sections and partial charge-changing cross sections) for light proton-rich nuclei ({sup 34–36}Ar, {sup 33}Cl, {sup 25–28}Si) at around 300A MeV on carbon and solid-hydrogen targets. We estimated the nuclear proton point radii of {sup 33}Cl and {sup 25,26,27}Si from the observed total charge-changing cross sections by using Glauber-model calculations with a phenomenological correction factor. Furthermore, we estimated the proton skin thickness for {sup 33}Cl coupled with its previously observed matter radius. From investigations of the partial charge-changing cross sections, clear zigzag pattern was observed for all isotopes. The present studies suggest that the pattern may be common in the proton-rich side, and depends on the odd–even nature of the fragment charge.

  12. Isotopic excesses of proton-rich nuclei related to space weathering observed in a gas-rich meteorite Kapoeta

    Energy Technology Data Exchange (ETDEWEB)

    Hidaka, Hiroshi [Department of Earth and Planetary Systems Science, Hiroshima University, Higashi-Hiroshima 739-8526 (Japan); Yoneda, Shigekazu, E-mail: hidaka@hiroshima-u.ac.jp, E-mail: s-yoneda@kahaku.go.jp [Department of Science and Engineering, National Museum of Nature and Science, Tsukuba 305-0005 (Japan)

    2014-05-10

    The idea that solar system materials were irradiated by solar cosmic rays from the early Sun has long been suggested, but is still questionable. In this study, Sr, Ba, Ce, Nd, Sm, and Gd isotopic compositions of sequential acid leachates from the Kapoeta meteorite (howardite) were determined to find systematic and correlated variations in their isotopic abundances of proton-rich nuclei, leading to an understanding of the irradiation condition by cosmic rays. Significantly large excesses of proton-rich isotopes (p-isotopes), {sup 84}Sr, {sup 130}Ba, {sup 132}Ba, {sup 136}Ce, {sup 138}Ce, and {sup 144}Sm, were observed, particularly in the first chemical separate, which possibly leached out of the very shallow layer within a few μm from the surface of regolith grains in the sample. The results reveal the production of p-isotopes through the interaction of solar cosmic rays with the superficial region of the regolith grains before the formation of the Kapoeta meteorite parent body, suggesting strong activity in the early Sun.

  13. Different mechanism of two-proton emission from proton-rich nuclei $^{23}$Al and $^{22}$Mg

    CERN Document Server

    Ma, Y G; Sun, X Y; Zhou, P; Togano, Y; Aoi, N; Baba, H; Cai, X Z; Cao, X G; Chen, J G; Fu, Y; Guo, W; Hara, Y; Honda, T; Hu, Z G; Ieki, K; Ishibashi, Y; Ito, Y; Iwasa, N; Kanno, S; Kawabata, T; Kimura, H; Kondo, Y; Kurita, K; Kurokawa, M; Moriguchi, T; Murakami, H; Ooishi, H; Okada, K; Ota, S; Ozawa, A; Sakurai, H; Shimoura, S; Shioda, R; Takeshita, E; Takeuchi, S; Tian, W D; Wang, H W; Wang, J S; Wang, M; Yamada, K; Yamada, Y; Yasuda, Y; Yoneda, K; Zhang, G Q; Motobayashi, T

    2015-01-01

    Two-proton relative momentum ($q_{pp}$) and opening angle ($\\theta_{pp}$) distributions from the three-body decay of two excited proton-rich nuclei, namely $^{23}$Al $\\rightarrow$ p + p + $^{21}$Na and $^{22}$Mg $\\rightarrow$ p + p + $^{20}$Ne, have been measured with the projectile fragment separator (RIPS) at the RIKEN RI Beam Factory. An evident peak at $q_{pp}\\sim20$ MeV/c as well as a peak in $\\theta_{pp}$ around 30$^\\circ$ are seen in the two-proton break-up channel from a highly-excited $^{22}$Mg. In contrast, such peaks are absent for the $^{23}$Al case. It is concluded that the two-proton emission mechanism of excited $^{22}$Mg is quite different from the $^{23}$Al case, with the former having a favorable diproton emission component at a highly excited state and the latter dominated by the sequential decay process.

  14. Proton and Two-proton Emissions from Proton-rich Nuclei with 10 6 Z 6 20

    Institute of Scientific and Technical Information of China (English)

    林承键; 金仕纶; 黄美容; 白真; 吴振东; 杨峰; 胡正国; 王猛; 雷相国; 张焕乔; 徐瑚珊; 徐新星; 肖国青; 王建松; 孙立杰; 贾会明; 杨磊; 马朋; 马军兵; 杨彦云

    2016-01-01

    Proton (p) and two-proton (2p) emissions from the proton-rich nuclei with 10 6 Z 6 20 have been explored by the in-fight decay and implantation decay methods, respectively, in a series of experi-ments at the HIRFL-RIBLL facility. The in-flight 2p emissions from the excited states of 28,29S/26,27P and 17,18Ne were studied by complete-kinematics measurements. Mechanisms of 2p decay and related p-p correlations have been explored. Obvious 2p correlated emissions have been observed in the cases of 28,29S but not in 27,28P, indicating the 2p halo plays an important role in the diproton emission. In the 17,18Ne cases, a small 2p opening angles were deduced by the HBT analyses, implying the BCS-BEC crossover may occur in the dilute nuclear matter. Moreover, 27S/26P/25Si, 22Si/20Mg, 23Si/22Al/21Mg, 24Si/23Al, and 36,37Ca were implanted in a thin double-sided-silicon-strip detector and their β-delayed p and 2p decays have been measured by a surrounding silicon detector array under the continuous-beam mode. Important information on the nuclear spectroscopy, such as energy, lifetime, branching-ratio, and so on, has been extracted, which helps us to understand the nuclear structures of proton-rich exotic nuclei close to the drip-line.

  15. Theoretical studies of proton capture reactions in A~25 proton-rich nuclei

    Institute of Scientific and Technical Information of China (English)

    QI Chong; DU RenZhong; GAO Yang; ZHU JianYu; XU FuRong

    2009-01-01

    The direct proton capture and resonance proton capture properties of stellar reactions 22Mg(p,γ)23Aland 25Si(p,γ)27P are studied by employing a mean-field potential obtained from the Skyrme-Hartree-Fock (SHF) model.Calculations with the SHF potential reproduce well the loosely-bound structure of the ground states as well as the widths of the resonant states in these nuclei.With the obtained potential we estimate the reaction rates of direct proton capture and resonance proton capture to nuclei 23Al and 27p.The effect of the 27p loosely-bound structure on the S factor of the direct proton capture is also discussed.

  16. Theoretical studies of proton capture reactions in A~25 proton-rich nuclei

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The direct proton capture and resonance proton capture properties of stellar reactions 22Mg(p,γ)23Al and 26Si(p,γ)27P are studied by employing a mean-field potential obtained from the Skyrme-Hartree-Fock(SHF) model.Calculations with the SHF potential reproduce well the loosely-bound structure of the ground states as well as the widths of the resonant states in these nuclei.With the obtained potential we estimate the reaction rates of direct proton capture and resonance proton capture to nuclei 23Al and 27P.The effect of the 27P loosely-bound structure on the S factor of the direct proton capture is also discussed.

  17. $\\beta$-delayed fission in proton-rich nuclei in the lead region

    CERN Document Server

    AUTHOR|(CDS)2085005; Huyse, Mark; Popescu, Lucia

    Nuclear fission is the breakup of an atomic nucleus into two (sometimes three) fragments, thereby releasing a large amount of energy. Soon after its discovery in the late 1930’s, the gross properties of the fission phenomenon were explained by macroscopic nuclear models. Certain features however, such as asymmetric fission-fragment mass distributions in the actinide region, require the inclusion of microscopic effects. This interplay of the microscopic motion of individual nucleons on this macroscopic process is, until today, not yet fully understood. The phenomenon of fission has therefore been of recurring interest for both theoretical and experimental studies. This thesis work focuses on the $\\beta$-delayed fission ($\\beta$DF) process, an excellent tool to study low-energy fission of exotic nuclei, which was discovered in 1966 in the actinide region. In this two-step process, a precursor nucleus first undergoes $\\beta$-decay to an excited level in the daughter nucleus, which may subsequently fission. Rec...

  18. Conversion electron spectroscopy at the FMA focal plane: Decay studies of proton-rich N {approximately} 82 nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Nisius, D.; Janssens, R.V.F.; Ahmad, I. [and others

    1995-08-01

    The FMA has proven to be an ideal instrument for the detailed study of the decay of microsecond isomers behind the focal plane following mass selection. In reactions leading to the population of nuclei with isomeric lifetimes longer than their flight time through the device, decay gamma rays and conversion electrons can be detected in an environment free from the backgrounds of prompt radiation and delta electrons. This was a very successful technique to study proton (h{sub 11/2}){sup n} seniority isomers in nuclei with Z > 64 and N {approximately} 82. Since isomeric decay gamma rays are emitted isotropically, conversion electrons are essential for the assignment of multipolarities in these nuclei. Furthermore, the low-energy transitions that depopulate isomeric states are typically highly converted and can escape gamma-ray detection, but they can be identified by their conversion electrons.

  19. Systematic study of the isotopic dependence of fusion dynamics for neutron- and proton-rich nuclei using a proximity formalism

    CERN Document Server

    Ghodsi, O N; Lari, F

    2016-01-01

    The behaviors of barrier characteristics and fusion cross sections are analyzed by changing neutron over wide range of colliding systems. For this purpose, we have extended our previous study (Eur. Phys. J. A \\textbf{48}, 21 (2012), it is devoted to the colliding systems with neutron-rich nuclei) to 125 isotopic systems with condition of $0.5\\leq N/Z \\leq 1.6$ for their compound nuclei. The AW 95, Bass 80, Denisov DP and Prox. 2010 potentials are used to calculate the nuclear part of interacting potential. The obtained results show that the trend of barrier heights $V_B$ and positions $R_B$ as well as nuclear $V_N$ and Coulomb $V_C$ potentials (at $R=R_B$) as a function of ($N/Z-1$) quantity are non-linear (second-order) whereas the fusion cross sections follow a linear-dependence.

  20. Beta Decay of the Proton-Rich Nuclei 102Sn and 104Sn

    Energy Technology Data Exchange (ETDEWEB)

    Karny, M. [University of Warsaw; Batist, L. [St. Petersburg Nuclear Physics Institute; Banu, A. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Becker, F. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Blazhev, A. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Brown, B. A. [Michigan State University, East Lansing; Bruchle, W. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Doring, J. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Faestermann, T. [Technische Universitat Munchen; Gorska, M. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Grawe, H. [GSI-Hemholtzzentrum fur Schwerionenforschung, Darmstadt, Germany; Janas, Z. [University of Warsaw; Jungclaus, A. [Universidad Autonoma de Madrid, Madrid; Kavatsyuk, M. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Kavatsyuk, O. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Kirchner, R. [Gesellschaft fur Schwerionenforschung (GSI), Germany; La Commara, M. [Universita Federico II and INFN Napoli; Mandal, S. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Mazzocchi, C. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Miernik, K. [University of Warsaw; Mukha, I. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Muralithar, S. [University of Warsaw; Plettner, C. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Plochocki, A. [University of Warsaw; Roeckl, E. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Romoli, M. [Universita Federico II and INFN Napoli; Rykaczewski, Krzysztof Piotr [ORNL; Schadel, M. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Schmidt, K. [University of Warsaw; Schwengner, R. [University of Warsaw; Zylicz, J. [University of Warsaw

    2006-01-01

    The {beta} decays of {sup 102}Sn and {sup 104}Sn were studied by using high-resolution germanium detectors as well as a Total Absorption Spectrometer (TAS). For {sup 104}Sn, with three new {beta}-delayed {gamma}-rays identified, the total Gamow-Teller strength (BGT) value of 2.7(3) was obtained. For {sup 102}Sn, the {gamma}-{gamma} coincidence data were collected for the first time, allowing us to considerably extend the decay scheme. This scheme was used to unfold the TAS data and to deduce a BGT value of 4.2(8) for this decay. This result is compared to shell model predictions, yielding a hindrance factor of 3.6(7) in agreement with those obtained previously for {sup 98}Cd and {sup 100}In. Together with the latter two, {sup 102}Sn completes the triplet of Z {le} 50, N {ge} 50 nuclei with two proton holes, one proton hole and one neutron particle, and two neutron particles with respect to the doubly magic {sup 100}Sn core.

  1. Spectroscopic study of proton-rich nuclei with 22 {<=} Z {<=} 28 and T{sub z} {<=} -3/2; Etude spectroscopique des noyaux riches en protons dans la region 22 {<=} Z {<=} 28 et T{sub z} {<=} -3/2

    Energy Technology Data Exchange (ETDEWEB)

    Dossat, C

    2004-12-15

    The proton-rich nuclei in the region 22 {<=} Z {<=} 28 and T{sub Z} {<=} -3/2 have been studied in detail between 1999 and 2002 in 3 experiments performed at GANIL: 23 isotopes were studied from Ti{sup 39} to Ni{sup 53}. For the first time, we have measured the half-live of V{sup 43}, Ni{sup 51} and Co{sup 51} - we got respectively T1/2 = (81.3 {+-} 5.1) ms, (24.1 {+-} 0.8) ms and (69.4 {+-} 2.7) ms - and improved the accuracy for many other nuclei. New excited levels and {gamma} transitions were identified via {beta}-p-{gamma} or {beta}-{gamma} correlations in different nuclei in this mass region and allowed us to establish partial decay schemes for different isotopes. The experimental results have been compared with different model predictions for {beta}-decay half-lives and the branching ratios to the isobaric states yielding thus a wealth of new nuclear structure information far from stability.

  2. $\\beta$-decay half-lives and nuclear structure of exotic proton-rich waiting point nuclei under $rp$-process conditions

    CERN Document Server

    Nabi, Jameel-Un

    2016-01-01

    We investigate even-even nuclei in the $A\\sim70$ mass region within the framework of the proton-neutron quasi-particle random phase approximation (\\mbox{pn-QRPA}) and the interacting boson model-1 (\\mbox{IBM-1}). Our work includes calculation of the energy spectra and the potential energy surfaces $V(\\beta,\\gamma)$ of Zn, Ge, Se, Kr and Sr nuclei with the same proton and neutron number, $N = Z$. The parametrization of the \\mbox{IBM-1} Hamiltonian was performed for the calculation of the energy levels in the ground state bands. Geometric shape of the nuclei was predicted by plotting the potential energy surfaces $V(\\beta,\\gamma)$ obtained from the \\mbox{IBM-1} Hamiltonian in the classical limit. The \\mbox{pn-QRPA} model was later used to compute half-lives of the neutron-deficient nuclei which were found to be in very good agreement with the measured ones. The \\mbox{pn-QRPA} model was also used to calculate the Gamow-Teller strength distributions and was found to be in decent agreement with the measured data. ...

  3. Improvements to the on-line mass separator, RAMA, and the beta-delayed charged-particle emission of proton-rich sd shell nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Ognibene, Theodore Joseph [Lawrence Berkeley National Lab., CA (United States). Nuclear Science Div.

    1996-03-01

    To overcome the extreme difficulties encountered in the experimental decay studies of proton drip line nuclei, several techniques have been utilized, including a helium-jet transport system, particle identification detectors and mass separation. Improvements to the ion source/extraction region of the He-jet coupled on-line Recoil Atom Mass Analyzer (RAMA) and its target/ion source coupling resulted in significant increases in RAMA efficiencies and its mass resolution, as well as reductions in the overall transit time. At the 88-Inch Cyclotron at LBNL, the decays of 31Cl, 27P and 28P, with half-lives of 150 msec, 260 msec and 270.3 msec, respectively, were examined using a he-jet and low-energy gas ΔE-gas ΔE-silicon E detector telescopes. Total beta-delayed proton branches of 0.3% and 0.07% in 31Cl and 27P, respectively, were estimated. Several proton peaks that had been previously assigned to the decay of 31Cl were shown to be from the decay of 25Si. In 27P, two proton groups at 459 ± 14 keV and 610 ± 11 keV, with intensities of 7 ± 3% and 92 ± 4% relative to the main (100%) group were discovered. The Gamow-Teller component of the preceding beta-decay of each observed proton transition was compared to results from shell model calculations. Finally, a new proton transition was identified, following the β-decay of 28P, at 1,444 ± 12 keV with a 1.7 ± 0.5% relative intensity to the 100% group. Using similar low-energy detector telescopes and the mass separator TISOL at TRIUMF, the 109 msec and 173 msec activities, 17Ne and 33Ar, were studied. A new proton group with energy 729 ± 15 keV was observed following the beta-decay of 17Ne. Several discrepancies between earlier works as to the energies, intensities and assignments of several proton transitions from 17Ne and 33Ar were resolved.

  4. Improvements to the on-line mass separator, RAMA, and the beta-delayed charged-particle emission of proton-rich sd shell nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Ognibene, T.J. [Lawrence Berkeley National Lab., CA (United States). Nuclear Science Div.

    1996-03-01

    To overcome the extreme difficulties encountered in the experimental decay studies of proton drip line nuclei, several techniques have been utilized, including a helium-jet transport system, particle identification detectors and mass separation. Improvements to the ion source/extraction region of the He-jet coupled on-line Recoil Atom Mass Analyzer (RAMA) and its target/ion source coupling resulted in significant increases in RAMA efficiencies and its mass resolution, as well as reductions in the overall transit time. At the 88-Inch Cyclotron at LBNL, the decays of {sup 31}Cl, {sup 27}P and {sup 28}P, with half-lives of 150 msec, 260 msec and 270.3 msec, respectively, were examined using a he-jet and low-energy gas {Delta}E-gas {Delta}E-silicon E detector telescopes. Total beta-delayed proton branches of 0.3% and 0.07% in {sup 31}Cl and {sub 27}P, respectively, were estimated. Several proton peaks that had been previously assigned to the decay of {sup 31}Cl were shown to be from the decay of {sup 25}Si. In {sup 27}P, two proton groups at 459 {+-} 14 keV and 610 {+-} 11 keV, with intensities of 7 {+-} 3% and 92 {+-} 4% relative to the main (100%) group were discovered. The Gamow-Teller component of the preceding beta-decay of each observed proton transition was compared to results from shell model calculations. Finally, a new proton transition was identified, following the {beta}-decay of {sup 28}P, at 1,444 {+-} 12 keV with a 1.7 {+-} 0.5% relative intensity to the 100% group. Using similar low-energy detector telescopes and the mass separator TISOL at TRIUMF, the 109 msec and 173 msec activities, {sup 17}Ne and {sup 33}Ar, were studied. A new proton group with energy 729 {+-} 15 keV was observed following the beta-decay of {sup 17}Ne. Several discrepancies between earlier works as to the energies, intensities and assignments of several proton transitions from {sup 17}Ne and {sup 33}Ar were resolved.

  5. The production of proton-rich isotopes beyond iron: The $\\gamma$ process in stars

    CERN Document Server

    Pignatari, Marco; Reifarth, René; Travaglio, Claudia

    2016-01-01

    Beyond iron, a small fraction of the total abundances in the Solar System is made of proton-rich isotopes, the p nuclei. The clear understanding of their production is a fundamental challenge for nuclear astrophysics. The p nuclei constrain the nucleosynthesis in core-collapse and thermonuclear supernovae. The $\\gamma$ process is the most established scenario for the production of the p nuclei, which are produced via different photodisintegration paths starting on heavier nuclei. A large effort from nuclear physics is needed to access the relevant nuclear reaction rates far from the valley of stability. This review describes the production of the heavy proton-rich isotopes by the $\\gamma$ process in stars, and explores the state of the art of experimental nuclear physics to provide nuclear data for stellar nucleosynthesis.

  6. New type of asymmetric fission in proton-rich nuclei

    CERN Document Server

    Andreyev, A N; Huyse, M; Van Duppen, P; Antalic, S; Barzakh, A; Bree, N; Cocolios, T E; Comas, V F; Diriken, J; Fedorov, D; Fedosseev, V; Franchoo, S; Heredia, J A; Ivanov, O; Koster, U; Marsh, B A; Nishio, K; Page, R D; Patronis, N; Seliverstov, M; Tsekhanovich, I; Van den Bergh, P; Van De Walle, J; Venhart, M; Vermote, S; Veselsky, M; Wagemans, C; Ichikawa, T; Iwamoto, A; Moller, P; Sierk, A J

    2010-01-01

    A very exotic process of ${\\beta}$-delayed fission of $^{180}$Tl is studied in detail by using resonant laser ionization with subsequent mass separation at ISOLDE (CERN). In contrast to common expectations, the fission-fragment mass distribution of the post-${\\beta}$-decay daughter nucleus $^{180}$Hg (N/Z=1.25) is asymmetric. This asymmetry is more surprising since a mass-symmetric split of this extremely neutron-deficient nucleus would lead to two $^{90}$Zr fragments, with magic N=50 and semimagic Z=40. This is a new type of asymmetric fission, not caused by large shell effects related to fragment magic proton and neutron numbers, as observed in the actinide region. The newly measured branching ratio for $\\beta$-delayed fission of $^{180}$Tl is 3.6(7)×10$^{-3}$%, approximately 2 orders of magnitude larger than in an earlier study.

  7. A Statistical Approach to Describe Highly Excited Heavy and Superheavy Nuclei

    CERN Document Server

    Chen, Peng-Hui; Li, Jun-Qing; Zhang, Hong-Fei

    2016-01-01

    A statistical approach based on the Weisskopf evaporation theory has been developed to describe the de-excitation process of highly excited heavy and superheavy nuclei, in particular for the proton-rich nuclei. The excited nucleus is cooled by evaporating $\\gamma$-ray, light particles (neutrons, protons, $\\alpha$ etc) in competition with the binary fission, in which the structure effects (shell correction, fission barrier, particle separation energy) contribute to the processes. The formation of residual nuclei is evaluated via sequential emission of possible particles above the separation energies. The available data of fusion-evaporation excitation functions in the $^{28}$Si+$^{198}$Pt reaction can be reproduced nicely well within the approach.

  8. Beta-decay in odd-A and even-even proton-rich Kr isotopes

    CERN Document Server

    Sarriguren, P; Escuderos, A

    2001-01-01

    Beta-decay properties of proton-rich odd-A and even-even Krypton isotopes are studied in the framework of a deformed selfconsistent Hartree-Fock calculation with density-dependent Skyrme forces, including pairing correlations between like nucleons in BCS approximation. Residual spin-isospin interactions are consistently included in the particle-hole and particle-particle channels and treated in Quasiparticle Random Phase Approximation. The similarities and differences in the treatment of even-even and odd-A nuclei are stressed. Comparison to available experimental information is done for Gamow-Teller strength distributions, summed strengths, and half-lives. The dependence of these observables on deformation is particularly emphasized in a search for signatures of the shape of the parent nucleus.

  9. Searching for high-K isomers in the proton-rich A ˜ 80 mass region

    Science.gov (United States)

    Bai, Zhi-Jun; Jiao, Chang-Feng; Gao, Yuan; Xu, Fu-Rong

    2016-09-01

    Configuration-constrained potential-energy-surface calculations have been performed to investigate the K isomerism in the proton-rich A ˜ 80 mass region. An abundance of high-K states are predicted. These high-K states arise from two and four-quasi-particle excitations, with Kπ = 8+ and Kπ = 16+, respectively. Their excitation energies are comparatively low, making them good candidates for long-lived isomers. Since most nuclei under study are prolate spheroids in their ground states, the oblate shapes of the predicted high-K states may indicate a combination of K isomerism and shape isomerism. Supported by National Key Basic Research Program of China (2013CB834402) and National Natural Science Foundation of China (11235001, 11320101004 and 11575007)

  10. Alpha radioactivity for proton-rich even Pb isotopes

    Indian Academy of Sciences (India)

    Arati Devi; S Prakash; I Mehrotra

    2009-04-01

    Half-lives for alpha radioactivity from proton-rich even Pb isotopes in the range = 182–202 have been calculated using the unified fission-like approach. The geometrical shape of the potential barrier is parametrized in terms of a highly versatile, asymmetric and analytically solvable form of potential based on Ginnochio’s potential. Good agreement with the experimental data has been obtained with the variation of just one parameter. Half-lives of three unknown alpha emitters in the neutron-deficient Pb chain (198Pb, 200Pb and 204Pb) have been predicted. The exact expression for the transmission coefficient has been compared with those obtained from WKB approximation method for symmetric Eckart potential.

  11. Polarization creation in proton-rich {sup 28}P via charge exchange reactions and measurement of its electric quadrupole moment

    Energy Technology Data Exchange (ETDEWEB)

    Matsuta, K., E-mail: matsuta@vg.phys.sci.osaka-u.ac.jp; Mihara, M. [Osaka University, Department of Physics (Japan); Zhou, D. M.; Zheng, Y. N. [CIAE (China); Nishimura, D. [Osaka University, Department of Physics (Japan); Nagatomo, T. [International Christian University (Japan); Yuan, D. Q. [CIAE (China); Momota, S. [Kochi University of Technology (Japan); Izumikawa, T. [Niigata University, RI Center (Japan); Zuo, Y.; Fan, P.; Zhu, S. Y. [CIAE (China); Ohtsubo, T. [Niigata University (Japan); Fukuda, M. [Osaka University, Department of Physics (Japan); Namiki, Y.; Nagashima, M. [Niigata University (Japan); Minamisono, T. [Fukui University of Technology (Japan); Kameda, D. [RIKEN (Japan); Sumikama, T. [Tokyo University of Science (Japan); Kitagawa, A. [NIRS (Japan); and others

    2010-06-15

    The degrees of polarization of proton rich nucleus {sup 28}P produced in charge exchange reactions {sup 28}Si + {sup 9}Be {yields} {sup 28}P + X, and {sup 28}Si + {sup 1}H {yields} {sup 28}P + X have been observed at 100A MeV. Utilizing thus obtained polarized nuclei, the magnetic moment of {sup 28}P was remeasured, and vertical bar {mu}({sup 28}P) vertical bar = 0.3115 (34) {mu}{sub N} was obtained. {beta}-nuclear quadrupole resonance ({beta}-NQR) of {sup 28}P implanted in {alpha}-Al{sub 2}O{sub 3} have been observed for the first time, in order to measure the electric quadrupole moment of this nucleus.

  12. A statistical approach to describe highly excited heavy and superheavy nuclei

    Science.gov (United States)

    Chen, Peng-Hui; Feng, Zhao-Qing; Li, Jun-Qing; Zhang, Hong-Fei

    2016-09-01

    A statistical approach based on the Weisskopf evaporation theory has been developed to describe the de-excitation process of highly excited heavy and superheavy nuclei, in particular for the proton-rich nuclei. The excited nucleus is cooled by evaporating γ-rays, light particles (neutrons, protons, α etc) in competition with binary fission, in which the structure effects (shell correction, fission barrier, particle separation energy) contribute to the processes. The formation of residual nuclei is evaluated via sequential emission of possible particles above the separation energies. The available data of fusion-evaporation excitation functions in the 28Si+198Pt reaction can be reproduced nicely within the approach. Supported by Major State Basic Research Development Program in China (2015CB856903), National Natural Science Foundation of China Projects (11175218, U1332207, 11475050, 11175074), and Youth Innovation Promotion Association of Chinese Academy of Sciences

  13. A relationship between halo mass, cooling, active galactic nuclei heating and the co-evolution of massive black holes

    Science.gov (United States)

    Main, R. A.; McNamara, B. R.; Nulsen, P. E. J.; Russell, H. R.; Vantyghem, A. N.

    2017-02-01

    We derive X-ray mass, luminosity, and temperature profiles for 45 galaxy clusters to explore relationships between halo mass, active galactic nuclei (AGN) feedback, and central cooling time. We find that radio-mechanical feedback power (referred to here as `AGN power') in central cluster galaxies correlates with halo mass as Pmech ∝ M1.55 ± 0.26, but only in haloes with central atmospheric cooling times shorter than 1 Gyr. The trend of AGN power with halo mass is consistent with the scaling expected from a self-regulating AGN feedback loop, as well as with galaxy and central black hole co-evolution along the MBH-σ relation. AGN power in clusters with central atmospheric cooling times longer than ˜1 Gyr typically lies two orders of magnitude below those with shorter central cooling times. Galaxies centred in clusters with long central cooling times nevertheless experience ongoing and occasionally powerful AGN outbursts. We further investigate the impact of feedback on cluster scaling relations. We find L-T and M-T relations in clusters with direct evidence of feedback which are steeper than self-similar, but not atypical compared to previous studies of the full cluster population. While the gas mass rises, the stellar mass remains nearly constant with rising total mass, consistent with earlier studies. This trend is found regardless of central cooling time, implying tight regulation of star formation in central galaxies as their haloes grew, and long-term balance between AGN heating and atmospheric cooling. Our scaling relations are presented in forms that can be incorporated easily into galaxy evolution models.

  14. Hot Bubbles from Active Galactic Nuclei as a Heat Source in Cooling Flow Clusters

    CERN Document Server

    Brüggen, M; Brueggen, Marcus; Kaiser, Christian R.

    2002-01-01

    The hot plasma permeating clusters of galaxies often shows a central peak in the X-ray surface brightness that is coincident with a drop in entropy. This is taken as evidence for a cooling flow where the radiative cooling in the central regions of a cluster causes a slow subsonic inflow. Searches in all wavebands have revealed significantly less cool gas than predicted indicating that the mass deposition rate of cooling flows is much lower than expected. However, most cooling flow clusters host an Active Galactic Nucleus (AGN) at their centres. AGN can inflate large bubbles of hot plasma that subsequently rise through the cluster atmosphere, thus stirring this gas. Here we report on the results from highly resolved hydrodynamic simulations which for the first time show that buoyant bubbles increase the cooling time in the inner cluster regions and thereby significantly reduce the deposition of cold gas. This work demonstrates that the action of AGN in the centres of cooling flow clusters can explain the obser...

  15. Magnetic Moment and Spin of the Extremely Proton-Rich Nucleus {sup 23}Al

    Energy Technology Data Exchange (ETDEWEB)

    Matsuta, K., E-mail: matsuta@vg.phys.sci.osaka-u.ac.jp; Nakashima, Y.; Nagatomo, T.; Mihara, M.; Kumashiro, S.; Fujiwara, H.; Ogura, M.; Fukuda, M.; Minamisono, T. [Osaka University, Department of Physics (Japan); Sumikama, T. [RIKEN (Japan); Ozawa, A. [University of Tsukuba, Institute of Physics (Japan); Yamada, K. [Rikkyo University, College of Science (Japan); Momota, S.; Nojiri, Y. [Tosayamada, Kochi University of Technology (Japan); Ota, M.; Ohtsubo, T.; Izumikawa, T. [Niigata University, Department of Physics (Japan); Yoshida, K. [RIKEN (Japan); Minamisono, K. [TRIUMF (Canada); Suzuki, T. [Saitama University, Department of Physics (Japan)

    2004-12-15

    The g-factor of the exteremely proton-rich nucleus {sup 23}Al(T{sub 1/2} 0.47 s) has been measured for the first time, applying {beta}-NMR technique on this nucleus implanted in Si. The obtained vertical bar g vertical bar (1.58 {+-} 0.2) suggests that the spin of the ground state of {sup 23}Al is 5 / 2. The magnetic moment is determined as vertical bar {mu} vertical bar (3.95 {+-} 0.55) {mu}{sub N}.

  16. Shell structure of nuclei far from stability

    CERN Document Server

    Grawe, H

    2001-01-01

    The experimental status of shell structure studies in medium-heavy nuclei far off the line of beta-stability is reviewed. Experimental techniques, signatures for shell closure and expectations for future investigations are discussed for the key regions around sup 4 sup 8 sup , sup 5 sup 6 Ni, sup 1 sup 0 sup 0 Sn for proton rich nuclei and the neutron-rich N=20 isotones, Ca, Ni and Sn isotopes.

  17. Nuclear structure of proton-rich unstable nucleus 28P studied by g-factor measurement*

    Institute of Scientific and Technical Information of China (English)

    ZHENG Yong-Nan; ZHOU Dong-Mei; K. Matsuta; M. Mihara; M. Fukuda; D. Nishimura; J. Komurasaki; D. Ishikawa; R. Matsumiya; T. Nagatomo; T. Izumikawa; S. Takahashi; H. Hirano; T. Ohtsubo; S. Momota; Y. Nojiri; A. Kitagawa; M. Kanazawa; M. Torikoshi; S. Sato; T. Minamisono; J.R. Alonso; G.F. Krebs; T. J. M. Symons; YUAN Da-Qing; ZUO Yi; FAN Ping; T. Suzuki; ZHANG Xi-Zhen; ZHU Sheng-Yun

    2009-01-01

    Nuclear structure of proton-rich unstable nucleus 28P has been studied by measuring its g-factor for the first time. The g-factor of 28P (Iπ =3+, T1/2=270.3 ms) was measured by means of β-NMR technique combined with the new polarization technique for charge exchange reaction product in the intermediate energy heavy ion collisions. The obtained g-factor of g=0.1028(27) is very much quenched from the Schmidt value,but is well reproduced by the shell model (+0.102). In connection with the magnetic moment of the mirror partner and the β-ray transition probability, the orbital angular momenta and intrinsic spins of protons and neutrons have been determined as 〈lp〉 = 0.43(29), 〈ln〉 = 1.85(29), 〈Sp〉 = 0.28(4), and 〈Sn〉 = 0.44(4).

  18. Precise nuclear moments of extremely proton-rich nuclus {sup 23}Al

    Energy Technology Data Exchange (ETDEWEB)

    Nagatomo, T., E-mail: nagatomo@riken.jp [International Christian University (Japan); Ueno, H. [RIKEN Nishina Center (Japan); Mihara, M.; Matsuta, K. [Osaka University (Japan); Yoshimi, A.; Ichikawa, Y.; Yamada, K.; Kawamura, H. [RIKEN Nishina Center (Japan); Ozawa, A.; Moriguchi, T.; Ishibashi, Y. [University of Tsukuba (Japan); Asahi, K.; Uchida, M.; Suzuki, K.; Inoue, T.; Hasama, Y.; Iijima, H. [Tokyo Institute of Technology (Japan); Sumikama, T. [Tokyo University of Science (Japan); Fukuda, M. [Osaka University (Japan); Minamisono, T. [Fukui University of Technology (Japan)

    2010-06-15

    Electric quadrupole coupling constant eqQ/h of the extremely proton-rich {sup 23}Al (I{sup {pi}} = 5/2{sup + }, T{sub 1/2} = 0.47 s) nucleus implanted into an Al{sub 2}O{sub 3} single crystal has been measured for the first time, using the {beta}-ray detecting nuclear quadrupole resonance method ({beta}-NQR) in a high magnetic field. As a preliminary result, the quadrupole coupling constant was determined as vertical bar eqQ/h({sup 23}Al) vertical bar = 2.66{+-}0.77 MHz. Using the quadrupole coupling constant of {sup 27}Al in Al{sub 2}O{sub 3} as a reference, the Q moment of the ground state of {sup 23}Al was extracted as vertical bar Q({sup 23}Al) vertical bar {approx} 160 mb, which is well explained by the shell model calculation in the sd-shell model space with the USD interaction.

  19. Neutron and Alpha Structure in Neutron Deficient Nuclei in Astrophysics

    Institute of Scientific and Technical Information of China (English)

    S. Kubono; T. Hashimoto; Y. Wakabayashi; N. Iwasa; S. Kato; T. Komatsubara; D. N. Binh; L. H. Khiem; N. N. Duy; T. Kawabata; C. Spitaleri; 何建军; G. G. Rapisarda; M. La Cognata; L. Lamia; R. G. Pizzone; S. Romano; A. Coc; N. de Sereville; F. Hammache; G. Kiss; S. Bishop; H. Yamaguchi; D. M. Kahl; S. Hayakawa; T. Teranishi; S. Cheribini; M. Gulino; Y. K. Kwon

    2016-01-01

    The paper includes discussions on the important role of neutron and alpha configurations in proton-rich nuclei in nuclear astrophysics in terms of nucleosynthesis under extremely high-temperature hydrogenburning conditions. The νp-process, which is supposed to take place at the very early epoch of type II supernovae, has considerable neutrons and alphas together with protons. The alpha-induced reactions on proton-rich unstable nuclei in the light mass regions is expected to play a crucial role, but very few of them were investigated well yet because of the experimental difficulties. Specifically, I report our recent experimental effort for the breakout process from the pp-chain region, 7Be(α,γ)11C(α,p)14N under the νp-process. The neutron-induced reactions on proton-rich nuclei, which is even more a challenging subject, were investigated previously for very few nuclei. One possible experimental method is the Trojan Horse Method (THM). We successfully have applied THM to the 18F(n,α)14N reaction study with an unstable beam of 18F.

  20. Microscopic calculation for α and heavier cluster emissions from proton rich Ba and Ce isotopes

    Science.gov (United States)

    Florescu, A.; Insolia, A.

    1995-08-01

    We present a completely microscopic approach for obtaining the preformation factors and the decay widths of α, 12Ca, and 16O cluster decays. We start from realistic single particle Woods-Saxon wave functions and include a large space BCS-type configuration mixing. A pairing interaction acting among valence particles, placed above a double magic core, was considered. The penetrability is evaluated within the WKB approximation. The model predictions are also checked for some well-known α and 14C decays from even-even nuclei.

  1. $\\beta$- decay of the proton-rich T$_{z} = -1/2$ nucleus, $^{71}$Kr

    CERN Document Server

    Oinonen, M; Äystö, J; Baumann, P; Didierjean, François; Honkanen, J A; Huck, A; Huyse, M; Knipper, A; Marguier, G; Novikov, Yu N; Popov, A; Ramdhane, M; Seliverstov, D M; Van Duppen, P; Walter, G

    1997-01-01

    $\\beta$- decay of the T$_{z}$ = - 1/2 nuclide $^{71}$Kr has been studied at the ISOLDE PSB Facility at CERN. $^{71}$Kr ions were produced in spallation reactions in a Nb foil using the 1 GeV proton beam and studied by means of $\\beta$-delayed proton, $\\beta$- and $\\gamma$-ray spectroscopy. The half-life and the $\\beta$-decay energy of $^{71}$Kr were determined using the decay of protons and positrons. These results: T$_{1/2}$ = 100 ± 3 ms and $Q_\\textrm{EC}$ = 10$^{14}$ ± 0.32 MeV and the first observation of the b-branch to the 207 keV level in $^{71}$Br makes the extension of the systematics of Gamow-Teller matrix elements of mirror nuclei up to A = 71 possible. Gamow-Teller strength of the same magnitude as that of the $fp$-shell mirror nuclei is observed for the ground state transition.

  2. Collective Multipole excitations of exotic nuclei in relativistic continuum random phase approximation

    CERN Document Server

    Yang, Ding; Ma, Zhongyu

    2013-01-01

    Journal of Combinatorial Theory, Series B, 98(1):173-225, 2008n exotic nuclei are studied in the framework of a fully self-consistent relativistic continuum random phase approximation (RCRPA). In this method the contribution of the continuum spectrum to nuclear excitations is treated exactly by the single particle Green's function. Different from the cases in stable nuclei, there are strong low-energy excitations in neutron-rich nuclei and proton-rich nuclei. The neutron or proton excess pushes the centroid of the strength function to lower energies and increases the fragmentation of the strength distribution. The effect of treating the contribution of continuum exactly are also discussed.

  3. Identification of Highly Deformed Even-Even Nuclides in the Neutron- and Proton-Rich Regions of the Nuclear Chart from the B(E2) and E2 Predictions in the Generalized Differential Equation Model

    CERN Document Server

    Nayak, R C

    2015-01-01

    We identify here possible occurrence of large deformations in the neutron- and proton-rich regions of the nuclear chart from extensive predictions of the values of the reduced quadrupole transition probability B-E2 for the transition from the ground state to the first 2+ state and the corresponding excitation energy E2 of even-even nuclei in the recently developed Generalized Differential Equation model exclusively meant for these physical quantities. This is made possible from our analysis of the predicted values of these two physical quantities and the corresponding deformation parameters derived from them such as the quadrupole deformation beta-2, the ratio of beta-2 to the Weisskopf single-particle beta-2 and the intrinsic electric quadruplole moment , calculated for a large number of both known as well as hitherto unknown even-even isotopes of Oxygen to Fermium (Z=8 to 100). Our critical analysis of the resulting data convincingly support possible existence of large collectivity for the nuclides 30,32 Ne...

  4. Studies of exotic nuclei; Etudes des noyaux exotiques

    Energy Technology Data Exchange (ETDEWEB)

    Angelique, J.C.; Orr, N.A. [Lab. de Physique Corpusculaire, Caen Univ., 14 (France); Collaboratio: CATANE (Italy), DAPNIA-Saclay, CSNSM-Orsay, GANIL-Caen, IPN-Orsay, NSCL-MSU (USA), Los Alamos (USA), University of Manchester (United Kingdom), University of Surrey (United Kingdom), FLNR JINR Dubna (Russia), IAP-Bucharest (Romania), NPI-Rez (Czech Republic), CCLRLC-Daresbury (United Kingdom)

    1997-12-31

    The study of the nuclei far off stability valley is of much interest for testing the nuclear models established for the stable nuclei but also for astrophysics to understand the nucleosynthesis. Experiments aim to measure the mass and lifetime, to build the decay schemes and also to study the structure and the properties of these nuclei. The radioactive beam group focused its research on light neutron-rich nuclei having a halo neutron structure. Mass measurements in N {approx} Z nuclei namely in A {approx} 60-80 proton-rich nuclei, important for understanding the rp process, are mentioned, as well as in nuclei in the {sup 100}Sn region. In the newly obtained {sup 26}O and {sup 28}O nuclei the lifetimes, the probabilities of emission of one for more neutrons were determined. The data analysis has permitted to determine also for the first time the lifetimes of {sup 27,29}F and {sup 30}Ne. Studies of nuclei in the {sup 100}Sn region, near the proton drip line in the ground and isomeric states are now under way. The spectroscopy (energy levels, gamma emissions, etc.) of the neutron-rich nuclei produced by the {sup 36}S fragmentation has been carried out in {sup 31}Ne, {sup 17}B and {sup 29}F. Studies by Coulomb excitation of the 2{sup +} excited states and associated probability B (E2) in O, Ne, Ni and Zn are now analysed 6 refs.

  5. {beta} decay of the proton-rich T{sub z}={minus}1/2 nucleus, {sup 71}Kr

    Energy Technology Data Exchange (ETDEWEB)

    Oinonen, M.; Aeystoe, J.; Honkanen, A. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, FIN-40351, Jyvaeskylae (Finland); Jokinen, A.; Aeystoe, J. [CERN, PPE Division, CH-1211 Geneva 23 (Switzerland); Baumann, P.; Didierjean, F.; Huck, A.; Knipper, A.; Ramdhane, M.; Walter, G. [CRN, CNRS-IN2P3, Universite Louis Pasteur, B.P. 28, F-67037 Strasbourg (France); Huyse, M.; Van Duppen, P. [Instituut voor Kern-en Stralingsfysica, University of Leuve n, Celestijnenlaan 200 D, B-3001 Leuven (Belgium); Marguier, G. [IPN, CNRS-IN2P3, Universite Claude Bernard, F-69622 Villeurb anne (France); Novikov, Y.; Popov, A.; Seliverstov, D.M. [St. Petersburg Nuclear Physics Institute, Gatchina, 188350 St. Pete rsburg, Russia] [CERN, CH-1211 Geneva 23 (Switzerland)

    1997-08-01

    {beta} decay of the T{sub z}={minus}1/2 nuclide {sup 71}Kr has been studied at the ISOLDE PSB Facility at CERN. {sup 71}Kr ions were produced in spallation reactions in a Nb foil using the 1 GeV proton beam and studied by means of {beta}-delayed proton, {beta}- and {gamma}-ray spectroscopy. The half-life and the {beta}-decay energy of {sup 71}Kr were determined using the decay of protons and positrons. These results: T{sub 1/2}=100{plus_minus}3ms and Q{sub EC}=10.14{plus_minus}0.32MeV and the first observation of the {beta} branch to the 207 keV level in {sup 71}Br makes the extension of the systematics of Gamow-Teller matrix elements of mirror nuclei up to A=71 possible. The Gamow-Teller strength of the same magnitude as that of the fp-shell mirror nuclei is observed for the ground-state transition. {copyright} {ital 1997} {ital The American Physical Society}

  6. Alpha decay as a probe for the structure of neutron-deficient nuclei

    CERN Document Server

    Qi, Chong

    2016-01-01

    The advent of radioactive ion beam facilities and new detector technologies have opened up new possibilities to investigate the radioactive decays of highly unstable nuclei, in particular the proton emission, $\\alpha$ decay and heavy cluster decays from neutron-deficient (or proton-rich) nuclei around the proton drip line. It turns out that these decay measurements can serve as a unique probe for studying the structure of the nuclei involved. On the theoretical side, the development in nuclear many-body theories and supercomputing facilities have also made it possible to simulate the nuclear clusterization and decays from a microscopic and consistent perspective. In this article we would like to review the current status of these structure and decay studies in heavy nuclei, regarding both experimental and theoretical opportunities. We then discuss in detail the recent progress in our understanding of the nuclear $\\alpha$ formation probabilities in heavy nuclei and their indication on the underlying nuclear st...

  7. Superheavy nuclei

    CERN Document Server

    Sáro, S

    2003-01-01

    Experiments leading to transuranium and far transuranium nuclei as far as element 106 (seaborgium) are described. Physical knowledge derived from experimental data at this stage of complete synthesis nuclear reactions since the 1980s is analyzed. The effect of the shell structure on the stability of the nuclei, the extra-push effect, and the effect of isospin are discussed. Experiments leading to the synthesis of nuclei with Z = 107 - 112 by cold fusion are also described, as are hot fusion reactions resulting in superheavy nuclei Z = 114, 116 where, however, confirmation is only pending. Current state of the art in this area is also highlighted

  8. Isospin-symmetry-breaking effects in A∼70 nuclei within beyond-mean-field approach

    Energy Technology Data Exchange (ETDEWEB)

    Petrovici, A.; Andrei, O. [National Institute for Physics and Nuclear Engineering, R-077125 Bucharest (Romania)

    2015-02-24

    Particular isospin-symmetry-breaking probes including Coulomb energy differences (CED), mirror energy differences (MED), and triplet energy differences (TED) manifest anomalies in the A∼70 isovector triplets of nuclei. The structure of proton-rich nuclei in the A∼70 mass region suggests shape coexistence and competition between pairing correlations in different channels. Recent results concerning the interplay between isospin-mixing and shape-coexistence effects on exotic phenomena in A∼70 nuclei obtained within the beyond-mean-field complex Excited Vampir variational model with symmetry projection before variation using a realistic effective interaction in a relatively large model space are presented. Excited Vampir predictions concerning the Gamow-Teller β decay to the odd-odd N=Z {sup 66}As and {sup 70}Br nuclei correlated with the pair structure analysis in the T=1 and T=0 channel of the involved wave functions are discussed.

  9. Comparison of β-decay and Charge-exchange Reactions in Mirror T=2 Nuclei and Isospin Mixing

    Institute of Scientific and Technical Information of China (English)

    B Rubio; A Poves; S E A Orrigo; A Algora; B Blank; Y Fujita; H Fujita; E Ganioglu; W Gelletly; A Montaner-Piza

    2016-01-01

    We have carried outβdecay studies of proton rich nuclei in the fp shell at different laboratories. Here we present our recent results on the β decay of Tz=−2 nuclei performed at GANIL and compare them with the Charge Exchange reactions on their stable, mirror-partner targets, performed at RCNP. In one of the cases, the 56Zn- 56Fe pair, a strong isospin mixing has been observed. The results are well reproduced in the framework of Shell Model calculations.

  10. Production Uncertainties of p-Nuclei in the γ-Process in Massive Stars Using a Monte Carlo Approach

    Science.gov (United States)

    Rauscher, T.; Nishimura, N.; Hirschi, R.; Cescutti, G.; Murphy, A. St. J.; Heger, A.

    Proton-rich nuclei, the so-called p-nuclei, are made in photodisintegration processes in outer shells of massive stars in the course of the final supernova explosion. Nuclear uncertainties in the production of these nuclei have been quantified in a Monte Carlo procedure. Bespoke temperature-dependent uncertainties were assigned to different types of reactions involving nuclei from Fe to Bi and all rates were varied randomly within the uncertainties. The resulting total production uncertainties of the p-nuclei are below a factor of two, with few exceptions. Key reactions dominating the final uncertainties have been identified in an automated procedure using correlations between rate and abundance uncertainties. Our results are compared to those of a previous study manually varying reaction rates.

  11. Production Uncertainties of p-Nuclei in the $\\gamma$-Process in Massive Stars Using a Monte Carlo Approach

    CERN Document Server

    Rauscher, T; Hirschi, R; Cescutti, G; Murphy, A St J; Heger, A

    2016-01-01

    Proton-rich nuclei, the so-called p-nuclei, are made in photodisintegration processes in outer shells of massive stars in the course of the final supernova explosion. Nuclear uncertainties in the production of these nuclei have been quantified in a Monte Carlo procedure. Bespoke temperature-dependent uncertainties were assigned to different types of reactions involving nuclei from Fe to Bi and all rates were varied randomly within the uncertainties. The resulting total production uncertainties of the p-nuclei are below a factor of two, with few exceptions. Key reactions dominating the final uncertainties have been identified in an automated procedure using correlations between rate and abundance uncertainties. Our results are compared to those of a previous study manually varying reaction rates.

  12. Shell model based reaction rates for rp-process nuclei in the mass range A=44-63

    CERN Document Server

    Fisker, J L; Görres, J; Langanke, K; Martínez-Pinedo, G; Wiescher, M C

    2001-01-01

    We have used large-scale shell-model diagonalization calculations to determine the level spectra, proton spectroscopic factors, and electromagnetic transition probabilities for proton rich nuclei in the mass range A=44-63. Based on these results and the available experimental data, we calculated the resonances for proton capture reactions on neutron deficient nuclei in this mass range. We also calculated the direct capture processes on these nuclei in the framework of a Woods-Saxon potential model. Taking into account both resonant and direct contributions, we determined the ground-state proton capture reaction rates for these nuclei under hot hydrogen burning conditions for temperatures between 10 sup 8 and 10 sup 1 sup 0 K. The calculated compound-nucleus level properties and the reaction rates are presented here; the rates are also available in computer-readable format from the authors.

  13. Elastic scattering, fusion, and breakup of light exotic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Kolata, J.J. [University of Notre Dame, Physics Department, Notre Dame, IN (United States); Guimaraes, V. [Universidade de Sao Paulo, Instituto de Fisica, Sao Paulo, SP (Brazil); Aguilera, E.F. [Instituto Nacional de Investigaciones Nucleares, Departamento de Aceleradores, Mexico, Distrito Federal (Mexico)

    2016-05-15

    The present status of fusion reactions involving light (A< 20) radioactive projectiles at energies around the Coulomb barrier (E<10 MeV per nucleon) is reviewed, emphasizing measurements made within the last decade. Data on elastic scattering (providing total reaction cross section information) and breakup channels for the involved systems, demonstrating the relationship between these and the fusion channel, are also reviewed. Similarities and differences in the behavior of fusion and total reaction cross section data concerning halo nuclei, weakly-bound but less exotic projectiles, and strongly-bound systems are discussed. One difference in the behavior of fusion excitation functions near the Coulomb barrier seems to emerge between neutron-halo and proton-halo systems. The role of charge has been investigated by comparing the fusion excitation functions, properly scaled, for different neutron- and proton-rich systems. Possible physical explanations for the observed differences are also reviewed. (orig.)

  14. The Array for Nuclear Astrophysics Studies with Exotic Nuclei (anasen)

    Science.gov (United States)

    Matos, M.; Blackmon, J. C.; Gardiner, H. E.; Linhardt, L. E.; Macon, K. T.; Mondello, L. L.; Baby, L.; Johnson, E.; Koshchiy, E.; Rogachev, G.; Wiedenhöver, I.; Bardayan, D. W.

    2013-03-01

    Experimental information about most reactions involving short-lived nuclei is limited. New facilities aim to provide wider access to unstable isotopes, but the limited intensities require more efficient and selective techniques and devices. The Array for Nuclear Astrophysics Studies with Exotic Nuclei (ANASEN) is a charged-particle detector array designed primarily for studies of reactions important in the αp- and rp- processes with proton-rich exotic nuclei. The array consists of 40 silicon-strip detectors backed with CsI scintillators. The detectors cover an area of about 1300 cm2 providing essentially complete solid angle coverage for the reactions of interest with good energy and position resolution. ANASEN also includes a position-sensitive annular gas proportional counter that allows it to be used as an active gas target/detector. ANASEN is designed for direct measurement of (α,p) re-actions in inverse kinematics as well as for studies of proton elastic and inelastic scattering, (p, γ) reactions and transfer reactions. The array is being developed by Louisiana State University and Florida State University. Presently it is located at the RESOLUT radioacitve ion beam facility at FSU, where the first experiments are being performed. In the future, the array will be used at the ReA3 facility at the National Superconducting Cyclotron Laboratory.

  15. Studies on Proton-Halo Structure of Light Proton-Rich Nuclei by Elastic Electron-Nucleus Scattering%用电子散射研究丰质子核的质子晕结构

    Institute of Scientific and Technical Information of China (English)

    王再军; 任中洲

    2005-01-01

    理论和实验结果都表明17F的第一激发态有质子晕存在.用相对论平均场理论和Eikonal近似研究了质子晕核17F的第一激发态的电子弹性散射过程.计算了17F的第一激发态的电荷形状因子,并与16O和19F的结果进行了对比和讨论.结果显示质子晕的存在会使中等转移动量的电荷形状因子产生明显的变化,并且使低转移动量的电荷形状因子趋于降低.这说明电子散射对质子晕的存在是非常敏感的,表明可以用电子散射对奇特核的质子晕结构进行更精细的研究.

  16. Constraining the astrophysical origin of the p-nuclei through nuclear physics and meteoritic data

    CERN Document Server

    Rauscher, T; Dillmann, I; Fröhlich, C; Fülöp, Zs; Gyürky, Gy

    2013-01-01

    A small number of naturally occurring, proton-rich nuclides (the p-nuclei) cannot be made in the s- and r-process. Their origin is not well understood. Massive stars can produce p-nuclei through photodisintegration of pre-existing intermediate and heavy nuclei. This so-called gamma-process requires high stellar plasma temperatures and occurs mainly in explosive O/Ne burning during a core-collapse supernova. Although the gamma-process in massive stars has been successful in producing a large range of p-nuclei, significant deficiences remain. An increasing number of processes and sites has been studied in recent years in search of viable alternatives replacing or supplementing the massive star models. A large number of unstable nuclei, however, with only theoretically predicted reaction rates are included in the reaction network and thus the nuclear input may also bear considerable uncertainties. The current status of astrophysical models, nuclear input, and observational constraints is reviewed. After an overv...

  17. Charge-changing transitions and capture strengths of pf-shell nuclei with $T_{z} = -2$ at proton drip-line

    CERN Document Server

    Rahman, Muneeb-Ur

    2016-01-01

    Charge-changing transitions, commonly referred to as Gamow-Teller (GT) transitions, and electron capture/$\\beta^{+}$-decay strengths for pf-shell nuclei with $T_{z} = - 2$ at proton drip-line have been calculated using the proton-neutron quasi-particle random phase approximation (pn-QRPA) model. The total GT$_{+}$ strength values and electron capture/$\\beta^{+}$-decay rates are needed for the study of the late stages of the stellar evolution. The pn-QRPA theory is used for a microscopic calculation of GT strength distribution functions and associated stellar electron capture/$\\beta^{+}$-decay rates of proton-rich pf-shell nuclei with $T_{z} = - 2$ in the mass range 46 $\\leq$ A $\\leq$ 56 at proton drip-line. Standard quenching factor of 0.74, usually implemented in the shell model calculation, has been incorporated for the comparison with experimental data (wherever available). The calculated GT strength of the two proton-rich nuclei, $^{52}$Ni and $^{56}$Zn are compared with experimental data of corresponding...

  18. Electron cooling

    Science.gov (United States)

    Meshkov, I.; Sidorin, A.

    2004-10-01

    The brief review of the most significant and interesting achievements in electron cooling method, which took place during last two years, is presented. The description of the electron cooling facilities-storage rings and traps being in operation or under development-is given. The applications of the electron cooling method are considered. The following modern fields of the method development are discussed: crystalline beam formation, expansion into middle and high energy electron cooling (the Fermilab Recycler Electron Cooler, the BNL cooler-recuperator, cooling with circulating electron beam, the GSI project), electron cooling in traps, antihydrogen generation, electron cooling of positrons (the LEPTA project).

  19. Stochastic Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Blaskiewicz, M.

    2011-01-01

    Stochastic Cooling was invented by Simon van der Meer and was demonstrated at the CERN ISR and ICE (Initial Cooling Experiment). Operational systems were developed at Fermilab and CERN. A complete theory of cooling of unbunched beams was developed, and was applied at CERN and Fermilab. Several new and existing rings employ coasting beam cooling. Bunched beam cooling was demonstrated in ICE and has been observed in several rings designed for coasting beam cooling. High energy bunched beams have proven more difficult. Signal suppression was achieved in the Tevatron, though operational cooling was not pursued at Fermilab. Longitudinal cooling was achieved in the RHIC collider. More recently a vertical cooling system in RHIC cooled both transverse dimensions via betatron coupling.

  20. Spectroscopical study of the yrast and yrare structure in far-from-stability nuclei; Etude spectroscopique de la structure yrast et yrare de noyaux loin de la stabilite

    Energy Technology Data Exchange (ETDEWEB)

    Hoellinger Fabien [Institut de Recherches Subatomiques, 23, Rue du Loess, BP 28, 67037 Strasbourg Cedex 2 (France)]|[Universite Louis Pasteur, 67 - Strasbourg (France)

    1999-01-13

    The nuclear structure study of neutron-rich nuclei was realized with the EUROGAM II array in two different experiments. The first study consisted in the analysis of the product of spontaneous fission of {sup 248}Cm. Three neutron-rich cerium isotopes {sup 147,149,151}Ce were analyzed. A level scheme for {sup 151}Ce is presented for the first time. The yrast structure of the three nuclei does not show alternative parity bands as expected in this region of octupole deformations. We studied the rotational structure of the bands and this leads to suggest Nilsson configurations to some of them. The aim of this second experiment was the study of the nuclei {sup 99}Mo, {sup 101}Tc, {sup 103}Ru. The three nuclei are situated on the neutron-rich side of the nuclear chart and are produced as fission fragments of a heavy-ion induced reaction. Some bands are extended to higher spins and some new bands are observed. The structure of the rotational bands is interpreted by means of the Hartree-Fock-Bogolyubov model. A last experiment intended to study the structure of the proton-rich nucleus {sup 223}Pa has been achieved with the JURO+RITU array located at Jyvaeskylae (Finland). In this proton-rich actinide region, the nuclei develop octupole features around Z{approx_equal}88, N{approx_equal}132. The analysis of this experiment leads to the first assignment of gamma transitions to the {sup 223}Pa. (author) 91 refs., 78 figs., 16 tabs.

  1. A microscopic investigation of the transition form factor in the region of collective multipole excitations of stable and unstable nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Papakonstantinou, P. [Technische Univ. Darmstadt (Germany). Inst. fuer Kernphysik]|[Athens Univ. (Greece). Physics Dept., Nuclear and Particle Physics Section; Mavrommatis, E. [Athens Univ. (Greece). Physics Dept., Nuclear and Particle Physics Section; Wambach, J.; Ponomarev, V.Y. [Technische Univ. Darmstadt (Germany). Inst. fuer Kernphysik

    2004-12-20

    We have used a self-consistent Skyrme-Hartree-Fock plus continuum-RPA model to study the low-multipole response of stable and neutron/proton-rich Ni and Sn isotopes. We focus on the momentum-transfer dependence of the strength distribution, as it provides information on the structure of excited nuclear states and in particular on the variations of the transition form factor (TFF) with the energy. Our results show, among other things, that the TFF may show significant energy dependence in the region of the isoscalar giant monopole resonance and that the TFF corresponding to the threshold strength in the case of neutron-rich nuclei is different compared to the one corresponding to the respective giant resonance. Perspectives are given for more detailed future investigations. (orig.)

  2. Beta decay of the exotic $T_z$ = -2 nuclei $^{48}$Fe, $^{52}$Ni and $^{56}$Zn

    CERN Document Server

    Orrigo, S E A; Fujita, Y; Gelletly, W; Agramunt, J; Algora, A; Ascher, P; Bilgier, B; Blank, B; Cáceres, L; Cakirli, R B; Ganioğlu, E; Gerbaux, M; Giovinazzo, J; Grévy, S; Kamalou, O; Kozer, H C; Kucuk, L; Kurtukian-Nieto, T; Molina, F; Popescu, L; Rogers, A M; Susoy, G; Stodel, C; Suzuki, T; Tamii, A; Thomas, J C

    2016-01-01

    The results of a study of the beta decays of three proton-rich nuclei having $T_z$ = -2, namely $^{48}$Fe, $^{52}$Ni and $^{56}$Zn, produced in an experiment carried out at GANIL, are reported. In all the cases we have extracted the half-lives and the total $\\beta$-delayed proton emission branching ratios. We have measured the individual $\\beta$-delayed protons and $\\beta$-delayed $\\gamma$ rays with their branching ratios. Decay schemes have been determined for the three nuclei, and new energy levels are identified in the corresponding daughter nuclei. Competition between $\\beta$-delayed protons and gammas is observed in the de-excitation of the $T$ = 2 Isobaric Analogue States in all three cases. Absolute Fermi and Gamow-Teller transition strengths have been determined. The mass excesses of the nuclei under study have been deduced. In addition, we discuss in detail the data analysis taking as a test case $^{56}$Zn, where the exotic $\\beta$-delayed $\\gamma$-proton decay has been observed.

  3. Turbulence and cooling in cluster cores

    CERN Document Server

    Banerjee, Nilanjan

    2014-01-01

    We study the interplay between turbulent heating, mixing, and radiative cooling in an idealized model of cool cluster cores. Active galactic nuclei (AGN) jets are expected to drive turbulence and heat cluster cores. Cooling of the intracluster medium (ICM) and stirring by AGN jets are tightly coupled in a feedback loop. We impose the feedback loop by balancing radiative cooling with turbulent heating. In addition to heating the plasma, turbulence also mixes it, suppressing the formation of cold gas at small scales. In this regard, the effect of turbulence is analogous to thermal conduction. For uniform plasma in thermal balance (turbulent heating balancing radiative cooling), cold gas condenses only if the cooling time is shorter than the mixing time. This condition requires the turbulent kinetic energy to be $\\gtrsim$ the plasma internal energy; such high velocities in cool cores are ruled out by observations. The results with realistic magnetic fields and thermal conduction are qualitatively similar to the ...

  4. Quarks in finite nuclei

    CERN Document Server

    Guichon, P A M; Thomas, A W

    1996-01-01

    We describe the development of a theoretical description of the structure of finite nuclei based on a relativistic quark model of the structure of the bound nucleons which interact through the (self-consistent) exchange of scalar and vector mesons.

  5. Danish Cool

    DEFF Research Database (Denmark)

    Toft, Anne Elisabeth

    2016-01-01

    Danish Cool. Keld Helmer-Petersen, Photography and the Photobook Handout exhibition text in English and Chinese by Anne Elisabeth Toft, Curator The exhibition Danish Cool. Keld Helmer-Petersen, Photography and the Photobook presents the ground-breaking work of late Danish photographer Keld Helmer...

  6. Collectivity in A ~ 60 nuclei: Superdeformed and smoothly terminating rotational bands

    Science.gov (United States)

    Svensson, Carl Edward

    The proton-rich nuclei in the A ~ 60 mass region provide an excellent laboratory for studying the interplay between single-particle and collective nuclear excitations. In order to increase the sensitivity of spectroscopic studies of these nuclei, a new method of channel selection based on the measurement of the total energy of all γ rays and charged particles emitted in fusion-evaporation reactions has been developed. This method has been used to identify and study deformed and superdeformed (SD) rotational bands in 62Zn and the N = Z nucleus 60Zn. Two sets of strongly coupled rotational bands have been identified in 62Zn and have been observed up to the terminating states of their respective configurations. Lifetime measurements indicate that the transition quadrupole moments in these bands decrease as termination is approached. These results represent the first observation of the terminating states of rotational bands in the A ~ 60 mass region and confirm the predicted loss of collectivity associated with the phenomenon of smooth band termination. The first superdeformed rotational band in the A ~ 60 mass region has also been identified in 62Zn, establishing a new region of superdeformation for nuclei with neutron and proton numbers N, Z ~ 30. The doubly-magic superdeformed band in the N = Z nucleus 60Zn has been identified. This band corresponds to filling the single-particle orbitals up to the large SD shell gaps at N, Z = 30 and is the natural reference core for the study of A ~ 60 superdeformation. In addition, the observation of linking transitions connecting this band to normal deformed (ND) states provides the first spin, parity, and excitation energy measurements for A ~ 60 SD states. The stretched- E2 character and relatively large B(E2) values of these linking transitions indicate that the decay-out mechanism in 60Zn differs significantly from that observed in heavier nuclei.

  7. Scattering Of Light Nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Quaglioni, S; Navratil, P; Roth, R

    2009-12-15

    The exact treatment of nuclei starting from the constituent nucleons and the fundamental interactions among them has been a long-standing goal in nuclear physics. Above all nuclear scattering and reactions, which require the solution of the many-body quantum-mechanical problem in the continuum, represent an extraordinary theoretical as well as computational challenge for ab initio approaches.We present a new ab initio many-body approach which derives from the combination of the ab initio no-core shell model with the resonating-group method [4]. By complementing a microscopic cluster technique with the use of realistic interactions, and a microscopic and consistent description of the nucleon clusters, this approach is capable of describing simultaneously both bound and scattering states in light nuclei. We will discuss applications to neutron and proton scattering on sand light p-shell nuclei using realistic nucleon-nucleon potentials, and outline the progress toward the treatment of more complex reactions.

  8. A relativistic mean-field study of magic numbers in light nuclei from neutron to proton drip-lines

    Indian Academy of Sciences (India)

    T K Jha; M S Mehta; S K Patra; B K Raj; Raj K Gupta

    2003-09-01

    In an axially deformed relativistic mean-field calculation of single-particle energy spectra of = 8 (Li–Mg) and = 14, 16 (C–Mg) isotonic chain and the one- and two-neutron separation energies of various isotopes of Li–Mg, new magic numbers are found to exist at = 6 and = 16 and/or = 14, which are in addition to the = 8 and = 20 magic numbers. In neutron-rich nuclei, the shell gap at = 6 is larger than at = 8 and a large gap is observed for = 16 or 14 for the neutron-rich and = 14 for proton-rich nuclei. Large shell gaps are also found to exist at = 14 and 16 or = 16 alone for nuclei near the -stability line. The above results are independent of the parameter sets TM2, NL3 and NL–SH used here. Similarly, new large shell gaps are predicted at = 6, 16 and/or 14 for protons.

  9. Anharmonic vibrations in nuclei

    CERN Document Server

    Fallot, M; Andrés, M V; Catara, F; Lanza, E G; Scarpaci, J A; Chomaz, Ph.

    2003-01-01

    In this letter, we show that the non-linearitites of large amplitude motions in atomic nuclei induce giant quadrupole and monopole vibrations. As a consequence, the main source of anharmonicity is the coupling with configurations including one of these two giant resonances on top of any state. Two-phonon energies are often lowered by one or two MeV because of the large matrix elements with such three phonon configurations. These effects are studied in two nuclei, 40Ca and 208Pb.

  10. The shapes of nuclei

    CERN Document Server

    Bertsch, G F

    2016-01-01

    Gerry Brown initiated some early studies on the coexistence of different nuclear shapes. The subject has continued to be of interest and is crucial for understanding nuclear fission. We now have a very good picture of the potential energy surface with respect to shape degrees of freedom in heavy nuclei, but the dynamics remain problematic. In contrast, the early studies on light nuclei were quite successful in describing the mixing between shapes. Perhaps a new approach in the spirit of the old calculations could better elucidate the character of the fission dynamics and explain phenomena that current theory does not model well.

  11. Elusive active galactic nuclei

    NARCIS (Netherlands)

    Maiolino, R; Comastri, A; Gilli, R; Nagar, NM; Bianchi, S; Boker, T; Colbert, E; Krabbe, A; Marconi, A; Matt, G; Salvati, M

    2003-01-01

    A fraction of active galactic nuclei do not show the classical Seyfert-type signatures in their optical spectra, i.e. they are optically 'elusive'. X-ray observations are an optimal tool to identify this class of objects. We combine new Chandra observations with archival X-ray data in order to obtai

  12. Molecular outflows in starburst nuclei

    CERN Document Server

    Roy, Arpita; Sharma, Prateek; Shchekinov, Yuri

    2016-01-01

    Recent observations have detected molecular outflows in a few nearby starburst nuclei. We discuss the physical processes at work in such an environment in order to outline a scenario that can explain the observed parameters of the phenomenon, such as the molecular mass, speed and size of the outflows. We show that outflows triggered by OB associations, with $N_{OB}\\ge 10^5$ (corresponding to a star formation rate (SFR)$\\ge 1$ M$_{\\odot}$ yr$^{-1}$ in the nuclear region), in a stratified disk with mid-plane density $n_0\\sim 200\\hbox{--}1000$ cm$^{-3}$ and scale height $z_0\\ge 200 (n_0/10^2 \\, {\\rm cm}^{-3})^{-3/5}$ pc, can form molecules in a cool dense and expanding shell. The associated molecular mass is $\\ge 10^7$ M$_\\odot$ at a distance of a few hundred pc, with a speed of several tens of km s$^{-1}$. We show that a SFR surface density of $10 \\le \\Sigma_{SFR} \\le 50$ M$_\\odot$ yr$^{-1}$ kpc$^{-2}$ favours the production of molecular outflows, consistent with observed values.

  13. Shape Deformations in Atomic Nuclei

    CERN Document Server

    Hamamoto, Ikuko

    2011-01-01

    The ground states of some nuclei are described by densities and mean fields that are spherical, while others are deformed. The existence of non-spherical shape in nuclei represents a spontaneous symmetry breaking.

  14. Ventilative Cooling

    DEFF Research Database (Denmark)

    Heiselberg, Per Kvols; Kolokotroni, Maria

    This report, by venticool, summarises the outcome of the work of the initial working phase of IEA ECB Annex 62 Ventilative Cooling and is based on the findings in the participating countries. It presents a summary of the first official Annex 62 report that describes the state-of-the-art of ventil......This report, by venticool, summarises the outcome of the work of the initial working phase of IEA ECB Annex 62 Ventilative Cooling and is based on the findings in the participating countries. It presents a summary of the first official Annex 62 report that describes the state...

  15. Ultra High Energy Nuclei Propagation

    CERN Document Server

    Aloisio, Roberto

    2008-01-01

    We discuss the problem of ultra high energy nuclei propagation in astrophysical backgrounds. We present a new analytical computation scheme based on the hypothesis of continuos energy losses in a kinetic formulation of the particles propagation. This scheme enables the computation of the fluxes of ultra high energy nuclei as well as the fluxes of secondaries (nuclei and nucleons) produced by the process of photo-disintegration suffered by nuclei.

  16. Cool snacks

    DEFF Research Database (Denmark)

    Grunert, Klaus G; Brock, Steen; Brunsø, Karen

    2016-01-01

    such a product requires an interdisciplinary effort where researchers with backgrounds in psychology, anthropology, media science, philosophy, sensory science and food science join forces. We present the COOL SNACKS project, where such a blend of competences was used first to obtain thorough insight into young...

  17. Bubble nuclei; Noyaux Bulles

    Energy Technology Data Exchange (ETDEWEB)

    Legoll, F. [Service de Physique Theorique, CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France)

    1998-07-22

    For nuclei with very high electrical charge, the Coulomb field is expected to drive the protons away from the centre to the surface of the nucleus. Such a nucleus would be no more compact but look like a bubble. The goal of this work is to confirm this idea. We are interested in only the ground state of spherical nuclei. We use the Skyrme potential with the Sly4 parametrization to calculate the mean-field Hamiltonian. Paring correlations are described by a surface-active delta paring interaction. In its ground state the nucleus {sup A=900} X{sub Z=274} is shown to be a bubble. Another stable state is found with a little higher energy: it is also a bubble. (author) 11 refs., 18 figs., 33 tabs.

  18. Bubble nuclei; Noyaux Bulles

    Energy Technology Data Exchange (ETDEWEB)

    Legoll, F. [Service de Physique Theorique, CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France)

    1998-07-22

    For nuclei with very high electrical charge, the Coulomb field is expected to drive the protons away from the centre to the surface of the nucleus. Such a nucleus would be no more compact but look like a bubble. The goal of this work is to confirm this idea. We are interested in only the ground state of spherical nuclei. We use the Skyrme potential with the Sly4 parametrization to calculate the mean-field Hamiltonian. Paring correlations are described by a surface-active delta paring interaction. In its ground state the nucleus {sup A=900} X{sub Z=274} is shown to be a bubble. Another stable state is found with a little higher energy: it is also a bubble. (author) 11 refs., 18 figs., 33 tabs.

  19. Stochastic cooling

    Energy Technology Data Exchange (ETDEWEB)

    Bisognano, J.; Leemann, C.

    1982-03-01

    Stochastic cooling is the damping of betatron oscillations and momentum spread of a particle beam by a feedback system. In its simplest form, a pickup electrode detects the transverse positions or momenta of particles in a storage ring, and the signal produced is amplified and applied downstream to a kicker. The time delay of the cable and electronics is designed to match the transit time of particles along the arc of the storage ring between the pickup and kicker so that an individual particle receives the amplified version of the signal it produced at the pick-up. If there were only a single particle in the ring, it is obvious that betatron oscillations and momentum offset could be damped. However, in addition to its own signal, a particle receives signals from other beam particles. In the limit of an infinite number of particles, no damping could be achieved; we have Liouville's theorem with constant density of the phase space fluid. For a finite, albeit large number of particles, there remains a residue of the single particle damping which is of practical use in accumulating low phase space density beams of particles such as antiprotons. It was the realization of this fact that led to the invention of stochastic cooling by S. van der Meer in 1968. Since its conception, stochastic cooling has been the subject of much theoretical and experimental work. The earliest experiments were performed at the ISR in 1974, with the subsequent ICE studies firmly establishing the stochastic cooling technique. This work directly led to the design and construction of the Antiproton Accumulator at CERN and the beginnings of p anti p colliding beam physics at the SPS. Experiments in stochastic cooling have been performed at Fermilab in collaboration with LBL, and a design is currently under development for a anti p accumulator for the Tevatron.

  20. Symmetries in Nuclei

    CERN Document Server

    Van Isacker, P

    2010-01-01

    The use of dynamical symmetries or spectrum generating algebras for the solution of the nuclear many-body problem is reviewed. General notions of symmetry and dynamical symmetry in quantum mechanics are introduced and illustrated with simple examples such as the SO(4) symmetry of the hydrogen atom and the isospin symmetry in nuclei. Two nuclear models, the shell model and the interacting boson model, are reviewed with particular emphasis on their use of group-theoretical techniques.

  1. On Quasibound N* Nuclei

    CERN Document Server

    Kelkar, N G; Moskal, P

    2015-01-01

    The possibility for the existence of unstable bound states of the S11 nucleon resonance N$^*$(1535) and nuclei is investigated. These quasibound states are speculated to be closely related to the existence of the quasibound states of the eta mesons and nuclei. Within a simple model for the N N$^*$ interaction involving a pion and eta meson exchange, N$^*$-nucleus potentials for N*-$^3$He and N*-$^{24}$Mg are evaluated and found to be of a Woods-Saxon like form which supports two to three bound states. In case of N*-$^3$He, one state bound by only a few keV and another by 4 MeV is found. The results are however quite sensitive to the N N$^*$ $\\pi$ and N N$^*$ $\\eta$ vertex parameters. A rough estimate of the width of these states, based on the mean free path of the exchanged mesons in the nuclei leads to very broad states with $\\Gamma \\sim$ 80 and 110 MeV for N*-$^3$He and N*-$^{24}$Mg respectively.

  2. Formation of nuclei during precipitation in metallic mixed crystals

    Science.gov (United States)

    Becker, R.

    1988-01-01

    Assuming that the energy of a mixed crystal can be calculated by simple addition of neighboring bonds, the nuclear formation energy is calculated for precipation in a super-saturated binary mixed crystal. From this can be determined the frequency of the formation of nuclei. From the calculation of a numerical example we can obtain, for the degree of sub-cooling at which the frequency of the formation of nuclei reaches its maximum, satisfactory agreement with available measurements of the rate of precipitation.

  3. A very cool cooling system

    CERN Multimedia

    Antonella Del Rosso

    2015-01-01

    The NA62 Gigatracker is a jewel of technology: its sensor, which delivers the time of the crossing particles with a precision of less than 200 picoseconds (better than similar LHC detectors), has a cooling system that might become the precursor to a completely new detector technique.   The 115 metre long vacuum tank of the NA62 experiment. The NA62 Gigatracker (GTK) is composed of a set of three innovative silicon pixel detectors, whose job is to measure the arrival time and the position of the incoming beam particles. Installed in the heart of the NA62 detector, the silicon sensors are cooled down (to about -20 degrees Celsius) by a microfluidic silicon device. “The cooling system is needed to remove the heat produced by the readout chips the silicon sensor is bonded to,” explains Alessandro Mapelli, microsystems engineer working in the Physics department. “For the NA62 Gigatracker we have designed a cooling plate on top of which both the silicon sensor and the...

  4. Cooling technique

    Energy Technology Data Exchange (ETDEWEB)

    Salamon, Todd R; Vyas, Brijesh; Kota, Krishna; Simon, Elina

    2017-01-31

    An apparatus and a method are provided. Use is made of a wick structure configured to receive a liquid and generate vapor in when such wick structure is heated by heat transferred from heat sources to be cooled off. A vapor channel is provided configured to receive the vapor generated and direct said vapor away from the wick structure. In some embodiments, heat conductors are used to transfer the heat from the heat sources to the liquid in the wick structure.

  5. Skyrmions and Nuclei

    Science.gov (United States)

    Battye, R. A.; Manton, N. S.; Sutcliffe, P. M.

    We review recent work on the modelling of atomic nuclei as quantised Skyrmions, using Skyrme's original model with pion fields only. Skyrmions are topological soliton solutions, whose conserved topological charge B is identified with the baryon number of a nucleus. Apart from an energy and length scale, the Skyrme model has just one dimensionless parameter m, proportional to the pion mass. It has been found that a good fit to experimental nuclear data requires m to be of order 1. The Skyrmions for B up to 7 have been known for some time, and are qualitatively insensitive to whether m is zero or of order 1. However, for baryon numbers B = 8 and above, the Skyrmions have quite a compact structure for m of order 1, rather than the hollow polyhedral structure found when m = 0. One finds for baryon numbers which are multiples of four, that the Skyrmions are composed of B = 4 sub-units, as in the α-particle model of nuclei. The rational map ansatz gives a useful approximation to the Skyrmion solutions for all baryon numbers when m = 0. For m of order 1, it gives a good approximation for baryon numbers up to 7, and generalisations of this ansatz are helpful for higher baryon numbers. We briefly review the work from the 1980s and 90s on the semiclassical rigidbody quantisation of Skyrmions for B = 1, 2, 3 and 4. We then discuss more recent work extending this method to B = 6, 7, 8, 10 and 12. We determine the quantum states of the Skyrmions, finding their spins, isospins and parities, and compare with the experimental data on the ground and excited states of nuclei up to mass number 12.

  6. Active galactic nuclei

    CERN Document Server

    Beckmann, Volker

    2012-01-01

    This AGN textbook includes phenomena based on new results in the X-Ray domain from new telescopes such as Chandra and XMM Newton not mentioned in any other book. Furthermore, it considers also the Fermi Gamma Ray Space Telescope with its revolutionary advances of unprecedented sensitivity, field of view and all-sky monitoring. Those and other new developments as well as simulations of AGN merging events and formations, enabled through latest super-computing capabilities. The book gives an overview on the current knowledge of the Active Galacitc Nuclei phenomenon. The spectral energy d

  7. Active galactic nuclei

    CERN Document Server

    Blandford, RD; Woltjer, L

    1990-01-01

    Starting with this volume, the Lecture Notes of the renowned Advanced Courses of the Swiss Society for Astrophysics and Astronomy will be published annually. In each course, three extensive lectures given by leading experts in their respective fields cover different and essential aspects of the subject. The 20th course, held at Les Diablerets in April 1990, dealt with current research on active galactic nuclei; it represents the most up-to-date views on the subject, presented with particular regard for clarity. The previous courses considered a wide variety of subjects, beginning with ""Theory

  8. Visibility of comet nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Ney, E.P.

    1982-01-22

    Photography of the nucleus of comet Halley is the goal of several planned space missions. The nucleus of a comet is surrounded by a cloud of dust particles. If this cloud is optically thick, it will prevent observation of the nuclear surface. Broadband photometry of nine comets has been analyzed to determine the visibility of their nuclei. Only in the case of comet West near perihelion was the dust dense enough to interfere with imaging. Comparison of the visual brightness of the well-observed comets with that of Halley in 1910 leads to the conclusion that the nucleus of Halley can be imaged without significant obscuration by the dust.

  9. Elusive Active Galactic Nuclei

    CERN Document Server

    Maiolino, R; Gilli, R; Nagar, N M; Bianchi, S; Böker, T; Colbert, E; Krabbe, A; Marconi, A; Matt, G; Salvati, M

    2003-01-01

    A fraction of active galactic nuclei do not show the classical Seyfert-type signatures in their optical spectra, i.e. they are optically "elusive". X-ray observations are an optimal tool to identify this class of objects. We combine new Chandra observations with archival X-ray data in order to obtain a first estimate of the fraction of elusive AGN in local galaxies and to constrain their nature. Our results suggest that elusive AGN have a local density comparable to or even higher than optically classified Seyfert nuclei. Most elusive AGN are heavily absorbed in the X-rays, with gas column densities exceeding 10^24 cm^-2, suggesting that their peculiar nature is associated with obscuration. It is likely that in elusive AGN, the nuclear UV source is completely embedded and the ionizing photons cannot escape, which prevents the formation of a classical Narrow Line Region. Elusive AGN may contribute significantly to the 30 keV bump of the X-ray background.

  10. NEW EQUATIONS OF STATE BASED ON THE LIQUID DROP MODEL OF HEAVY NUCLEI AND QUANTUM APPROACH TO LIGHT NUCLEI FOR CORE-COLLAPSE SUPERNOVA SIMULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Furusawa, Shun; Yamada, Shoichi [Advanced Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Sumiyoshi, Kohsuke [Numazu College of Technology, Ooka 3600, Numazu, Shizuoka 410-8501 (Japan); Suzuki, Hideyuki, E-mail: furusawa@heap.phys.waseda.ac.jp [Faculty of Science and Technology, Tokyo University of Science, Yamazaki 2641, Noda, Chiba 278-8510 (Japan)

    2013-08-01

    We construct new equations of state for baryons at subnuclear densities for the use in core-collapse simulations of massive stars. The abundance of various nuclei is obtained together with thermodynamic quantities. A model free energy is constructed, based on the relativistic mean field theory for nucleons and the mass formula for nuclei with the proton number up to {approx}1000. The formulation is an extension of the previous model, in which we adopted the liquid drop model to all nuclei under the nuclear statistical equilibrium. We reformulate the new liquid drop model so that the temperature dependences of bulk energies could be taken into account. Furthermore, we extend the region in the nuclear chart, in which shell effects are included, by using theoretical mass data in addition to experimental ones. We also adopt a quantum-theoretical mass evaluation of light nuclei, which incorporates the Pauli- and self-energy shifts that are not included in the ordinary liquid drop model. The pasta phases for heavy nuclei are taken into account in the same way as in the previous model. We find that the abundances of heavy nuclei are modified by the shell effects of nuclei and temperature dependence of bulk energies. These changes may have an important effect on the rates of electron captures and coherent neutrino scatterings on nuclei in supernova cores. The abundances of light nuclei are also modified by the new mass evaluation, which may affect the heating and cooling rates of supernova cores and shocked envelopes.

  11. Electron scattering for exotic nuclei

    Indian Academy of Sciences (India)

    Toshimi Suda

    2014-11-01

    A brand-new electron scattering facility, the SCRIT Electron Scattering Facility, will soon start its operation at RIKEN RI Beam Factory, Japan. This is the world’s first electron scattering facility dedicated to the structure studies of short-lived nuclei. The goal of this facility is to determine the charge density distributions of short-lived exotic nuclei by elastic electron scattering. The first collision between electrons and exotic nuclei will be observed in the year 2014.

  12. Laser-coolable polyatomic molecules with heavy nuclei

    CERN Document Server

    Isaev, T A; Eliav, E

    2016-01-01

    Recently a number of diatomic and polyatomics molecules has been identified as a prospective systems for Doppler cooling. Polyatomic molecules with heavy nuclei present great interest for search for new physics outside of Standard Model and a large variety of other applications including cold chemistry, quantum informatics etc. Herein we propose radium monohydroxide molecule (RaOH) which is on the one hand amenable for Doppler cooling and on the other hand has considerable potential for searching for $\\cal P$-odd and $\\cal P,T$-odd effects.

  13. ATLAS - Liquid Cooling Systems

    CERN Multimedia

    Bonneau, P.

    1998-01-01

    Photo 1 - Cooling Unit - Side View Photo 2 - Cooling Unit - Detail Manifolds Photo 3 - Cooling Unit - Rear View Photo 4 - Cooling Unit - Detail Pump, Heater and Exchanger Photo 5 - Cooling Unit - Detail Pump and Fridge Photo 6 - Cooling Unit - Front View

  14. Simulation of molecular dynamics of silver subcritical nuclei and crystal clusters during solidification

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Molecular dynamics simulation is carried out to investigate the effects of cooling rate on the final configurations of silver after rapid solidification. The cooling rate for the formation of a silver amorphous phase is determined by analyzing its pair distribution function, H-A bond index, and the largest crystal cluster. Further, the equilibrium structures of the subcritical nuclei and crystal clusters are studied. The results show that the solidified microstructure is composed of a mixture of crystal clusters and amorphous phases at a certain cooling rate range. The size of the largest crystal cluster decreases with the increasing cooling rate, and it completely disappears when the cooling rate exceeds a critical value. The structures of the subcritical nuclei and the largest crystal cluster are composed of lamellar structures of fcc and hcp atoms, indicating that the lamellar structure of fcc and hcp atoms in the silver crystal originates from nucleation, and not from the growth of crystals.

  15. Clusters in nuclei

    CERN Document Server

    Following the pioneering discovery of alpha clustering and of molecular resonances, the field of nuclear clustering is today one of those domains of heavy-ion nuclear physics that faces the greatest challenges, yet also contains the greatest opportunities. After many summer schools and workshops, in particular over the last decade, the community of nuclear molecular physicists has decided to collaborate in producing a comprehensive collection of lectures and tutorial reviews covering the field. This third volume follows the successful Lect. Notes Phys. 818 (Vol. 1) and 848 (Vol. 2), and comprises six extensive lectures covering the following topics:  - Gamma Rays and Molecular Structure - Faddeev Equation Approach for Three Cluster Nuclear Reactions - Tomography of the Cluster Structure of Light Nuclei Via Relativistic Dissociation - Clustering Effects Within the Dinuclear Model : From Light to Hyper-heavy Molecules in Dynamical Mean-field Approach - Clusterization in Ternary Fission - Clusters in Light N...

  16. Gluon density in nuclei

    CERN Document Server

    Ayala, A P; Levin, E M

    1996-01-01

    In this talk we present our detail study ( theory and numbers) [1] on the shadowing corrections to the gluon structure functions for nuclei. Starting from rather contraversial information on the nucleon structure function which is originated by the recent HERA data, we develop the Glauber approach for the gluon density in a nucleus based on Mueller formula [2] and estimate the value of the shadowing corrections in this case. Than we calculate the first corrections to the Glauber approach and show that these corrections are big. Based on this practical observation we suggest the new evolution equation which takes into account the shadowing corrections and solve it. We hope to convince you that the new evolution equation gives a good theoretical tool to treat the shadowing corrections for the gluons density in a nucleus and, therefore, it is able to provide the theoretically reliable initial conditions for the time evolution of the nucleus - nucleus cascade.

  17. Pulsars: Gigantic Nuclei

    CERN Document Server

    Xu, Renxin

    2011-01-01

    What is the real nature of pulsars? This is essentially a question of the fundamental strong interaction between quarks at low-energy scale and hence of the non-perturbative quantum chromo-dynamics, the solution of which would certainly be meaningful for us to understand one of the seven millennium prize problems (i.e., "Yang-Mills Theory") named by the Clay Mathematical Institute. After a historical note, it is argued here that a pulsar is very similar to an extremely big nucleus, but is a little bit different from the {\\em gigantic nucleus} speculated 80 years ago by L. Landau. The paper demonstrates the similarity between pulsars and gigantic nuclei from both points of view: the different manifestations of compact stars and the general behavior of the strong interaction.

  18. Nucleomorphs: enslaved algal nuclei.

    Science.gov (United States)

    Cavalier-Smith, T

    2002-12-01

    Nucleomorphs of cryptomonad and chlorarachnean algae are the relict, miniaturised nuclei of formerly independent red and green algae enslaved by separate eukaryote hosts over 500 million years ago. The complete 551 kb genome sequence of a cryptomonad nucleomorph confirms that cryptomonads are eukaryote-eukaryote chimeras and greatly illuminates the symbiogenetic event that created the kingdom Chromista and their alveolate protozoan sisters. Nucleomorph membranes may, like plasma membranes, be more enduring after secondary symbiogenesis than are their genomes. Partial sequences of chlorarachnean nucleomorphs indicate that genomic streamlining is limited by the mutational difficulty of removing useless introns. Nucleomorph miniaturisation emphasises that selection can dramatically reduce eukaryote genome size and eliminate most non-functional nuclear non-coding DNA. Given the differential scaling of nuclear and nucleomorph genomes with cell size, it follows that most non-coding nuclear DNA must have a bulk-sequence-independent function related to cell volume.

  19. Collective excitations in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Chomaz, Ph. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France); Collaboration: La Direction des Sciences de la Matiere du CEA (FR); Le Fonds National de la Recherche Scientifique de Belgique (BE)

    1998-12-31

    The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular, the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of this collective motions is a very good tool to understand the properties of the nucleus itself. The purpose of this article is to stress some aspects of these collective vibrations. We have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. Understanding of these phenomena remains one of the important subjects of actuality in the context of quantal systems in strong interaction. In particular, the study of the states with one or two vibration quanta provides a direct information on the structure of nuclei close to their ground states. Moreover, some collective states appear to be very robust against the onset of chaos. This is the case of the hot giant dipole built on top of a hot nucleus which seems to survive up to rather high temperatures. Their sudden disappearance is still a subject of controversy. It may be that the mean-field and the associated collective states are playing a crucial role also in catastrophic processes such as the phase-transitions. Indeed, when the system is diluted the collective vibrations may become unstable and it seems that these unstable modes provide a natural explanation to the self organization of the system in drops. Finally, considering the diversity of the different structures of exotic nuclei one may expect new vibration types. All these studies are showing the diversity of the collective motions of strongly correlated quantum systems such as the nucleus but many open questions remain to be solved. (authors) 304 refs., 53 figs., 5 tabs.

  20. Cool visitors

    CERN Multimedia

    2006-01-01

    Pictured, from left to right: Tim Izo (saxophone, flute, guitar), Bobby Grant (tour manager), George Pajon (guitar). What do the LHC and a world-famous hip-hop group have in common? They are cool! On Saturday, 1st July, before their appearance at the Montreux Jazz Festival, three members of the 'Black Eyed Peas' came on a surprise visit to CERN, inspired by Dan Brown's Angels and Demons. At short notice, Connie Potter (Head of the ATLAS secretariat) organized a guided tour of ATLAS and the AD 'antimatter factory'. Still curious, lead vocalist Will.I.Am met CERN physicist Rolf Landua after the concert to ask many more questions on particles, CERN, and the origin of the Universe.

  1. Quarks in Few Body Nuclei

    Science.gov (United States)

    Holt, Roy J.

    2016-03-01

    Electron scattering at very high Bjorken x from hadrons provides an excellent test of models, has an important role in high energy physics, and from nuclei, provides a window into short range correlations. Light nuclei have a key role because of the relatively well-known nuclear structure. The development of a novel tritium target for Jefferson Lab has led to renewed interest in the mass three system. For example, deep inelastic scattering experiments in the light nuclei provide a powerful means to determine the neutron structure function. The isospin dependence of electron scattering from mass-3 nuclei provide information on short range correlations in nuclei. The program using the new tritium target will be presented along with a summary of other experiments aimed at revealing the large-x structure of the nucleon.

  2. Quarks in Few Body Nuclei

    Directory of Open Access Journals (Sweden)

    Holt Roy J.

    2016-01-01

    Full Text Available Electron scattering at very high Bjorken x from hadrons provides an excellent test of models, has an important role in high energy physics, and from nuclei, provides a window into short range correlations. Light nuclei have a key role because of the relatively well-known nuclear structure. The development of a novel tritium target for Jefferson Lab has led to renewed interest in the mass three system. For example, deep inelastic scattering experiments in the light nuclei provide a powerful means to determine the neutron structure function. The isospin dependence of electron scattering from mass-3 nuclei provide information on short range correlations in nuclei. The program using the new tritium target will be presented along with a summary of other experiments aimed at revealing the large-x structure of the nucleon.

  3. Cavitation inception from bubble nuclei

    DEFF Research Database (Denmark)

    Mørch, Knud Aage

    2015-01-01

    , and experimental investigations of bubbles and cavitation inception have been presented. These results suggest that cavitation nuclei in equilibrium are gaseous voids in the water, stabilized by a skin which allows diffusion balance between gas inside the void and gas in solution in the surrounding liquid....... The cavitation nuclei may be free gas bubbles in the bulk of water, or interfacial gaseous voids located on the surface of particles in the water, or on bounding walls. The tensile strength of these nuclei depends not only on the water quality but also on the pressure-time history of the water. A recent model......The tensile strength of ordinary water such as tap water or seawater is typically well below 1 bar. It is governed by cavitation nuclei in the water, not by the tensile strength of the water itself, which is extremely high. Different models of the nuclei have been suggested over the years...

  4. The cochlear nuclei of snakes.

    Science.gov (United States)

    Miller, M R

    1980-08-15

    The cochlear nuclei of three burrowing snakes (Xenopeltis unicolor, Cylindrophis rufus, and Eryx johni) and three non-burrowing snakes (Epicrates cenchris, Natrix sipedon, and Pituophis catenifer) were studied. The posterior branch of the statoacoustic nerve and its posterior ganglion were destroyed and the degenerated nerve fibers and terminals traced to primary cochlear nuclei in 13 specimens of Pituophis catenifer. All these snake species possess three primary and one secondary cochlear nuclei. The primary cochlear nuclei consist of a small nucleus angularis located at the cerebello-medullary junction and a fairly large nucleus magnocellularis forming a dorsal cap over the cephalic end of the alar eminence. Nucleus magnocellularis may be subdivided into a medially placed group of rounder cells, nucleus magnocellularis medialis, and a laterally placed group of more ovate and paler-staining cells, nucleus magnocellularis lateralis. A small but well-defined secondary nucleus which showed no degenerated nerve terminals after nerve root section, nucleus laminaris, underlies the cephalic part of both nucleus magnocellularis medialis and nucleus magnocellularis lateralis. Larger and better-developed cochlear nuclei were found in burrowing species than in non-burrowing species of snakes. Of the three burrowing species studied, Xenopeltis showed the greatest development of cochlear nuclei; Eryx cochlear nuclei were not quite as large but were better differentiated than in Xenopeltis; and Cylindrophis cochlear nuclei were fairly large but not as well developed nor as well differentiated as in either Xenopeltis or Eryx. The cochlear nuclei of the three non-burrowing snakes, Epicrates, Natrix, and Pituophis, were not as large nor as well developed as those of the burrowing snakes. There is some, but not complete, correlation between cochlear development and papilla basilaris length and number of hair cells. Thus, Xenopeltis and Eryx, with well-developed cochlear nuclei

  5. Collective excitations in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Chomaz, Ph

    1997-12-31

    The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of these collective motions is a very good to understand the properties of the nucleus itself. The purpose of this article was to stress some aspects of these collective vibrations. In particular we have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. The understanding of these phenomena remains one of the important subjects of actually in the context of quantal systems in strong interaction. In particular the study of the states with one or two vibration quanta provides a direct information on the structure if nuclei close to their ground states. (author) 270 refs.

  6. Gluon density in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Ayala, A.L. [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Inst. de Fisica][Pelotas Univ., RS (Brazil). Inst. de Fisica e Matematica; Ducati, M.B.G. [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Inst. de Fisica; Levin, E.M. [Fermi National Accelerator Lab., Batavia, IL (United States)][Nuclear Physics Inst., St. Petersburg (Russian Federation)

    1996-10-01

    In this talk we present our detailed study (theory and numbers) on the shadowing corrections to the gluon structure functions for nuclei. Starting from rather controversial information on the nucleon structure function which is originated by the recent HERA data, we develop the Glauber approach for the gluon density in a nucleus based on Mueller formula and estimate the value of the shadowing corrections in this case. Then we calculate the first corrections to the Glauber approach and show that these corrections are big. Based on this practical observation we suggest the new evolution equation which takes into account the shadowing corrections and solve it. We hope to convince you that the new evolution equation gives a good theoretical tool to treat the shadowing corrections for the gluons density in a nucleus and, therefore, it is able to provide the theoretically reliable initial conditions for the time evolution of the nucleus-nucleus cascade. The initial conditions should be fixed both theoretically and phenomenologically before to attack such complicated problems as the mixture of hard and soft processes in nucleus-nucleus interactions at high energy or the theoretically reliable approach to hadron or/and parton cascades for high energy nucleus-nucleus interaction. 35 refs., 24 figs., 1 tab.

  7. Monopole transitions in hot nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Sujkowski, Z. [Soltan Inst. for Nuclear Studies, Otwock-Swierk (Poland)

    1994-12-31

    Monopole transitions can be a signature of shape changing in a hot, pulsating nucleus (the low energy E0 mode) and/or a measure of the compressibility of finite nuclei (GMR, the breathing mode). Experimental information pertaining to GMR is reviewed. Recipes for deducing the incompressibility modules for infinite nuclear matter from data on GMR are discussed. Astrophysical implications are outlined. The first attempts at locating the GMR strength in moderately hot nuclei are described. Prospects for improving the experimental techniques to make an observation of this strength in selected nuclei unambiguous are discussed. (author). 46 refs, 8 figs.

  8. Spectroscopy of heavy fissionable nuclei

    Indian Academy of Sciences (India)

    S K Tandel

    2015-09-01

    Structural studies of heavy nuclei are quite challenging due to increased competition from fission, particularly at high spins. Nuclei in the actinide region exhibit a variety of interesting phenomena. Recent advances in instrumentation and analysis techniques have made feasible sensitive measurements of nuclei populated with quite low cross-sections. These include isomers and rotational band structures in isotopes of Pu ( = 94) to Rf ( = 104), and octupole correlations in the Th ( = 90) region. The obtained experimental data have provided insights on various aspects like moments of inertia and nucleon alignments at high spins, quasiparticle energies and evolution of quadrupole and octupole collectivity, among others. An overview of some of these results is presented.

  9. Pseudospin Dynamical Symetry in Nuclei

    CERN Document Server

    Ginocchio, Joseph N

    2014-01-01

    Pseudospin symmetry has been useful in understanding atomic nuclei. We review the arguments that this symmetry is a relativistic symmetry. The condition for this symmetry is that the sum of the vector and scalar potentials in the Dirac Hamiltonian is a constant. We give the generators of pseudospin symmetry. We review some of the predictions that follow from this insight into the relativistic origins of pseudospin symmetry. Since in nuclei the sum of the scalar and vector potentials is not zero but is small, we discuss preliminary investigations into the conditions on the potentials to produce partial dynamic pseudospin symmetry. Finally we show that approximate pseudospin symmetry in nuclei predicts approximate spin symmetry in anti-nucleon scattering from nuclei.

  10. Physics with loosely bound nuclei

    Indian Academy of Sciences (India)

    Chhanda Samanta

    2001-08-01

    The essential aspect of contemporary physics is to understand properties of nucleonic matter that constitutes the world around us. Over the years research in nuclear physics has provided strong guidance in understanding the basic principles of nuclear interactions. But, the scenario of nuclear physics changed drastically as the new generation of accelerators started providing more and more rare isotopes, which are away from the line of stability. These weakly bound nuclei are found to exhibit new forms of nuclear matter and unprecedented exotic behaviour. The low breakup thresholds of these rare nuclei are posing new challenges to both theory and experiments. Fortunately, nature has provided a few loosely bound stable nuclei that have been studied thoroughly for decades. Attempts are being made to find a consistent picture for the unstable nuclei starting from their stable counterparts. Some significant differences in the structure and reaction mechanisms are found.

  11. Black holes, cooling flows and galaxy formation.

    Science.gov (United States)

    Peacock, J A

    2005-03-15

    Central black holes in galaxies are now well established as a ubiquitous phenomenon, and this fact is important for theories of cosmological structure formation. Merging of galaxy haloes must preserve the proportionality between black hole mass and baryonic mass; the way in which this happens may help solve difficulties with existing ing models of galaxy formation, which suffer from excessive cooling and thus over- produce stars. Feedback from active nuclei may be the missing piece of the puzzle, regulating galaxy-scale cooling flows. Such a process now seems to be observed in cluster-scale cooling flows, where dissipation of sound waves generated by radio lobes can plausibly balance the energy lost in X-rays, at least in a time-averaged sense.

  12. Probing the circumgalactic medium of active galactic nuclei with background quasars

    CERN Document Server

    Kacprzak, Glenn G; Murphy, Michael T; Cooke, Jeff

    2014-01-01

    We performed a detailed study of the extended cool gas, traced by MgII absorption [$W_r(2796)\\geq0.3$~{\\AA}], surrounding 14 narrow-line active galactic nuclei (AGNs) at 0.1250$ km/s, indicating outflowing gas. The 2/2 intrinsic MgII systems have outflow velocities a factor of $\\sim4$ higher than the NaID outflow velocities. Our results are consistent with AGN-driven outflows destroying the cool gas within their halos, which dramatically decreases their cool gas covering fraction, while star-burst driven winds are expelling cool gas into their circumgalactic media (CGM). This picture appears contrary to quasar--quasar pair studies which show that the quasar CGM contains significant amounts of cool gas whereas intrinsic gas found `down-the-barrel' of quasars reveals no cool gas. We discuss how these results are complementary and provide support for the AGN unified model.

  13. From heavy nuclei to super-heavy nuclei

    CERN Document Server

    Theisen, C

    2003-01-01

    The existence of super-heavy nuclei has been predicted nearly fifty years ago. Due to the strong coulomb repulsion, the stabilisation of these nuclei is possible only through shell effects. The reasons for this fragile stability, as well as the theoretical predictions concerning the position of the island of stability are presented in the first part of this lecture. In the second part, experiments and experimental techniques which have been used to synthesize or search for super-heavy elements are described. Spectroscopic studies performed in very heavy elements are presented in the following section. We close this lecture with techniques that are currently being developed in order to reach the superheavy island and to study the structure of very-heavy nuclei.

  14. Hybrid radiator cooling system

    Science.gov (United States)

    France, David M.; Smith, David S.; Yu, Wenhua; Routbort, Jules L.

    2016-03-15

    A method and hybrid radiator-cooling apparatus for implementing enhanced radiator-cooling are provided. The hybrid radiator-cooling apparatus includes an air-side finned surface for air cooling; an elongated vertically extending surface extending outwardly from the air-side finned surface on a downstream air-side of the hybrid radiator; and a water supply for selectively providing evaporative cooling with water flow by gravity on the elongated vertically extending surface.

  15. Communication: Thermodynamics of stacking disorder in ice nuclei

    Science.gov (United States)

    Quigley, D.

    2014-09-01

    A simple Ising-like model for the stacking thermodynamics of ice 1 is constructed for nuclei in supercooled water, and combined with classical nucleation theory. For relative stabilities of cubic and hexagonal ice I within the range of experimental estimates, this predicts critical nuclei are stacking disordered at strong sub-cooling, consistent with recent experiments. At higher temperatures nucleation of pure hexagonal ice is recovered. Lattice-switching Monte-Carlo is applied to accurately compute the relative stability of cubic and hexagonal ice for the popular mW model of water. Results demonstrate that this model fails to adequately capture the relative energetics of the two polytypes, leading to stacking disorder at all temperatures.

  16. Photodissociation of neutron deficient nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Sonnabend, K.; Babilon, M.; Hasper, J.; Mueller, S.; Zarza, M.; Zilges, A. [TU Darmstadt, Institut fuer Kernphysik, Darmstadt (Germany)

    2006-03-15

    The knowledge of the cross sections for photodissociation reactions like e.g. ({gamma}, n) of neutron deficient nuclei is of crucial interest for network calculations predicting the abundances of the so-called p nuclei. However, only single cross sections have been measured up to now, i.e., one has to rely nearly fully on theoretical predictions. While the cross sections of stable isotopes are accessible by experiments using real photons, the bulk of the involved reactions starts from unstable nuclei. Coulomb dissociation (CD) experiments in inverse kinematics might be a key to expand the experimental database for p-process network calculations. The approach to test the accuracy of the CD method is explained. (orig.)

  17. Studies of exotic light nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Cerny, J.

    1976-05-01

    For neutron-deficient nuclei, extension of the T/sub z/ = --3/2 series of strong beta-delayed proton precursors to /sup 61/Ge is discussed. For neutron-excess nuclei, heavy-ion induced, multi-nucleon transfer reaction studies of masses and energy levels of 2sld shell nuclei with T/sub z/ greater than or equal to 5/2 are covered. In addition, preliminary attempts to employ the (/sup 7/Li,/sup 2/He) reaction for the latter studies are shown; a new detection system capable of observing unbound final states as reaction products is demonstrated via investigations of the (..cap alpha..,/sup 2/He) reaction.

  18. A relativistic symmetry in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Ginocchio, J N [MS B283, Theoretical Division, Los Alamos National Laboratory Los Alamos, New Mexico 87545 (Mexico)

    2007-11-15

    We review some of the empirical and theoretical evidence supporting pseudospin symmetry in nuclei as a relativistic symmetry. We review the case that the eigenfunctions of realistic relativistic nuclear mean fields approximately conserve pseudospin symmetry in nuclei. We discuss the implications of pseudospin symmetry for magnetic dipole transitions and Gamow-Teller transitions between states in pseudospin doublets. We explore a more fundamental rationale for pseudospin symmetry in terms of quantum chromodynamics (QCD), the basic theory of the strong interactions. We show that pseudospin symmetry in nuclei implies spin symmetry for an anti-nucleon in a nuclear environment. We also discuss the future and what role pseudospin symmetry may be expected to play in an effective field theory of nucleons.

  19. Photoproduction of mesons off nuclei

    CERN Document Server

    Krusche, B

    2011-01-01

    Recent results for the photoproduction of mesons off nuclei are reviewed. These experiments have been performed for two major lines of research related to the properties of the strong interaction. The investigation of nucleon resonances requires light nuclei as targets for the extraction of the isospin composition of the electromagnetic excitations. This is done with quasi-free meson photoproduction off the bound neutron and supplemented with the measurement of coherent photoproduction reactions, serving as spin and/or isospin filters. Furthermore, photoproduction from light and heavy nuclei is a very efficient tool for the study of the interactions of mesons with nuclear matter and the in-medium properties of hadrons. Experiments are currently rapidly developing due to the combination of high quality tagged (and polarized) photon beams with state-of-the-art 4pi detectors and polarized targets.

  20. Spontaneous fission of superheavy nuclei

    Indian Academy of Sciences (India)

    R A Gherghescu; D N Poenaru

    2015-09-01

    The macroscopic–microscopic method is extended to calculate the deformation energy and penetrability for binary nuclear configurations typical for fission processes. The deformed two-centre shell model is used to obtain single-particle energy levels for the transition region of two partially overlapped daughter and emitted fragment nuclei. The macroscopic part is obtained using the Yukawa-plus-exponential potential. The microscopic shell and pairing corrections are obtained using the Strutinsky and BCS approaches and the cranking formulae yield the inertia tensor. Finally, the WKB method is used to calculate penetrabilities and spontaneous fission half-lives. Calculations are performed for the decay of 282,292120 nuclei.

  1. Octupole shapes in heavy nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, I.

    1994-08-01

    Theoretical calculations and measurements show the presence of strong octupole correlations in thecyround states and low-lying states of odd-mass and odd-odd nuclei in the RaPa region. Evidence for octupole correlations is provided by the observation of parity doublets and reductions in M1 matrix elements, decoupling parameters, and Coriolis matrix elements Involving high-j states. Enhancement of E1 transition rates has also been observed for some of the octupole deformed nuclei. The most convincing argument for octupole deformation is provided by the similarities of the reduced alpha decay rates to the two members of parity doublets.

  2. International Symposium on Exotic Nuclei

    CERN Document Server

    Sobolev, Yu G; EXON-2014

    2015-01-01

    The production and the properties of nuclei in extreme conditions, such as high isospin, temperature, angular momenta, large deformations etc., have become the subject of detailed investigations in all scientific centers. The main topics discussed at the Symposium were: Synthesis and Properties of Exotic Nuclei; Superheavy Elements; Rare Processes, Nuclear Reactions, Fission and Decays; Experimental Facilities and Scientific Projects. This book provides a comprehensive overview of the newest results of the investigations in the main scientific centers such as GSI (Darmstadt, Germany), GANIL (Caen, France), RIKEN (Wako-shi, Japan), MSU (Michigan, USA), and JINR (Dubna, Russia).

  3. PDFs from nucleons to nuclei

    CERN Document Server

    Accardi, Alberto

    2016-01-01

    I review recent progress in the extraction of unpolarized parton distributions in the proton and in nuclei from a unified point of view that highlights how the interplay between high energy particle physics and lower energy nuclear physics can be of mutual benefit to either field. Areas of overlap range from the search for physics beyond the standard model at the LHC, to the study of the non perturbative structure of nucleons and the emergence of nuclei from quark and gluon degrees of freedom, to the interaction of colored probes in a cold nuclear medium.

  4. Discovery of Nuclei at and Beyond the Proton Dripline

    Institute of Scientific and Technical Information of China (English)

    M. Thoennessen

    2016-01-01

    In contrast to the neutron dripline the proton dripline has been reached almost across the whole nuclear chart. However, because of the Coulomb barrier relatively long-lived isotopes can exist beyond the proton dripline. It is estimated that about 200 new isotopes at and beyond the proton dripline should be able to be discovered in the future. A brief review of the discovery of proton-rich nuclides as well as an outlook for the discovery potential in the future is presented.

  5. Partial Dynamical Symmetries in Nuclei

    CERN Document Server

    Leviatan, A

    2000-01-01

    Partial dynamical symmetries (PDS) are shown to be relevant to the interpretation of the $K=0_2$ band and to the occurrence of F-spin multiplets of ground and scissors bands in deformed nuclei. Hamiltonians with bosonic and fermionic PDS are presented.

  6. Multiphonon giant resonances in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Aumann, T. [Mainz Univ. (Germany). Inst. fuer Kernchemie; Bortignon, P.F. [Milan Univ. (Italy). Dipt. di Fisica]|[Istituto Nazionale di Fisica Nucleare, Milan (Italy); Emling, H. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany)

    1998-07-01

    We review the present knowledge of multiphonon giant resonances in nuclei. Theoretical concepts approaching the intrinsic structure and excitation mechanisms of multi-phonon states are discussed. The available experimental results are summarized, including a brief description of applied techniques. This review emphasizes electromagnetic excitations of double dipole resonances. Open questions and possible routes toward a solution are addressed. (orig.)

  7. Nuclear astrophysics of light nuclei

    DEFF Research Database (Denmark)

    Fynbo, Hans Otto Uldall

    2013-01-01

    A review of nuclear astrophysics of light nuclei using radioactive beams or techniques developed for radioactive beams is given. We discuss Big Bang nucleosynthesis, with special focus on the lithium problem, aspects of neutrino-physics, helium-burning and finally selected examples of studies...

  8. Fission dynamics of hot nuclei

    Indian Academy of Sciences (India)

    Santanu Pal; Jhilam Sadhukhan

    2014-04-01

    Experimental evidence accumulated during the last two decades indicates that the fission of excited heavy nuclei involves a dissipative dynamical process. We shall briefly review the relevant dynamical model, namely the Langevin equations for fission. Statistical model predictions using the Kramers’ fission width will also be discussed.

  9. Low energy + scattering on = nuclei

    Indian Academy of Sciences (India)

    Swapan Das; Arun K Jain

    2003-11-01

    The data for the total cross-section of + scattering on various nuclei have been analysed in the Glauber multiple scattering theory. Energy-dependent +-nucleus optical potential is generated using the forward +-nucleon scattering amplitude and the nuclear density distribution. Along with this, the calculated total +-nucleus cross-sections using the effective +-nucleon cross-section inside the nucleus are also presented.

  10. Liquid-Cooled Garment

    Science.gov (United States)

    1977-01-01

    A liquid-cooled bra, offshoot of Apollo moon suit technology, aids the cancer-detection technique known as infrared thermography. Water flowing through tubes in the bra cools the skin surface to improve resolution of thermograph image.

  11. Mechanical Feedback from Active Galactic Nuclei in Galaxies, Groups, and Clusters

    CERN Document Server

    McNamara, B R

    2012-01-01

    The radiative cooling timescales at the centers of hot atmospheres surrounding elliptical galaxies, groups, and clusters are much shorter than their ages. Therefore, hot atmospheres are expected to cool and to form stars. Cold gas and star formation are observed in central cluster galaxies but at levels below those expected from an unimpeded cooling flow. X-ray observations have shown that wholesale cooling is being offset by mechanical heating from radio active galactic nuclei. Feedback is widely considered to be an important and perhaps unavoidable consequence of the evolution of galaxies and supermassive black holes. We show that cooling X-ray atmospheres and the ensuing star formation and nuclear activity are probably coupled to a self-regulated feedback loop. While the energetics are now reasonably well understood, other aspects of feedback are not. We highlight the problems of atmospheric heating and transport processes, accretion, and nuclear activity, and we discuss the potential role of black hole sp...

  12. Data center cooling system

    Energy Technology Data Exchange (ETDEWEB)

    Chainer, Timothy J; Dang, Hien P; Parida, Pritish R; Schultz, Mark D; Sharma, Arun

    2015-03-17

    A data center cooling system may include heat transfer equipment to cool a liquid coolant without vapor compression refrigeration, and the liquid coolant is used on a liquid cooled information technology equipment rack housed in the data center. The system may also include a controller-apparatus to regulate the liquid coolant flow to the liquid cooled information technology equipment rack through a range of liquid coolant flow values based upon information technology equipment temperature thresholds.

  13. Stochastic cooling in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Brennan,J.M.; Blaskiewicz, M. M.; Severino, F.

    2009-05-04

    After the success of longitudinal stochastic cooling of bunched heavy ion beam in RHIC, transverse stochastic cooling in the vertical plane of Yellow ring was installed and is being commissioned with proton beam. This report presents the status of the effort and gives an estimate, based on simulation, of the RHIC luminosity with stochastic cooling in all planes.

  14. Cooling, AGN Feedback and Star Formation in Simulated Cool-Core Galaxy Clusters

    CERN Document Server

    Li, Yuan; Ruszkowski, Mateusz; Voit, G Mark; O'Shea, Brian W; Donahue, Megan

    2015-01-01

    Numerical simulations of active galactic nuclei (AGN) feedback in cool-core galaxy clusters have successfully avoided classical cooling flows, but often produce too much cold gas. We perform adaptive mesh simulations that include momentum-driven AGN feedback, self-gravity, star formation and stellar feedback, focusing on the interplay between cooling, AGN heating and star formation in an isolated cool-core cluster. Cold clumps triggered by AGN jets and turbulence form filamentary structures tens of kpc long. This cold gas feeds both star formation and the supermassive black hole (SMBH), triggering an AGN outburst that increases the entropy of the ICM and reduces its cooling rate. Within 1-2 Gyr, star formation completely consumes the cold gas, leading to a brief shutoff of the AGN. The ICM quickly cools and redevelops multiphase gas, followed by another cycle of star formation/AGN outburst. Within 6.5 Gyr, we observe three such cycles. There is good agreement between our simulated cluster and the observations...

  15. Laser cooling of solids

    OpenAIRE

    Nemova, Galina

    2009-01-01

    Parallel to advances in laser cooling of atoms and ions in dilute gas phase, which has progressed immensely, resulting in physics Nobel prizes in 1997 and 2001, major progress has recently been made in laser cooling of solids. I compare the physical nature of the laser cooling of atoms and ions with that of the laser cooling of solids. I point out all advantages of this new and very promising area of laser physics. Laser cooling of solids (optical refrigeration) at the present time can be lar...

  16. What Kinds of Accretion Disks Are There in the Nuclei of Radio Galaxies?

    CERN Document Server

    Kaburaki, Osamu; Tamura, Naoya; Wajima, Kiyoaki

    2010-01-01

    It seems to be a widely accepted opinion that the types of accretion disks (or flows) generally realized in the nuclei of radio galaxies and in further lower mass-accretion rate nuclei are inner, hot, optically thin, radiatively inefficient accretion flows (RIAFs) surrounded by outer, cool, optically thick, standard type accretion disks. However, observational evidence for the existence of such outer cool disks in these nuclei is rather poor. Instead, recent observations sometimes suggest the existence of inner cool disks of non-standard type, which develop in the region very close to their central black holes. Taking NGC 4261 as a typical example of such light eating nuclei, for which both flux data ranging from radio to X-ray and data for the counterjet occultation are available, we examine the plausibility of such a picture for the accretion states as mentioned above, based on model predictions. It is shown that the explanation of the gap seen in the counterjet emission in terms of the free-free absorption...

  17. Scissors Mode in Gd Nuclei

    Directory of Open Access Journals (Sweden)

    Wu C.Y.

    2012-02-01

    Full Text Available Spectra of γ rays following neutron capture at isolated resonances of 6 stable Gd isotopes were measured with highly segmented BaF2 detector DANCE at the Los Alamos LANSCE spallation neutron source. The main emphasis was put on studying the γ-cascade decay of neutron resonances to get unique information on photon strength. An analysis of the accumulated γ-ray spectra within the extreme statistical model leads to an inescapable conclusion that scissors mode resonances are built not only on the ground-state, but also on excited levels in all product nuclei studied. The results on summed B(M1↑ strength and energy of the scissors mode are compared with systematics of scissors mode parameters for the ground-state transitions deduced from nuclear resonance fluorescence measurements. A specific feature of our experiments is the investigation of scissors mode of odd nuclei, for which the nuclear resonance fluorescence provides only limited information.

  18. Scissors Mode in Gd Nuclei

    Science.gov (United States)

    Kroll, J.; Baramsai, B.; Becker, J. A.; Bečvář, F.; Bredeweg, T. A.; Couture, A.; Chyzh, A.; Dashdorj, D.; Haight, R. C.; Jandel, M.; Krtička, M.; Mitchell, G. E.; O'Donnell, J. M.; Parker, W.; Rundberg, R. S.; Ullmann, J. L.; Vieira, G. J.; Walker, C. L.; Wilhelmy, J. B.; Wouters, J. M.; Wu, C. Y.

    2012-02-01

    Spectra of γ rays following neutron capture at isolated resonances of 6 stable Gd isotopes were measured with highly segmented BaF2 detector DANCE at the Los Alamos LANSCE spallation neutron source. The main emphasis was put on studying the γ-cascade decay of neutron resonances to get unique information on photon strength. An analysis of the accumulated γ-ray spectra within the extreme statistical model leads to an inescapable conclusion that scissors mode resonances are built not only on the ground-state, but also on excited levels in all product nuclei studied. The results on summed B(M1)↑ strength and energy of the scissors mode are compared with systematics of scissors mode parameters for the ground-state transitions deduced from nuclear resonance fluorescence measurements. A specific feature of our experiments is the investigation of scissors mode of odd nuclei, for which the nuclear resonance fluorescence provides only limited information.

  19. Evolution of active galactic nuclei

    CERN Document Server

    Merloni, Andrea

    2012-01-01

    [Abriged] Supermassive black holes (SMBH) lurk in the nuclei of most massive galaxies, perhaps in all of them. The tight observed scaling relations between SMBH masses and structural properties of their host spheroids likely indicate that the processes fostering the growth of both components are physically linked, despite the many orders of magnitude difference in their physical size. This chapter discusses how we constrain the evolution of SMBH, probed by their actively growing phases, when they shine as active galactic nuclei (AGN) with luminosities often in excess of that of the entire stellar population of their host galaxies. Following loosely the chronological developments of the field, we begin by discussing early evolutionary studies, when AGN represented beacons of light probing the most distant reaches of the universe and were used as tracers of the large scale structure. This early study turned into AGN "Demography", once it was realized that the strong evolution (in luminosity, number density) of ...

  20. Proton scattering from unstable nuclei

    Indian Academy of Sciences (India)

    Y Blumenfeld; E Khan; F Maréchal; T Suomijärvi

    2001-08-01

    Recent improvements in the intensities and optical qualities of radioactive beams have made possible the study of elastic and inelastic proton scattering on unstable nuclei. The design and performances of an innovative silicon strip detector array devoted to such experiments are described. The quality of the data obtained are illustrated with recent results obtained at the GANIL facility for unstable oxygen, sulfur and argon isotopes. Methods to analyse the data using phenomenological and microscopic optical model potentials are discussed.

  1. Strange neutral currents in nuclei

    CERN Document Server

    Ressell, M T; Aufderheide, M B; Bloom, S D; Resler, D A

    1995-01-01

    We examine the effects on the nuclear neutral current Gamow-Teller (GT) strength of a finite contribution from a polarized strange quark sea. We perform nuclear shell model calculations of the neutral current GT strength for a number of nuclei likely to be present during stellar core collapse. We compare the GT strength when a finite strange quark contribution is included to the strength without such a contribution. As an example, the process of neutral current nuclear de-excitation via \

  2. Weak pion production from nuclei

    Indian Academy of Sciences (India)

    S K Singh; M Sajjad Athar; Shakeb Ahmad

    2006-04-01

    The charged current pion production induced by neutrinos in 12C, 16O and 56Fe nuclei has been studied. The calculations have been done for the coherent as well as the incoherent processes assuming dominance and takes into account the effect of Pauli blocking, Fermi motion and the renormalization of in the nuclear medium. The pion absorption effects have also been taken into account.

  3. Triaxial rotation in atomic nuclei

    Institute of Scientific and Technical Information of China (English)

    CHEN Yong-Shou; GAO Zao-Chun

    2009-01-01

    The Projected Shell Model has been developed to include the spontaneously broken axial symmetry so that the rapidly rotating triaxial nuclei can be described microscopically. The theory provides an useful tool to gain an insight into how a triaxial nucleus rotates, a fundamental question in nuclear structure. We shall address some current interests that are strongly associated with the triaxial rotation. A feasible method to explore the problem has been suggested.

  4. Double pion photoproduction in nuclei

    CERN Document Server

    Vicente-Vacas, M J; Gómez-Tejedor, J A; Vicente-Vacas, M J; Oset, E; Gómez Tejedor, J A

    1994-01-01

    Abstract: The inclusive A(gamma,pi+ pi-)X reaction is studied theoretically. A sizeable enhancement of the cross section is found, in comparison with the scaling of the deuteron cross section (sigma_deuteron * A/2). This enhancement is due to the modifications in the nuclear medium of the gamma N ----> pi pi N amplitude and the pion dispersion relation. The enhancement is found to be bigger than the one already observed in the (pi,pi pi) reaction in nuclei.

  5. Continuum spectroscopy of light nuclei

    Directory of Open Access Journals (Sweden)

    Charity R. J.

    2016-01-01

    Full Text Available Resonance spectroscopy of light nuclei is discussed with emphasis on the invariant-mass measurements performed with the HiRA detector. For three-body exit channels, we consider the exact conditions necessary such that the decay can be described as either sequential or prompt. However experimentally, we find some cases where the decay is intermediate between these two limits. Finally, two-proton decay from isobaric analog states is discussed.

  6. Geometric symmetries in light nuclei

    CERN Document Server

    Bijker, Roelof

    2016-01-01

    The algebraic cluster model is is applied to study cluster states in the nuclei 12C and 16O. The observed level sequences can be understood in terms of the underlying discrete symmetry that characterizes the geometrical configuration of the alpha-particles, i.e. an equilateral triangle for 12C, and a regular tetrahedron for 16O. The structure of rotational bands provides a fingerprint of the underlying geometrical configuration of alpha-particles.

  7. Stochastic cooling in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Brennan J. M.; Blaskiewicz, M.; Mernick, K.

    2012-05-20

    The full 6-dimensional [x,x'; y,y'; z,z'] stochastic cooling system for RHIC was completed and operational for the FY12 Uranium-Uranium collider run. Cooling enhances the integrated luminosity of the Uranium collisions by a factor of 5, primarily by reducing the transverse emittances but also by cooling in the longitudinal plane to preserve the bunch length. The components have been deployed incrementally over the past several runs, beginning with longitudinal cooling, then cooling in the vertical planes but multiplexed between the Yellow and Blue rings, next cooling both rings simultaneously in vertical (the horizontal plane was cooled by betatron coupling), and now simultaneous horizontal cooling has been commissioned. The system operated between 5 and 9 GHz and with 3 x 10{sup 8} Uranium ions per bunch and produces a cooling half-time of approximately 20 minutes. The ultimate emittance is determined by the balance between cooling and emittance growth from Intra-Beam Scattering. Specific details of the apparatus and mathematical techniques for calculating its performance have been published elsewhere. Here we report on: the method of operation, results with beam, and comparison of results to simulations.

  8. Cooling by Thermodynamic Induction

    Science.gov (United States)

    Patitsas, S. N.

    2017-03-01

    A method is described for cooling conductive channels to below ambient temperature. The thermodynamic induction principle dictates that the electrically biased channel will cool if the electrical conductance decreases with temperature. The extent of this cooling is calculated in detail for both cases of ballistic and conventional transport with specific calculations for carbon nanotubes and conventional metals, followed by discussions for semiconductors, graphene, and metal-insulator transition systems. A theorem is established for ballistic transport stating that net cooling is not possible. For conventional transport, net cooling is possible over a broad temperature range, with the range being size-dependent. A temperature clamping scheme for establishing a metastable nonequilibrium stationary state is detailed and followed with discussion of possible applications to on-chip thermoelectric cooling in integrated circuitry and quantum computer systems.

  9. Cooling by Thermodynamic Induction

    Science.gov (United States)

    Patitsas, S. N.

    2016-11-01

    A method is described for cooling conductive channels to below ambient temperature. The thermodynamic induction principle dictates that the electrically biased channel will cool if the electrical conductance decreases with temperature. The extent of this cooling is calculated in detail for both cases of ballistic and conventional transport with specific calculations for carbon nanotubes and conventional metals, followed by discussions for semiconductors, graphene, and metal-insulator transition systems. A theorem is established for ballistic transport stating that net cooling is not possible. For conventional transport, net cooling is possible over a broad temperature range, with the range being size-dependent. A temperature clamping scheme for establishing a metastable nonequilibrium stationary state is detailed and followed with discussion of possible applications to on-chip thermoelectric cooling in integrated circuitry and quantum computer systems.

  10. Radiant Floor Cooling Systems

    DEFF Research Database (Denmark)

    Olesen, Bjarne W.

    2008-01-01

    In many countries, hydronic radiant floor systems are widely used for heating all types of buildings such as residential, churches, gymnasiums, hospitals, hangars, storage buildings, industrial buildings, and smaller offices. However, few systems are used for cooling.This article describes a floor...... cooling system that includes such considerations as thermal comfort of the occupants, which design parameters will influence the cooling capacity and how the system should be controlled. Examples of applications are presented....

  11. Initial Cooling Experiment (ICE)

    CERN Multimedia

    Photographic Service

    1978-01-01

    In 1977, in a record-time of 9 months, the magnets of the g-2 experiment were modified and used to build a proton/antiproton storage ring: the "Initial Cooling Experiment" (ICE). It served for the verification of the cooling methods to be used for the "Antiproton Project". Stochastic cooling was proven the same year, electron cooling followed later. Also, with ICE the experimental lower limit for the antiproton lifetime was raised by 9 orders of magnitude: from 2 microseconds to 32 hours. For its previous life as g-2 storage ring, see 7405430. More on ICE: 7711282, 7809081, 7908242.

  12. High energy electron cooling

    Energy Technology Data Exchange (ETDEWEB)

    Parkhomchuk, V. [Budker Institute of Nuclear Physics, Novosibirsk (Russian Federation)

    1997-09-01

    High energy electron cooling requires a very cold electron beam. The questions of using electron cooling with and without a magnetic field are presented for discussion at this workshop. The electron cooling method was suggested by G. Budker in the middle sixties. The original idea of the electron cooling was published in 1966. The design activities for the NAP-M project was started in November 1971 and the first run using a proton beam occurred in September 1973. The first experiment with both electron and proton beams was started in May 1974. In this experiment good result was achieved very close to theoretical prediction for a usual two component plasma heat exchange.

  13. Power electronics cooling apparatus

    Science.gov (United States)

    Sanger, Philip Albert; Lindberg, Frank A.; Garcen, Walter

    2000-01-01

    A semiconductor cooling arrangement wherein a semiconductor is affixed to a thermally and electrically conducting carrier such as by brazing. The coefficient of thermal expansion of the semiconductor and carrier are closely matched to one another so that during operation they will not be overstressed mechanically due to thermal cycling. Electrical connection is made to the semiconductor and carrier, and a porous metal heat exchanger is thermally connected to the carrier. The heat exchanger is positioned within an electrically insulating cooling assembly having cooling oil flowing therethrough. The arrangement is particularly well adapted for the cooling of high power switching elements in a power bridge.

  14. Tensor Effect on Bubble Nuclei

    Institute of Scientific and Technical Information of China (English)

    WANG Yan-Zhao; GU Jian-Zhong; ZHANG Xi-Zhen; DONG Jian-Min

    2011-01-01

    In the framework of the Hartree-Fock-Bogoliubov (HFB) approach with Skyrme interactions SLy5+T, SLy5+Tw and several sets of TIJ parametrizations, I.e. The Skyrme interaction parametrizations including the tensor terms, the proton density distribution in 34Si and 46Ar nuclei is calculated with and without the tensor force. It is shown that the bubble effect in 34Si does not depend a great deal on the Skyrme parametrization and the proton density distribution in 34Si is hardly influenced by the tensor force. As to 46Ar, the SLy5+Tw parametrization favors the formation of the bubble structure due to the inversion between the 2s1/2 and 1d3/2 orbits (2s1/2-ld3/2 inversion). The inversion mechanism induced by the SLy5+Tw interaction is analyzed based on the proton single-particle spectra obtained from the SLy5 and SLy5+Tw interactions as well as the wave functions of the 2s1/2 and 1d3/2 states.%In the framework of the Hartree-Fock-Bogoliubov (HFB) approach with Skyrme interactions SLy5+ T,SLy5+ Tω and several sets of TIJ parametrizations,i.e.the Skyrme interaction pararmetrizations including the tensor terms,the proton density distribution in 34Si and 46 Ar nuclei is calculated with and without the tensor force.It is shown that the bubble effect in 34Si does not depend a great deal on the Skyrme parametrization and the proton density distribution in 34Si is hardly influenced by the tensor force.As to 46Ar,the SLy5+ Tω parametrization favors the formation of the bubble structure due to the inversion between the 2s1/2 and 1d3/2 orbits (2s1/2-1d3/2 inversion).The inversion mechanism induced by the SLy5+ Tω interaction is analyzed based on the proton single-particle spectra obtained from the SLy5 and SLy5+ Tω interactions as well as the wave functions of the 2s1/2 and 1d3/2 states.The study of exotic nuclear structures has been a hot topic in nuclear physics.[1-4] Exotic nuclei are unstabile,superheavy nuclei,halo nuclei and so forth,whose structures are quite different

  15. New experimental method to study the collective modes in exotic nuclei; influence of the superfluidity on the cooling time of a neutron star; Nouvelle methode experimentale dediee a l'etude des modes collectifs dans les noyaux exotiques; influence de la superfluidite sur le temps de refroidissement d'une etoile a neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Monrozeau, Ch

    2007-07-15

    Giant monopole (GMR) and quadrupole (GQR) resonances have been measured in the {sup 56}Ni using inelastic scattering of 50 A.MeV deuteron at the Grand Accelerateur National d'Ions Lourds facility. This is the first experimental observation of isoscalar collective modes in a short-lived nucleus. The secondary beam was impinged on the active target Maya filled with a pure deuterium gas. Recoiling deuterons were detected in Maya and in a wall of nine silicon detectors. The GMR and GQR are centered at 19.3(0.5) and 16.2(0.5) MeV, respectively. Corresponding angular distributions were extracted from 3 to 7 degrees in the centre of mass frame. DWBA analysis based on RPA transition densities yields the percentage of the energy weighted sum rule exhausted: 136(27) % for the GMR et 76(13) % for the GQR. A finite temperature Hartree-Fock-Bogoliubov model was implemented to describe the 10 Wigner-Seitz cells which compose the inner crust of neutron stars and to microscopically calculate their specific heat. Calculations are performed with two contact pairing forces chosen to simulate the pairing properties of uniform neutron matter corresponding to the BCS approximation and to polarisation effects. Under the assumption of a rapid cooling of the core and an initial temperature of 100 keV in the inner crust, the cooling time of the star was estimated at 9 and 34 years, respectively. (author)

  16. Microscopic properties of superdeformed nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Karlsson, Lennart B

    1999-04-01

    Many high spin rotational bands in superdeformed nuclei have been found in the A 140 - 150 region, but so far no linking transitions to known normal-deformed states have been found in these nuclei. Therefore, configuration and spin assignments have to be based on indirect spectroscopic information. Identical bands were first discovered in this region of superdeformed states. At present, some identical bands have also been found at normal deformation, but such bands are more common at superdeformation. Recently lifetime measurements have given relative quadrupole moments with high accuracy. Spectroscopic quantities are calculated using the configuration constrained cranked Nilsson-Strutinsky model with the modified oscillator potential. In a statistical study the occurrence of identical bands is tested. Comparing superdeformed and normal deformed nuclei, the higher possibility for identical bands at superdeformation is understood from calculated reduced widths of the E{sub {gamma}} and J{sup (2)} distributions. The importance of high-N orbitals for identical bands is also discussed. Additivity of electric quadrupole moment contributions in the superdeformed A - 150 region is discussed with the nucleus {sup 152}Dy as a `core`. In analytic harmonic oscillator calculations, the effective electric quadrupole moment q{sub eff}, i.e. the change in the total quadrupole moment caused by the added particle, is expressed as a simple function of the single-particle mass, quadrupole moment q{sub {nu}}. Also in realistic calculations, simple relations between q{sub eff} and q{sub {nu}} can be used to estimate the total electric quadrupole moment, e.g. for the nucleus {sup 142}Sm, by adding the effect of 10 holes, to the total electric quadrupole moment of {sup 152}Dy. Furthermore, tools are given for estimating the quadrupole moment for possible configurations in the superdeformed A - 150 region. For the superdeformed region around {sup 143}Eu, configuration and spin assignments

  17. Breakup Densities of Hot Nuclei.

    Science.gov (United States)

    Viola, Vic

    2006-04-01

    Breakup densities of hot ^197Au-like residues have been deduced from the systematic trends of Coulomb parameters required to fit intermediate-mass-fragment kinetic-energy spectra. The results indicate emission from nuclei near normal nuclear density below an excitation energy E*/A .3ex˜x 5 MeV. Temperatures derived from these data with a density-dependent Fermi-gas model yield a nuclear caloric curve that is generally consistent with those derived from isotope ratios.

  18. Double pion photoproduction in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Gomez Tejedor, J.A. [Departamento de Fisica Teorica, Valencia (Spain); Vicente-Vacas, M.J. [Departamento de Fisica Teorica, Valencia (Spain); Oset, E. [Departamento de Fisica Teorica, Valencia (Spain)

    1995-06-19

    The inclusive A({gamma},{pi}{sup +}{pi}{sup -})X reaction is studied theoretically. A sizable enhancement of the cross section is found, in comparison with the scaling of the deuteron cross section ({sigma}{sub d} A/2). This enhancement is due to the modifications in the nuclear medium of the {gamma}N {yields}{pi}{pi}N amplitude and the pion dispersion relation. The enhancement is found to be bigger than the one already observed in the ({pi},{pi}{pi}) reaction in nuclei. ((orig.)).

  19. Pairing correlations in exotic nuclei

    CERN Document Server

    Sagawa, H

    2012-01-01

    The BCS and HFB theories which can accommodate the pairing correlations in the ground states of atomic nuclei are presented. As an application of the pairing theories, we investigate the spatial extension of weakly bound Ne and C isotopes by taking into account the pairing correlation with the Hartree-Fock-Bogoliubov (HFB) method and a 3-body model, respectively. We show that the odd-even staggering in the reaction cross sections of $^{30,31,32}$Ne and $^{14,15,16}$C are successfully reproduced, and thus the staggering can be attributed to the unique role of pairing correlations in nuclei far from the stability line. A correlation between a one-neutron separation energy and the anti-halo effect is demonstrated for $s$- and p-waves using the HFB wave functions. We also propose effective density-dependent pairing interactions which reproduce both the neutron-neutron ($nn$) scattering length at zero density and the neutron pairing gap in uniform matter. Then, we apply these interactions to study pairing gaps in ...

  20. Selfconsistent calculations for hyperdeformed nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Molique, H.; Dobaczewski, J.; Dudek, J.; Luo, W.D. [Universite Louis Pasteur, Strasbourg (France)

    1996-12-31

    Properties of the hyperdeformed nuclei in the A {approximately} 170 mass range are re-examined using the self-consistent Hartree-Fock method with the SOP parametrization. A comparison with the previous predictions that were based on a non-selfconsistent approach is made. The existence of the {open_quotes}hyper-deformed shell closures{close_quotes} at the proton and neutron numbers Z=70 and N=100 and their very weak dependence on the rotational frequency is suggested; the corresponding single-particle energy gaps are predicted to play a role similar to that of the Z=66 and N=86 gaps in the super-deformed nuclei of the A {approximately} 150 mass range. Selfconsistent calculations suggest also that the A {approximately} 170 hyperdeformed structures have neglegible mass asymmetry in their shapes. Very importantly for the experimental studies, both the fission barriers and the {open_quotes}inner{close_quotes} barriers (that separate the hyperdeformed structures from those with smaller deformations) are predicted to be relatively high, up to the factor of {approximately}2 higher than the corresponding ones in the {sup 152}Dy superdeformed nucleus used as a reference.

  1. Thermal instability of cell nuclei

    Science.gov (United States)

    Warmt, Enrico; Kießling, Tobias R.; Stange, Roland; Fritsch, Anatol W.; Zink, Mareike; Käs, Josef A.

    2014-07-01

    DNA is known to be a mechanically and thermally stable structure. In its double stranded form it is densely packed within the cell nucleus and is thermo-resistant up to 70\\:^\\circ {\\rm{C}}. In contrast, we found a sudden loss of cell nuclei integrity at relatively moderate temperatures ranging from 45 to 55\\:^\\circ {\\rm{C}}. In our study, suspended cells held in an optical double beam trap were heated under controlled conditions while monitoring the nuclear shape. At specific critical temperatures, an irreversible sudden shape transition of the nuclei was observed. These temperature induced transitions differ in abundance and intensity for various normal and cancerous epithelial breast cells, which clearly characterizes different cell types. Our results show that temperatures slightly higher than physiological conditions are able to induce instabilities of nuclear structures, eventually leading to cell death. This is a surprising finding since recent thermorheological cell studies have shown that cells have a lower viscosity and are thus more deformable upon temperature increase. Since the nucleus is tightly coupled to the outer cell shape via the cytoskeleton, the force propagation of nuclear reshaping to the cell membrane was investigated in combination with the application of cytoskeletal drugs.

  2. Elastocaloric cooling: Stretch to actively cool

    Science.gov (United States)

    Ossmer, Hinnerk; Kohl, Manfred

    2016-10-01

    The elastocaloric effect can be exploited in solid-state cooling technologies as an alternative to conventional vapour compression. Now, an elastocaloric device based on the concept of active regeneration achieves a temperature lift of 15.3 K and efficiencies competitive with other caloric-based approaches.

  3. Measure Guideline: Ventilation Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Springer, D.; Dakin, B.; German, A.

    2012-04-01

    The purpose of this measure guideline on ventilation cooling is to provide information on a cost-effective solution for reducing cooling system energy and demand in homes located in hot-dry and cold-dry climates. This guideline provides a prescriptive approach that outlines qualification criteria, selection considerations, and design and installation procedures.

  4. The final cool down

    CERN Multimedia

    Thursday 29th May, the cool-down of the final sector (sector 4-5) of LHC has begun, one week after the start of the cool-down of sector 1-2. It will take five weeks for the sectors to be cooled from room temperature to 5 K and a further two weeks to complete the cool down to 1.9 K and the commissioning of cryogenic instrumentation, as well as to fine tune the cryogenic plants and the cooling loops of cryostats.Nearly a year and half has passed since sector 7-8 was cooled for the first time in January 2007. For Laurent Tavian, AT/CRG Group Leader, reaching the final phase of the cool down is an important milestone, confirming the basic design of the cryogenic system and the ability to operate complete sectors. “All the sectors have to operate at the same time otherwise we cannot inject the beam into the machine. The stability and reliability of the cryogenic system and its utilities are now very important. That will be the new challenge for the coming months,” he explains. The status of the cool down of ...

  5. Solar absorption cooling

    NARCIS (Netherlands)

    Kim, D.-S.

    2007-01-01

    As the world concerns more and more on global climate changes and depleting energy resources, solar cooling technology receives increasing interests from the public as an environment-friendly and sustainable alternative. However, making a competitive solar cooling machine for the market still

  6. Passive evaporative cooling

    NARCIS (Netherlands)

    Tzoulis, A.

    2011-01-01

    This "designers' manual" is made during the TIDO-course AR0531 Smart & Bioclimatic Design. Passive techniques for cooling are a great way to cope with the energy problem of the present day. This manual introduces passive cooling by evaporation. These methods have been used for many years in traditi

  7. Data center cooling method

    Energy Technology Data Exchange (ETDEWEB)

    Chainer, Timothy J.; Dang, Hien P.; Parida, Pritish R.; Schultz, Mark D.; Sharma, Arun

    2015-08-11

    A method aspect for removing heat from a data center may use liquid coolant cooled without vapor compression refrigeration on a liquid cooled information technology equipment rack. The method may also include regulating liquid coolant flow to the data center through a range of liquid coolant flow values with a controller-apparatus based upon information technology equipment temperature threshold of the data center.

  8. Liquid Cooled Garments

    Science.gov (United States)

    1979-01-01

    Astronauts working on the surface of the moon had to wear liquid-cooled garments under their space suits as protection from lunar temperatures which sometimes reach 250 degrees Fahrenheit. In community service projects conducted by NASA's Ames Research Center, the technology developed for astronaut needs has been adapted to portable cooling systems which will permit two youngsters to lead more normal lives.

  9. Solar absorption cooling

    NARCIS (Netherlands)

    Kim, D.-S.

    2007-01-01

    As the world concerns more and more on global climate changes and depleting energy resources, solar cooling technology receives increasing interests from the public as an environment-friendly and sustainable alternative. However, making a competitive solar cooling machine for the market still remain

  10. Coherent electron cooling

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko,V.

    2009-05-04

    Cooling intense high-energy hadron beams remains a major challenge in modern accelerator physics. Synchrotron radiation is still too feeble, while the efficiency of two other cooling methods, stochastic and electron, falls rapidly either at high bunch intensities (i.e. stochastic of protons) or at high energies (e-cooling). In this talk a specific scheme of a unique cooling technique, Coherent Electron Cooling, will be discussed. The idea of coherent electron cooling using electron beam instabilities was suggested by Derbenev in the early 1980s, but the scheme presented in this talk, with cooling times under an hour for 7 TeV protons in the LHC, would be possible only with present-day accelerator technology. This talk will discuss the principles and the main limitations of the Coherent Electron Cooling process. The talk will describe the main system components, based on a high-gain free electron laser driven by an energy recovery linac, and will present some numerical examples for ions and protons in RHIC and the LHC and for electron-hadron options for these colliders. BNL plans a demonstration of the idea in the near future.

  11. Excited nuclei in neutron star crusts

    CERN Document Server

    Takibayev, Nurgali; Nasirova, Diana

    2012-01-01

    The paper considers the chains of successive electron capture reactions by nuclei of the iron group which take place in the crystal structures of neutron star envelopes. It is shown that as a result of such reactions the daughter nuclei in excited states accumulate within certain layers of neutron star crusts. The phonon model of interactions is proposed between the excited nuclei in the crystalline structure, as well as formation of highly excited nuclear states which emit neutrons and higher energy photons.

  12. Modeling gasodynamic vortex cooling

    Science.gov (United States)

    Allahverdyan, A. E.; Fauve, S.

    2017-08-01

    We aim at studying gasodynamic vortex cooling in an analytically solvable, thermodynamically consistent model that can explain limitations on the cooling efficiency. To this end, we study an angular plus radial flow between two (coaxial) rotating permeable cylinders. Full account is taken of compressibility, viscosity, and heat conductivity. For a weak inward radial flow the model qualitatively describes the vortex cooling effect, in terms of both temperature and the decrease of the stagnation enthalpy, seen in short uniflow vortex (Ranque) tubes. The cooling does not result from external work and its efficiency is defined as the ratio of the lowest temperature reached adiabatically (for the given pressure gradient) to the lowest temperature actually reached. We show that for the vortex cooling the efficiency is strictly smaller than 1, but in another configuration with an outward radial flow, we find that the efficiency can be larger than 1. This is related to both the geometry and the finite heat conductivity.

  13. Hydronic rooftop cooling systems

    Science.gov (United States)

    Bourne, Richard C.; Lee, Brian Eric; Berman, Mark J.

    2008-01-29

    A roof top cooling unit has an evaporative cooling section that includes at least one evaporative module that pre-cools ventilation air and water; a condenser; a water reservoir and pump that captures and re-circulates water within the evaporative modules; a fan that exhausts air from the building and the evaporative modules and systems that refill and drain the water reservoir. The cooling unit also has a refrigerant section that includes a compressor, an expansion device, evaporator and condenser heat exchangers, and connecting refrigerant piping. Supply air components include a blower, an air filter, a cooling and/or heating coil to condition air for supply to the building, and optional dampers that, in designs that supply less than 100% outdoor air to the building, control the mixture of return and ventilation air.

  14. INITIAL COOLING EXPERIMENT (ICE)

    CERN Multimedia

    1979-01-01

    ICE was built in 1977, using the modified bending magnets of the g-2 muon storage ring (see 7405430). Its purpose was to verify the validity of stochastic and electron cooling for the antiproton project. Stochastic cooling proved a resounding success early in 1978 and the antiproton project could go ahead, now entirely based on stochastic cooling. Electron cooling was experimented with in 1979. The 26 kV equipment is housed in the cage to the left of the picture, adjacent to the "e-cooler" located in a straight section of the ring. With some modifications, the cooler was later transplanted into LEAR (Low Energy Antiproton Ring) and then, with further modifications, into the AD (Antiproton Decelerator), where it cools antiprotons to this day (2006). See also: 7711282, 7802099, 7809081.

  15. INITIAL COOLING EXPERIMENT (ICE)

    CERN Multimedia

    1978-01-01

    ICE was built in 1977, in a record time of 9 months, using the modified bending magnets of the g-2 muon storage ring. Its purpose was to verify the validity of stochastic and electron cooling for the antiproton project, to be launched in 1978. Already early in 1978, stochastic cooling proved a resounding success, such that the antiproton (p-pbar)project was entirely based on it. Tests of electron cooling followed later: protons of 46 MeV kinetic energy were cooled with an electron beam of 26 kV and 1.3 A. The cage seen prominently in the foreground houses the HV equipment, adjacent to the "cooler" installed in a straight section of the ring. With some modifications, the cooler was later transplanted into LEAR (Low Energy Antiproton Ring) and then, with further modifications, into the AD (Antiproton Decelerator), where it cools antiprotons to this day (2006). See also: 7711282, 7802099, 7908242.

  16. Review of metastable states in heavy nuclei

    Science.gov (United States)

    Dracoulis, G. D.; Walker, P. M.; Kondev, F. G.

    2016-07-01

    The structure of nuclear isomeric states is reviewed in the context of their role in contemporary nuclear physics research. Emphasis is given to high-spin isomers in heavy nuclei, with A≳ 150 . The possibility to exploit isomers to study some of the most exotic nuclei is a recurring theme. In spherical nuclei, the role of octupole collectivity is discussed in detail, while in deformed nuclei the limitations of the K quantum number are addressed. Isomer targets and isomer beams are considered, along with applications related to energy storage, astrophysics, medicine, and experimental advances.

  17. Second sector cool down

    CERN Multimedia

    2007-01-01

    At the beginning of July, cool-down is starting in the second LHC sector, sector 4-5. The cool down of sector 4-5 may occasionally generate mist at Point 4, like that produced last January (photo) during the cool-down of sector 7-8.Things are getting colder in the LHC. Sector 7-8 has been kept at 1.9 K for three weeks with excellent stability (see Bulletin No. 16-17 of 16 April 2007). The electrical tests in this sector have got opt to a successful start. At the beginning of July the cryogenic teams started to cool a second sector, sector 4-5. At Point 4 in Echenevex, where one of the LHC’s cryogenic plants is located, preparations for the first phase of the cool-down are underway. During this phase, the sector will first be cooled to 80 K (-193°C), the temperature of liquid nitrogen. As for the first sector, 1200 tonnes of liquid nitrogen will be used for the cool-down. In fact, the nitrogen circulates only at the surface in the ...

  18. Measuring the coolness of interactive products: the COOL questionnaire

    DEFF Research Database (Denmark)

    Bruun, Anders; Raptis, Dimitrios; Kjeldskov, Jesper;

    2016-01-01

    is the COOL questionnaire. We based the creation of the questionnaire on literature suggesting that perceived coolness is decomposed to outer cool (the style of a product) and inner cool (the personality characteristics assigned to it). In this paper, we focused on inner cool, and we identified 11 inner cool......, rebelliousness and usability. These factors and their underlying 16 question items comprise the COOL questionnaire. The whole process of creating the questionnaire is presented in detail in this paper and we conclude by discussing our work against related work on coolness and HCI....

  19. Cavitation Nuclei: Experiments and Theory

    DEFF Research Database (Denmark)

    Mørch, Knud Aage

    2009-01-01

    The Swedish astrophysicist and Nobel Prize winner Hannes Alfven said: Theories come and go - the experiment is here forever. Often a theory, which we set up to describe an observed physical phenomenon, suffers from the lack of knowledge of decisive parameters, and therefore at best the theory...... becomes insufficient. Contrary, the experiment always reveals nature itself, though at prevailing experimental conditions. With essential parameters being out of control and even maybe unidentified, apparently similar experiments may deviate way beyond our expectations. However, these discrepancies offer...... us a chance to reflect on the character of the unknown parameters. In this way non-concordant experimental results may hold the key to the development of better theories - and to new experiments for the testing of their validity. Cavitation and cavitation nuclei are phenomena of that character....

  20. CAVITATION NUCLEI: EXPERIMENTS AND THEORY

    Institute of Scientific and Technical Information of China (English)

    MфRCH K. A.

    2009-01-01

    The Swedish astrophysicist and Nobel Prize winner Hannes Alfvén said: Theories come and go ─ the experiment is here forever. Often a theory, which we set up to describe an observed physical phenomenon, suffers from the lack of knowledge of decisive parameters, and therefore at best the theory becomes insufficient. Contrary, the experiment always reveals nature itself, though at prevailing experimental conditions. With essential parameters being out of control and even maybe unidentified, apparently similar experiments may deviate way beyond our expectations. However, these discrepancies offer us a chance to reflect on the character of the unknown parameters. In this way non-concordant experimental results may hold the key to the development of better theories – and to new experiments for the testing of their validity. Cavitation and cavitation nuclei are phenomena of that character.

  1. Inclusive breakup of Borromean nuclei

    CERN Document Server

    Hussein, Mahir S; Frederico, Tobias

    2016-01-01

    We derive the inclusive breakup cross section of a three-fragment projectile nuclei, $a = b +x_1 + x_2$, in the spectator model. The resulting four-body cross section for observing $b$, is composed of the elastic breakup cross section which contains information about the correlation between the two participant fragments, and the inclusive non-elastic breakup cross section. This latter cross section is found to be a non-trivial four-body generalization of the Austern formula \\cite{Austern1987}, which is proportional to a matrix element of the form, $\\langle\\hat{\\rho}_{{x_1},{x_2}}\\left|\\left[W_{{x_1}} + W_{{x_2}} + W_{3B}\\right]\\right|\\hat{\\rho}_{{x_1}, {x_2}}\\rangle$. The new feature here is the three-body absorption, represented by the imaginary potential, $W_{3B}$. We analyze this type of absorption and supply ideas of how to calculate its contribution.

  2. Formation of $\\phi$ mesic nuclei

    CERN Document Server

    Yamagata-Sekihara, J; Vacas, M J Vicente; Hirenzaki, S

    2010-01-01

    We study the structure and formation of the $\\phi$ mesic nuclei to investigate the in-medium modification of the $\\phi$-meson spectral function at finite density. We consider (${\\bar p},\\phi$), ($\\gamma,p$) and ($\\pi^-,n$) reactions to produce a $\\phi$-meson inside the nucleus and evaluate the effects of its medium modifications to the reaction cross sections. We also estimate the consequences of the uncertainties of the ${\\bar K}$ selfenergy in medium to the $\\phi$-nucleus interaction. We find that it may be possible to see a peak structure in the reaction spectra for the strong attractive potential cases. On the other hand, for strong absorptive interaction cases with relatively weak attractions, it is very difficult to observe clear peaks and we may need to know the spectrum shape in a wide energy region to deduce the properties of $\\phi$.

  3. Quasifree kaon photoproduction on nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Frank Lee; T. MART; Cornelius Bennhold; Lester Wright

    2001-12-01

    Investigations of the quasifree reaction A({gamma}, K Y)B are presented in the distorted wave impulse approximation (DWIA). For this purpose, we present a revised tree-level model of elementary kaon photoproduction that incorporates hadronic form factors consistent with gauge invariance, uses SU(3) values for the Born couplings and uses resonances consistent with multi-channel analyses. The potential of exclusive quasifree kaon photoproduction on nuclei to reveal details of the hyperon-nucleus interaction is examined. Detailed predictions for the coincidence cross section, the photon asymmetry, and the hyperon polarization and their sensitivities to the ingredients of the model are obtained for all six production channels. Under selected kinematics these observables are found to be sensitive to the hyperon-nucleus final state interaction. Some polarization observables are found to be insensitive to distortion effects, making them ideal tools to search for possible medium modifications of the elementary amplitude.

  4. Cool WISPs for stellar cooling excesses

    Energy Technology Data Exchange (ETDEWEB)

    Giannotti, Maurizio [Barry Univ., Miami Shores, FL (United States). Physical Sciences; Irastorza, Igor [Zaragoza Univ. (Spain). Dept. de Fisica Teorica; Redondo, Javier [Zaragoza Univ. (Spain). Dept. de Fisica Teorica; Max-Planck-Institut fuer Physik, Muenchen (Germany); Ringwald, Andreas [DESY Hamburg (Germany). Theory Group

    2015-12-15

    Several stellar systems (white dwarfs, red giants, horizontal branch stars and possibly the neutron star in the supernova remnant Cassiopeia A) show a preference for a mild non-standard cooling mechanism when compared with theoretical models. This exotic cooling could be provided by Weakly Interacting Slim Particles (WISPs), produced in the hot cores and abandoning the star unimpeded, contributing directly to the energy loss. Taken individually, these excesses do not show a strong statistical weight. However, if one mechanism could consistently explain several of them, the hint could be significant. We analyze the hints in terms of neutrino anomalous magnetic moments, minicharged particles, hidden photons and axion-like particles (ALPs). Among them, the ALP represents the best solution. Interestingly, the hinted ALP parameter space is accessible to the next generation proposed ALP searches, such as ALPS II and IAXO.

  5. Cool WISPs for stellar cooling excesses

    CERN Document Server

    Giannotti, Maurizio; Redondo, Javier; Ringwald, Andreas

    2015-01-01

    Several stellar systems (white dwarfs, red giants, horizontal branch stars and possibly the neutron star in the supernova remnant Cassiopeia A) show a preference for a mild non-standard cooling mechanism when compared with theoretical models. This exotic cooling could be provided by Weakly Interacting Slim Particles (WISPs), produced in the hot cores and abandoning the star unimpeded, contributing directly to the energy loss. Taken individually, these excesses do not show a strong statistical weight. However, if one mechanism could consistently explain several of them, the hint could be significant. We analyze the hints in terms of neutrino anomalous magnetic moments, minicharged particles, hidden photons and axion-like particles (ALPs). Among them, the ALP represents the best solution. Interestingly, the hinted ALP parameter space is accessible to the next generation proposed ALP searches, such as ALPS II and IAXO.

  6. Water-cooled electronics

    CERN Document Server

    Dumont, G; Righini, B

    2000-01-01

    LHC experiments demand on cooling of electronic instrumentation will be extremely high. A large number of racks will be located in underground caverns and counting rooms, where cooling by conventional climatisation would be prohibitively expensive. A series of tests on the direct water cooling of VMEbus units and of their standard power supplies is reported. A maximum dissipation of 60 W for each module and more than 1000 W delivered by the power supply to the crate have been reached. These values comply with the VMEbus specifications. (3 refs).

  7. Decay of heavy and superheavy nuclei

    Indian Academy of Sciences (India)

    K P Santhosh

    2014-04-01

    We present here, an overview and progress of the theoretical works on the isomeric state decay, decay fine structure of even–even, even–odd, odd–even and odd–odd nuclei, a study on the feasibility of observing decay chains from the isotopes of the superheavy nuclei = 115 in the range 271 ≤ ≤ 294 and the isotopes of = 117 in the range 270 ≤ ≤ 301, within the Coulomb and proximity potential model for deformed nuclei (CPPMDN). The computed half-lives of the favoured and unfavoured decay of nuclei in the range 67 ≤ ≤ 91 from both the ground state and isomeric state, are in good agreement with the experimental data and the standard deviation of half-life is found to be 0.44. From the fine structure studies done on various ranges of nuclei, it is evident that, for nearly all the transitions, the theoretical values show good match with the experimental values. This reveals that CPPMDN is successful in explaining the fine structure of even–even, even–odd, odd–even and odd–odd nuclei. Our studies on the decay of the superheavy nuclei 271−294115 and 270−301117 predict 4 chains consistently from 284,285,286115 nuclei and 5 chains and 3 chains consistently from 288−291117 and 292117, respectively. We thus hope that these studies on 284−286115 and 288−292117 will be a guide to future experiments.

  8. Isovector multiphonon excitations in near spherical nuclei

    CERN Document Server

    Smirnova, N A; Pietralla, N; Van Isacker, P; Isacker, Piet Van; Mizusaki, Takahiro; Pietralla, Norbert; Smirnova, Nadya A.

    2000-01-01

    The lowest isoscalar and isovector quadrupole and octupole excitations in near spherical nuclei are studied within the the proton-neutron version of the interacting boson model including quadrupole and octupole bosons (sdf-IBM-2). The main decay modes of these states in near spherical nuclei are discussed.

  9. Partial Dynamical Symmetry in Deformed Nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Leviatan, A. [Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel)

    1996-07-01

    We discuss the notion of partial dynamical symmetry in relation to nuclear spectroscopy. Explicit forms of Hamiltonians with partial SU(3) symmetry are presented in the framework of the interacting boson model of nuclei. An analysis of the resulting spectrum and electromagnetic transitions demonstrates the relevance of such partial symmetry to the spectroscopy of axially deformed nuclei. {copyright} {ital 1996 The American Physical Society.}

  10. Partial dynamical symmetry in deformed nuclei

    CERN Document Server

    Leviatan, A

    1996-01-01

    We discuss the notion of partial dynamical symmetry in relation to nuclear spectroscopy. Explicit forms of Hamiltonians with partial SU(3) symmetry are presented in the framework of the interacting boson model of nuclei. An analysis of the resulting spectrum and electromagnetic transitions demonstrates the relevance of such partial symmetry to the spectroscopy of axially deformed nuclei.

  11. Positron production in collision of heavy nuclei

    CERN Document Server

    Khriplovich, I B

    2016-01-01

    We consider the electromagnetic production of positron in collision of slow heavy nuclei, with the simultaneously produced electron captured by one of the nuclei. The cross-section of the discussed process exceeds essentially the cross-section of $e^+e^-$ production.

  12. RFP for the Comet Nuclei Tour (CONTOUR)

    DEFF Research Database (Denmark)

    Jørgensen, John Leif; Madsen, Peter Buch; Betto, Maurizio

    1999-01-01

    This document describes the ASC Star Tracker (performance, functionality, requirements etc.) to The Johns Hopkins University - Applied Physics Laboratory for their Comet Nuclei TOUR (CONTOUR) Program.......This document describes the ASC Star Tracker (performance, functionality, requirements etc.) to The Johns Hopkins University - Applied Physics Laboratory for their Comet Nuclei TOUR (CONTOUR) Program....

  13. Towards the exact calculation of medium nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Gandolfi, Stefano [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Carlson, Joseph Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lonardoni, Diego [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wang, Xiaobao [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-12-19

    The prediction of the structure of light and medium nuclei is crucial to test our knowledge of nuclear interactions. The calculation of the nuclei from two- and three-nucleon interactions obtained from rst principle is, however, one of the most challenging problems for many-body nuclear physics.

  14. Variation of hadron masses in finite nuclei

    CERN Document Server

    Saitô, K; Tsushima, K; Saito, Koichi; Thomas, Anthony W.; Tsushima, Kazuo

    1997-01-01

    Using a self-consistent, Hartree description for both infinite nuclear matter and finite nuclei based on a relativistic quark model (the quark-meson coupling model), we investigate the variation of the masses of the non-strange vector mesons, the hyperons and the nucleon in infinite nuclear matter and in finite nuclei.

  15. Energy Radiation of the Active Galactic Nuclei

    Institute of Scientific and Technical Information of China (English)

    TANG Zhi-Ming; WANG Yong-Jiu

    2004-01-01

    In the Hellings-Nordtvedt theory, we obtain some expressions of energy radiation and mass defect effect for a kind of the active galactic nuclei, which is meaningful to calculating the energy radiation in the procession of forming this kind of celestial bodies. This calculation can give some interpretation for energy source of the jet from the active galactic nuclei.

  16. Mean-field models and exotic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Bender, M.; Buervenich, T.; Maruhn, J.A.; Greiner, W. [Inst. fuer Theoretische Physik, Univ. Frankfurt (Germany); Rutz, K. [Inst. fuer Theoretische Physik, Univ. Frankfurt (Germany)]|[Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Reinhard, P.G. [Inst. fuer Theoretische Physik, Univ. Erlangen (Germany)

    1998-06-01

    We discuss two widely used nuclear mean-field models, the relativistic mean-field model and the (nonrelativistic) Skyrme-Hartree-Fock model, and their capability to describe exotic nuclei. Test cases are superheavy nuclei and neutron-rich Sn isotopes. New information in this regime helps to fix hitherto loosely determined aspects of the models. (orig.)

  17. Two-temperature coronae in active galactic nuclei

    CERN Document Server

    Matteo, T D; Fabian, A C

    1997-01-01

    We show that coronal magnetic dissipation in thin active sheets that sandwich standard thin accretion disks in active galactic nuclei may account for canonical electron temperatures of a few $\\times 10^9$K if protons acquire most of the dissipated energy. Coulomb collisions transfer energy from the ions to the electrons, which subsequently cool rapidly by inverse-Compton scattering. In equilibrium, the proton energy density likely exceeds that of the magnetic field and both well exceed the electron and photon energy densities. The Coulomb energy transfer from protons to electrons is slow enough to maintain a high proton temperature, but fast enough to explain observed rapid X-ray variabilities in Seyferts. The $\\sim 10^9$K electron temperature is insensitive to the proton temperature when the latter is $\\ge 10^{12}$K.

  18. Cooling Devices in Laser therapy.

    Science.gov (United States)

    Das, Anupam; Sarda, Aarti; De, Abhishek

    2016-01-01

    Cooling devices and methods are now integrated into most laser systems, with a view to protecting the epidermis, reducing pain and erythema and improving the efficacy of laser. On the basis of method employed, it can be divided into contact cooling and non-contact cooling. With respect to timing of irradiation of laser, the nomenclatures include pre-cooling, parallel cooling and post-cooling. The choice of the cooling device is dictated by the laser device, the physician's personal choice with respect to user-friendliness, comfort of the patient, the price and maintenance costs of the device. We hereby briefly review the various techniques of cooling, employed in laser practice.

  19. LHC cooling gains ground

    CERN Multimedia

    Huillet-Miraton Catherine

    The nominal cryogenic conditions of 1.9 K have been achieved in sectors 5-6 and 7-8. This means that a quarter of the machine has reached the nominal conditions for LHC operation, having attained a temperature of below 2 K (-271°C), which is colder than interstellar space! Elsewhere, the cryogenic system in Sector 8-1 has been filled with liquid helium and cooled to 2K and will soon be available for magnet testing. Sectors 6-7 and 2-3 are being cooled down and cool-down operations have started in Sector 3-4. Finally, preparations are in hand for the cool-down of Sector 1-2 in May and of Sector 4-5, which is currently being consolidated. The LHC should be completely cold for the summer. For more information: http://lhc.web.cern.ch/lhc/Cooldown_status.htm.

  20. Why Exercise Is Cool

    Science.gov (United States)

    ... to Know About Puberty Train Your Temper Why Exercise Is Cool KidsHealth > For Kids > Why Exercise Is ... day and your body will thank you later! Exercise Makes Your Heart Happy You may know that ...

  1. Waveguide cooling system

    Science.gov (United States)

    Chen, B. C. J.; Hartop, R. W.

    1981-04-01

    An improved system is described for cooling high power waveguides by the use of cooling ducts extending along the waveguide, which minimizes hot spots at the flanges where waveguide sections are connected together. The cooling duct extends along substantially the full length of the waveguide section, and each flange at the end of the section has a through hole with an inner end connected to the duct and an opposite end that can be aligned with a flange hole in another waveguide section. Earth flange is formed with a drainage groove in its face, between the through hole and the waveguide conduit to prevent leakage of cooling fluid into the waveguide. The ducts have narrowed sections immediately adjacent to the flanges to provide room for the installation of fasteners closely around the waveguide channel.

  2. Warm and Cool Dinosaurs.

    Science.gov (United States)

    Mannlein, Sally

    2001-01-01

    Presents an art activity in which first grade students draw dinosaurs in order to learn about the concept of warm and cool colors. Explains how the activity also helped the students learn about the concept of distance when drawing. (CMK)

  3. Cooling of wood briquettes

    Directory of Open Access Journals (Sweden)

    Adžić Miroljub M.

    2013-01-01

    Full Text Available This paper is concerned with the experimental research of surface temperature of wood briquettes during cooling phase along the cooling line. The cooling phase is an important part of the briquette production technology. It should be performed with care, otherwise the quality of briquettes could deteriorate and possible changes of combustion characteristics of briquettes could happen. The briquette surface temperature was measured with an IR camera and a surface temperature probe at 42 sections. It was found that the temperature of briquette surface dropped from 68 to 34°C after 7 minutes spent at the cooling line. The temperature at the center of briquette, during the 6 hour storage, decreased to 38°C.

  4. Stacking with stochastic cooling

    Energy Technology Data Exchange (ETDEWEB)

    Caspers, Fritz E-mail: Fritz.Caspers@cern.ch; Moehl, Dieter

    2004-10-11

    Accumulation of large stacks of antiprotons or ions with the aid of stochastic cooling is more delicate than cooling a constant intensity beam. Basically the difficulty stems from the fact that the optimized gain and the cooling rate are inversely proportional to the number of particles 'seen' by the cooling system. Therefore, to maintain fast stacking, the newly injected batch has to be strongly 'protected' from the Schottky noise of the stack. Vice versa the stack has to be efficiently 'shielded' against the high gain cooling system for the injected beam. In the antiproton accumulators with stacking ratios up to 10{sup 5} the problem is solved by radial separation of the injection and the stack orbits in a region of large dispersion. An array of several tapered cooling systems with a matched gain profile provides a continuous particle flux towards the high-density stack core. Shielding of the different systems from each other is obtained both through the spatial separation and via the revolution frequencies (filters). In the 'old AA', where the antiproton collection and stacking was done in one single ring, the injected beam was further shielded during cooling by means of a movable shutter. The complexity of these systems is very high. For more modest stacking ratios, one might use azimuthal rather than radial separation of stack and injected beam. Schematically half of the circumference would be used to accept and cool new beam and the remainder to house the stack. Fast gating is then required between the high gain cooling of the injected beam and the low gain stack cooling. RF-gymnastics are used to merge the pre-cooled batch with the stack, to re-create free space for the next injection, and to capture the new batch. This scheme is less demanding for the storage ring lattice, but at the expense of some reduction in stacking rate. The talk reviews the 'radial' separation schemes and also gives some

  5. Cooling of electronic equipment

    DEFF Research Database (Denmark)

    A. Kristensen, Anders Schmidt

    2003-01-01

    Cooling of electronic equipment is studied. The design size of electronic equipment decrease causing the thermal density to increase. This affect the cooling which can cause for example failures of critical components due to overheating or thermal induced stresses. Initially a pin fin heat sink...... is considered as extruded profiles are inadequate for compact designs. An optimal pin fin shape and configuration is sought also taking manufacturing costs into consideration. Standard methods for geometrical modeling and thermal analysis are applied....

  6. Anomalous law of cooling

    OpenAIRE

    Lapas, Luciano C.; Ferreira, Rogelma M. S.; Oliveira, Fernando A.; Rubí, J. Miguel

    2014-01-01

    We analyze the temperature relaxation phenomena of systems in contact with a thermal reservoir that undergo a non-Markovian diffusion process. From a generalized Langevin equation, we show that the temperature is governed by a law of cooling of the Newton's law type in which the relaxation time depends on the velocity autocorrelation and is then characterized by the memory function. The analysis of the temperature decay reveals the existence of an anomalous cooling in which the temperature ma...

  7. Cooling tower waste reduction

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, S.J.; Celeste, J.; Chine, R.; Scott, C.

    1998-05-01

    At Lawrence Livermore National Laboratory (LLNL), the two main cooling tower systems (central and northwest) were upgraded during the summer of 1997 to reduce the generation of hazardous waste. In 1996, these two tower systems generated approximately 135,400 lbs (61,400 kg) of hazardous sludge, which is more than 90 percent of the hazardous waste for the site annually. At both, wet decks (cascade reservoirs) were covered to block sunlight. Covering the cascade reservoirs reduced the amount of chemical conditioners (e.g. algaecide and biocide), required and in turn the amount of waste generated was reduced. Additionally, at the northwest cooling tower system, a sand filtration system was installed to allow cyclical filtering and backflushing, and new pumps, piping, and spray nozzles were installed to increase agitation. the appurtenance upgrade increased the efficiency of the cooling towers. The sand filtration system at the northwest cooling tower system enables operators to continuously maintain the cooling tower water quality without taking the towers out of service. Operational costs (including waste handling and disposal) and maintenance activities are compared for the cooling towers before and after upgrades. Additionally, the effectiveness of the sand filter system in conjunction with the wet deck covers (northwest cooling tower system), versus the cascade reservoir covers alone (south cooling tower south) is discussed. the overall expected return on investment is calculated to be in excess of 250 percent. this upgrade has been incorporated into the 1998 DOE complex-wide water conservation project being led by Sandia National Laboratory/Albuquerque.

  8. Cooling with Superfluid Helium

    CERN Document Server

    Lebrun, P

    2014-01-01

    The technical properties of helium II (‘superfluid’ helium) are presented in view of its applications to the cooling of superconducting devices, particularly in particle accelerators. Cooling schemes are discussed in terms of heat transfer performance and limitations. Large-capacity refrigeration techniques below 2 K are reviewed, with regard to thermodynamic cycles as well as process machinery. Examples drawn from existing or planned projects illustrate the presentation. Keywords: superfluid helium, cryogenics

  9. Laser cooling of solids

    Energy Technology Data Exchange (ETDEWEB)

    Epstein, Richard I [Los Alamos National Laboratory; Sheik-bahae, Mansoor [UNM

    2008-01-01

    We present an overview of solid-state optical refrigeration also known as laser cooling in solids by fluorescence upconversion. The idea of cooling a solid-state optical material by simply shining a laser beam onto it may sound counter intuitive but is rapidly becoming a promising technology for future cryocooler. We chart the evolution of this science in rare-earth doped solids and semiconductors.

  10. Total Nuclear Reaction Cross Section Induced by Halo Nuclei and Stable Nuclei

    Institute of Scientific and Technical Information of China (English)

    GUO Wen-Jun; JIANG Huan-Qing; LIU Jian-Ye; ZUO Wei; REN Zhong-Zhou; LEE Xi-Guo

    2003-01-01

    We develop a method for calculation of the total reaction cross sections induced by the halo nuclei and stable. nuclei. This approach is based on the Glauber theory, which is valid for nuclear reactions at high energies. It is extended for nuclear reactions at low energies and intermediate energies by including both the quantum correction and Coulomb correction under the assumption of the effective nuclear density distribution. The calculated results of the total reaction cross section induced by stable nuclei agree well with 30 experimental data within 10 percent accuracy. The comparison between the numerical results and 20 experimental data for the total nuclear reaction cross section induced by the neutron halo nuclei and the proton halo nuclei indicates a satisfactory agreement after considering the halo structure of these nuclei, which implies quite different mean fields for the nuclear reactions induced by halo nuclei and stable nuclei. The halo nucleon distributions and the root-mean-square radii of these nuclei can be extracted from the above comparison based on the improved Glauber model, which indicates clearly the halo structures of these nuclei. Especially,it is clear to see that the medium correction of the nucleon-nucleon collision has little effect on the total reaction cross sections induced by the halo nuclei due to the very weak binding and the very extended density distribution.

  11. Total Nuclear Reaction Cross Section Induced by Halo Nuclei and Stable Nuclei

    Institute of Scientific and Technical Information of China (English)

    GUOWen-Jun; JIANGHuan-Qing; LIUJian-Ye; ZUOWei; RENZhong-Zhou; LEEXi-Guo

    2003-01-01

    We develop a method for calculation of the total reaction cross sections induced by the halo nuclei and stable nuclei. This approach is based on the Glauber theory, which is valid for nuclear reactions at high energies. It is extended for nuclear reactions at low energies and intermediate energies by including both the quantum correction and Coulomb correction under the assumption of the effective nuclear density distribution. The calculated results of the total reaction cross section induced by stable nuclei agree well with 30 experimental data within 10 percent accuracy.The comparison between the numerical results and 20 experimental data for the total nuclear reaction cross section induced by the neutron halo nuclei and the proton halo nuclei indicates a satisfactory agreement after considering the halo structure of these nuclei, which implies quite digerent mean fields for the nuclear reactions induced by halo nuclei and stable nuclei. The halo nucleon distributions and the root-mean-square radii of these nuclei can be extracted from the above comparison based on the improved Glauber model, which indicates clearly the halo structures of these nuclei. Especially,it is clear to see that the medium correction of the nucleon-nucleon collision has little effect on the total reaction cross sections, induced by the halo nuclei due to the very weak binding and the very extended density distribution.

  12. Stacking with Stochastic Cooling

    CERN Document Server

    Caspers, Friedhelm

    2004-01-01

    Accumulation of large stacks of antiprotons or ions with the aid of stochastic cooling is more delicate than cooling a constant intensity beam. Basically the difficulty stems from the fact that the optimized gain and the cooling rate are inversely proportional to the number of particles seen by the cooling system. Therefore, to maintain fast stacking, the newly injected batch has to be strongly protected from the Schottky noise of the stack. Vice versa the stack has to be efficiently shielded against the high gain cooling system for the injected beam. In the antiproton accumulators with stacking ratios up to 105, the problem is solved by radial separation of the injection and the stack orbits in a region of large dispersion. An array of several tapered cooling systems with a matched gain profile provides a continuous particle flux towards the high-density stack core. Shielding of the different systems from each other is obtained both through the spatial separation and via the revolution frequencies (filters)....

  13. Alternative Room Cooling System

    Directory of Open Access Journals (Sweden)

    Md. Fazle Rabbi

    2015-06-01

    Full Text Available The rapidly growing population results in an increasing demand for much more residential and commercial buildings, which leads to vertical growth of the buildings and needs proper ventilation of those buildings. Natural air ventilation system is not sufficient for conventional building structures. Hence fans and air-conditioners are must to meet the requirement of proper ventilation as well as space conditioning. Globally building sector consumes largest energy in heating, cooling, ventilation and space conditioning. This load can be minimized by the application of solar chimney and modification in building structure for heating, cooling, ventilation and space conditioning. Passive solar cooling is a subject of interest to provide cooling by using the sun, a powerful energy source. This is done for ensuring human comfort in hot climates. ASHRAE (American Society of Heating, Refrigerating and Air Conditioning Engineers defines Comfort as ‘that state of mind which expresses satisfaction with the thermal environment.’ The present paper describes the development of a solar passive cooling system, which can provide thermal cooling throughout the summer season in hot and humid climates. The constructed passive system works on natural convection mode of air. Such system reduces the inside temperature of up to 5°C from the atmospheric temperature. Temperature can further be reduced by the judicious use of night ventilation.

  14. Comparing Social Stories™ to Cool versus Not Cool

    Science.gov (United States)

    Leaf, Justin B.; Mitchell, Erin; Townley-Cochran, Donna; McEachin, John; Taubman, Mitchell; Leaf, Ronald

    2016-01-01

    In this study we compared the cool versus not cool procedure to Social Stories™ for teaching various social behaviors to one individual diagnosed with autism spectrum disorder. The researchers randomly assigned three social skills to the cool versus not cool procedure and three social skills to the Social Stories™ procedure. Naturalistic probes…

  15. Fusion probability in heavy nuclei

    Science.gov (United States)

    Banerjee, Tathagata; Nath, S.; Pal, Santanu

    2015-03-01

    Background: Fusion between two massive nuclei is a very complex process and is characterized by three stages: (a) capture inside the potential barrier, (b) formation of an equilibrated compound nucleus (CN), and (c) statistical decay of the CN leading to a cold evaporation residue (ER) or fission. The second stage is the least understood of the three and is the most crucial in predicting yield of superheavy elements (SHE) formed in complete fusion reactions. Purpose: A systematic study of average fusion probability, PCN> , is undertaken to obtain a better understanding of its dependence on various reaction parameters. The study may also help to clearly demarcate onset of non-CN fission (NCNF), which causes fusion probability, PCN, to deviate from unity. Method: ER excitation functions for 52 reactions leading to CN in the mass region 170-220, which are available in the literature, have been compared with statistical model (SM) calculations. Capture cross sections have been obtained from a coupled-channels code. In the SM, shell corrections in both the level density and the fission barrier have been included. PCN> for these reactions has been extracted by comparing experimental and theoretical ER excitation functions in the energy range ˜5 %-35% above the potential barrier, where known effects of nuclear structure are insignificant. Results: PCN> has been shown to vary with entrance channel mass asymmetry, η (or charge product, ZpZt ), as well as with fissility of the CN, χCN. No parameter has been found to be adequate as a single scaling variable to determine PCN> . Approximate boundaries have been obtained from where PCN> starts deviating from unity. Conclusions: This study quite clearly reveals the limits of applicability of the SM in interpreting experimental observables from fusion reactions involving two massive nuclei. Deviation of PCN> from unity marks the beginning of the domain of dynamical models of fusion. Availability of precise ER cross sections

  16. Measuring the coolness of interactive products: the COOL questionnaire

    DEFF Research Database (Denmark)

    Bruun, Anders; Raptis, Dimitrios; Kjeldskov, Jesper

    2016-01-01

    characteristics. These were used to create an initial pool of question items and 2236 participants were asked to assess 16 mobile devices. By performing exploratory and confirmatory factor analyses, we identified three factors that can measure the perceived inner coolness of interactive products: desirability...... is the COOL questionnaire. We based the creation of the questionnaire on literature suggesting that perceived coolness is decomposed to outer cool (the style of a product) and inner cool (the personality characteristics assigned to it). In this paper, we focused on inner cool, and we identified 11 inner cool...

  17. Chemical complexity in galactic nuclei

    Science.gov (United States)

    Martin-Pintado, Jesus

    2007-12-01

    In recent years our knowledge of the chemical complexity in the nuclei of galaxies has dramatically changed. Recent observations of the nucleus of the Milky Way, of the starburst galaxy NGC253 and of the ultraluminous infrared galaxy (ULIRG) Arp220 have shown large abundance of complex organic molecules believed to be formed on grains. The Galactic center appears to be the largest repository of complex organic molecule like aldehydes and alcohols in the galaxy. We also measure large abundance of methanol in starburst galaxies and in ULIRGs suggesting that complex organic molecules are also efficiently produced in the central region of galaxies with strong star formation activity. From the systematic observational studies of molecular abundance in regions dominated by different heating processes like shocks, UV radiation, X-rays and cosmic rays in the center of the Milky Way, we are opening the possibility of using chemistry as a diagnostic tool to study the highly obscured regions of galactic centers. The templates found in the nucleus of the Milky Way will be used to establish the main mechanisms driving the heating and the chemistry of the molecular clouds in galaxies with different type of activity. The role of grain chemistry in the chemical complexity observed in the center of galaxies will be also briefly discussed.

  18. The morphology of cometary nuclei

    Science.gov (United States)

    Keller, H. U.; Jorda, L.

    comets display residual activity or clouds of dust grains around their nuclei. Taking the residual signal into account (mostly using simple models for the brightness distribution) the size estimates of the nuclei could be improved. The (nuclear) magnitude of a comet depends on the product of its albedo and cross-section. Only in a few cases could the albedo and size of a cometary nucleus be separated by additional observation of its thermal emission at infrared wavelengths. By comparison with outer Solar System asteroids Cruikshank et al. (1985) derived a surprisingly low albedo of about 0.04. A value in clear contradiction to the perception of an icy surface but fully confirmed by the first resolved images of a cometary nucleus during the flybys of the Vega and Giotto spacecraft of comet Halley (Sagdeev et al. 1986, Keller et al. 1986). The improvements of radar techniques led to the detection of reflected signals and finally to the derivation of nuclear dimensions and rotation rates. The observations, however, are also model dependent (rotation and size are similarly interwoven as are albedo and size) and sensitive to large dust grains in the vicinity of a nucleus. As an example, Kamoun et al. (1982) determined the radius of comet Encke to 1.5 (2.3, 1.0) km using the spin axis determination of Whipple and Sekanina (1979). The superb spatial resolution of the Hubble Space Telescope (HST) is not quite sufficient to resolve a cometary nucleus. The intensity distribution of the inner coma, however, can be observed and extrapolated toward the nucleus based on models of the dust distribution. If this contribution is subtracted from the central brightness the signal of the nucleus can be derived and hence its product of albedo times cross-section (Lamy and Toth 1995, Rembor 1998, Keller and Rembor 1998; Section 4.3). It has become clear that cometary nuclei are dark, small, often irregular bodies with dimensions ranging from about a kilometre (comet Wirtanen, the target of

  19. Alpha decay chains from superheavy nuclei

    CERN Document Server

    Samanta, C

    2008-01-01

    Magic islands for extra-stable nuclei in the midst of the sea of fission-instability were predicted to be around Z=114, 124 or, 126 with N=184, and Z=120, with N=172. Whether these fission-survived superheavy nuclei with high Z and N would live long enough for detection or, undergo alpha-decay in a very short time remains an open question. Alpha-decay half lives of nuclei with 130 118 are found to have alpha-decay half lives of the order of microseconds or, less.

  20. Deep inelastic scattering on asymmetric nuclei

    Science.gov (United States)

    Saito, K.; Boros, C.; Tsushima, K.; Bissey, F.; Afnan, I. R.; Thomas, A. W.

    2000-11-01

    We study deep inelastic scattering on isospin asymmetric nuclei. In particular, the difference of the nuclear structure functions and the Gottfried sum rule for the lightest mirror nuclei, 3He and 3H, are investigated. It is found that such systems can provide significant information on charge symmetry breaking and flavor asymmetry in the nuclear medium. Furthermore, we propose a new method to extract the neutron structure function from radioactive isotopes far from the line of stability. We also discuss the flavor asymmetry in the Drell-Yan process with isospin asymmetric nuclei.

  1. Coupled-cluster computations of atomic nuclei

    CERN Document Server

    Hagen, G; Hjorth-Jensen, M; Dean, D J

    2013-01-01

    In the past decade, coupled-cluster theory has seen a renaissance in nuclear physics, with computations of neutron-rich and medium-mass nuclei. The method is efficient for nuclei with product-state references, and it describes many aspects of weakly bound and unbound nuclei. This report reviews the technical and conceptual developments of this method in nuclear physics, and the results of coupled-cluster calculations for nucleonic matter, and for exotic isotopes of helium, oxygen, calcium, and some of their neighbors.

  2. Direct mass measurements of {sup 100}Sn and magic nuclei near the N=Z line; Mesures directes des masses de {sup 100}Sn et de noyaux exotiques proches de la ligne N = Z

    Energy Technology Data Exchange (ETDEWEB)

    Chartier, M.

    1996-10-31

    The masses of nuclei far from stability are of particular interest in nuclear structure studies, and many methods of varying precision have been developed to undertake their measurement. A direct time of flight technique in conjunction with the SPEG spectrometer at GANIL has been extended to the mass measurement of proton-rich nuclei near N = Z line in the mass region A {approx_equal} 60-80 known to provide input for astrophysical modelling of the rp-process and information relevant to the nuclear structure in a region of high deformation. The radioactive beams were produced via the fragmentation of a {sup 78}Kr beam on a {sup nat}Ni target, using the new SISSI device. A purification method based on the stripping of the secondary ions was successfully used for the first time, and the masses of {sup 70}Se and {sup 71}Se were measured. In order to improve the mass resolution for heavier nuclei, another method using the second cyclotron of GANIL (CSS2) as a high resolution spectrometer has been developed. An experiment aimed at measuring the masses of A 100 isobars in the vicinity of the doubly magic nucleus {sup 100}Sn was successfully performed, using this original technique. Secondary ions of {sup 100}Ag, {sup 100}Cd, {sup 100}In and {sup 100}Sn produced via fusion-evaporation reaction {sup 50}Cr + {sup 58}Ni and simultaneously accelerated in the CSS2 cyclotron. The mass of {sup 100}Cd and, for the first time, the masses of {sup 100}Sn were determined directly with respect to the reference mass of {sup 100}Ag. These results have been compared to various theoretical predictions and open the discussion on considerations of spin-isospin symmetry. (author). 96 refs.

  3. The definition of cool

    Energy Technology Data Exchange (ETDEWEB)

    Nichiporuk, A.

    2005-05-01

    A new air cooling system at Agnico-Eagle's LaRonde mine, located in the Abitibi Region of Quebec is described. The new system serves a mine operating at 7,250 plus feet level. The system is installed at the surface; it utilizes ammonia to cool water, which cools the air. The system consists of four compressors which lower the temperature of the ammonia to minus 2 degrees C. Water, which at this temperature is 14 degrees, and ammonia pass through a plate heat exchanger simultaneously, however, without coming into contact with each other. The heat transfer that occurs causes the water's temperature to drop to 2 degrees C. The total volume of water cooled is 220 litres per second. The system is capable of reducing 636,000 cfm of air from 30 degrees C to 6 degrees C, to which 214,000 cfm of non-cooled air is added. This mixture, which is maintained at approximately 8 degrees C throughout the summer season, is sent underground to the deepest parts of the mine. The system runs from June to September, depending on the weather. In the evenings, when the temperature dips to around four to five degrees C, the water is shut down and side doors are opened to prevent the water from freezing.

  4. On the efficient acceleration of clouds in active galactic nuclei

    Science.gov (United States)

    Waters, Tim; Proga, Daniel

    2016-07-01

    In the broad line region of active galactic nuclei (AGN), acceleration occurs naturally when a cloud condenses out of the hot confining medium due to the increase in line opacity as the cloud cools. However, acceleration by radiation pressure is not very efficient when the flux is time-independent, unless the flow is 1D. Here, we explore how acceleration is affected by a time-varying flux, as AGN are known to be highly variable. If the period of flux oscillations is longer than the thermal time-scale, we expect the gas to cool during the low flux state, and therefore line opacity should quickly increase. The cloud will receive a small kick due to the increased radiation force. We perform hydrodynamical simulations using ATHENA to confirm this effect and quantify its importance. We find that despite the flow becoming turbulent in 2D due to hydrodynamic instabilities, a 20 per cent modulation of the flux leads to a net increase in acceleration - by more than a factor of 2 - in both 1D and 2D. We show that this acceleration is sufficient to produce the observed line widths, although we only consider optically thin clouds. We discuss the implications of our results for photoionization modelling and reverberation mapping.

  5. Feedback from Active Galactic Nuclei: Energy- versus momentum-driving

    CERN Document Server

    Costa, Tiago; Haehnelt, Martin G

    2014-01-01

    We employ hydrodynamical simulations using the moving-mesh code AREPO to investigate the role of energy and momentum input from Active Galactic Nuclei (AGN) in driving large-scale galactic outflows. We start by reproducing analytic solutions for both energy- and momentum-driven outflowing shells in simulations of a spherical isolated dark matter potential with gas in hydrostatic equilibrium and with no radiative cooling. We confirm that for this simplified setup, galactic outflows driven by a momentum input rate of order L_Edd/c can establish an M_BH - sigma relation with slope and normalisation similar to that observed. We show that momentum input at a rate of L_Edd/c is however insufficient to drive efficient outflows once cooling and gas inflows as predicted by cosmological simulations at resolved scales are taken into account. We argue that observed large-scale AGN-driven outflows are instead likely to be energy-driven and show that such outflows can reach momentum fluxes exceeding 10 L_Edd/c within the i...

  6. Aspects of Household Cooling Technology

    OpenAIRE

    Mrzyglod, Matthias; Holzer, Stefan

    2014-01-01

    Actually available household cooling appliances in the highest efficiency class may consume less then 10W average electrical power. To achieve such power consumptions special challenges for the cooling system had to overcome. The related cooling system design has to consider several effects, which arise from the corresponding low cooling capacity demand, start/stop cycles and additional power consumptions by control accessories. The lecture provides symptomatic aspects of cooling technology, ...

  7. Doppler cooling a microsphere

    CERN Document Server

    Barker, P F

    2010-01-01

    Doppler cooling the center-of-mass motion of an optically levitated microsphere via the velocity dependent scattering force from narrow whispering gallery mode (WGM) resonances is described. Light that is red detuned from the WGM resonance can be used to damp the center-of-mass motion in a process analogous to the Doppler cooling of atoms. Leakage of photons out of the microsphere when the incident field is near resonant with the narrow WGM resonance acts to damp the motion of the sphere. The scattering force is not limited by saturation, but can be controlled by the incident power. Cooling times on the order of seconds are calculated for a 20 micron diameter silica microsphere trapped within optical tweezers, with a Doppler temperature limit in the microKelvin regime.

  8. Natural radiative cooling

    Energy Technology Data Exchange (ETDEWEB)

    Lazzarin, R.

    1979-01-01

    Natural radiative cooling at night was measured based on the surface-radiation spectrum after the heat balance of the surface exposed to the sun had been reradiated. A concept equivalent to the sky temperature and a concept useful for obtaining the net heat flux are discussed. The highest possible equilibrium temperature of the selective surface can be lowered; however, how to apply this practically is not yet known. A simple radiator, completely enclosed by a transparent screen, can produce a significant and inexpensive cooling effect. The results of experiments carried out in an area such as Padua, Italy, where the climate is not suitable for cooling purposes can still be predicted theoretically. The possibility of using the collector for heat collection during the day and as a radiator at night is indicated.

  9. Clean cooling; Saubere Kuehlung

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1998-07-01

    The round hybrid cooling towers which Balcke-Duerr GmbH is currently building for the 550-MW-IGCC-power-station of a refinery project on Sardinia have to meet particularly stringent requirements as seawater is used for cooling. The advantages are: Avoidance of visible plume with minimal energy consumption, optimal plume exit velocity and discharge, greatest possible stability of the plume column, avoidance of interference and recirculation, high operating reliability of the cooling tower. (orig.) [Deutsch] Derzeit werden die Kuehltuerme fuer ein 550-MW-IGCC-Kraftwerk einer Raffinierie auf Sardinien errichtet. Die Anforderungen an die Technik sind hoch, denn gekuehlt wird mit Seewasser. Zum Einsatz kommen Hybridrundkuehltuerme der Balcke-Duerr GmbH, Ratingen. Damit setzt das Unternehmen diesen Typ erstmals ausserhalb von Deutschland ein. (orig.)

  10. Monitoring Cray Cooling Systems

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, Don E [ORNL; Ezell, Matthew A [ORNL; Becklehimer, Jeff [Cray, Inc.; Donovan, Matthew J [ORNL; Layton, Christopher C [ORNL

    2014-01-01

    While sites generally have systems in place to monitor the health of Cray computers themselves, often the cooling systems are ignored until a computer failure requires investigation into the source of the failure. The Liebert XDP units used to cool the Cray XE/XK models as well as the Cray proprietary cooling system used for the Cray XC30 models provide data useful for health monitoring. Unfortunately, this valuable information is often available only to custom solutions not accessible by a center-wide monitoring system or is simply ignored entirely. In this paper, methods and tools used to harvest the monitoring data available are discussed, and the implementation needed to integrate the data into a center-wide monitoring system at the Oak Ridge National Laboratory is provided.

  11. Research on Cooling Effectiveness in Stepped Slot Film Cooling Vane

    Institute of Scientific and Technical Information of China (English)

    LI Yulong; WU Hong; ZHOU Feng; RONG Chengjun

    2016-01-01

    As one of the most important developments in air cooling technology for hot parts of the aero-engine,film cooling technology has been widely used.Film cooling hole structure exists mainly in areas that have high temperature,uneven cooling effectiveness issues when in actual use.The first stage turbine vanes of the aero-engine consume the largest portion of cooling air,thereby the research on reducing the amount of cooling air has the greatest potential.A new stepped slot film cooling vane with a high cooling effectiveness and a high cooling uniformity was researched initially.Through numerical methods,the affecting factors of the cooling effectiveness of a vane with the stepped slot film cooling structure were researched.This paper focuses on the cooling effectiveness and the pressure loss in different blowing ratio conditions,then the most reasonable and scientific structure parameter can be obtained by analyzing the results.The results show that 1.0 mm is the optimum slot width and 10.0 is the most reasonable blowing ratio.Under this condition,the vane achieved the best cooling result and the highest cooling effectiveness,and also retained a low pressure loss.

  12. Critical-Point Structure in Finite Nuclei

    CERN Document Server

    Leviatan, A

    2006-01-01

    Properties of quantum shape-phase transitions in finite nuclei are considered in the framework of the interacting boson model. Special emphasis is paid to the dynamics at the critical-point of a general first-order phase transition.

  13. Few-Body Universality in Halo Nuclei

    Directory of Open Access Journals (Sweden)

    Hammer H.-W.

    2016-01-01

    Full Text Available Few-body systems with resonant S-wave interactions show universal properties which are independent of the interaction at short distances. These properties include a geometric spectrum of three- and higher-body bound states and universal correlations between few-body observables. They can be observed on a wide range of scales from hadrons and nuclei to ultracold atoms. In this contribution, we focus on few-body universality in halo nuclei which can be considered as effective few-body systems consisting of halo nucleons and a core. This concept provides a unifying framework for halo nuclei with calculable corrections. Recent progress in this field with an emphasis on the possibility of finding Efimov states in halo nuclei is discussed.

  14. Few-Body Universality in Halo Nuclei

    Science.gov (United States)

    Hammer, H.-W.

    2016-03-01

    Few-body systems with resonant S-wave interactions show universal properties which are independent of the interaction at short distances. These properties include a geometric spectrum of three- and higher-body bound states and universal correlations between few-body observables. They can be observed on a wide range of scales from hadrons and nuclei to ultracold atoms. In this contribution, we focus on few-body universality in halo nuclei which can be considered as effective few-body systems consisting of halo nucleons and a core. This concept provides a unifying framework for halo nuclei with calculable corrections. Recent progress in this field with an emphasis on the possibility of finding Efimov states in halo nuclei is discussed.

  15. GDR in Hot Nuclei: New Measurements

    Science.gov (United States)

    Camera, F.; Kmiecik, M.; Wieland, O.; Benzoni, G.; Bracco, A.; Brambilla, S.; Crespi, F.; Mason, P.; Moroni, A.; Million, B.; Leoni, S.; Maj, A.; Styczen, J.; Brekiesz, M.; Meczynski, W.; Zieblinski, M.; Gramegna, F.; Barlini, S.; Kravchuk, V. L.; Lanchais, A. L.; Mastinu, P. F.; Bruno, M.; D'Agostino, M.; Geraci, E.; Ordine, A.; Casini, G.; Chiari, M.

    2005-04-01

    The measured properties of the Giant Dipole Resonance in hot rotating nuclei are successfully described with the model of thermal fluctuations, even though there are still some open problems especially at very low (T 2.5MeV) temperatures and missing data in some mass regions. Recent experimental works have addressed more specific problems regarding the nuclear shape and its behaviour in very particular and delimited phase space regions. In this paper will be discussed new exclusive measurements of the GDR γ decay in heavy 216Rn nuclei (where the shape of nuclei surviving fission have been probed) and some preliminary data on the 132Ce nuclei at very high excitation energy.

  16. Quantum Monte Carlo Calculations of Light Nuclei

    CERN Document Server

    Pieper, Steven C

    2007-01-01

    During the last 15 years, there has been much progress in defining the nuclear Hamiltonian and applying quantum Monte Carlo methods to the calculation of light nuclei. I describe both aspects of this work and some recent results.

  17. On The Structure of A=3 Nuclei

    CERN Document Server

    Abbas, Syed Afsar

    2011-01-01

    The hole in the charge distribution of $^3{\\text He}$ is a major problem in A=3 nuclei. The canonical wavefucntion of A=3 nuclei which does well for electromagnetic properties of A=3 nuclei fails to produce the hole in A=3 nuclei. The hole is normally assumed to arise from explicit quark degree of freedom. Very often quark degrees of freedom are imposed to propose a different short range part of the wavefunction for A=3 to explain the hole in $^3{\\text He}$. So an hybrid model with nucleonic degree of freedom in outer part and quark degrees of freedom in the inner part of the nucleus have been invoked to understand the above problem. Here we present a different picture with a new wavefunction working at short range within nucleonic degrees of freedom itself. So the above problem is explained here based entirely on the nucleonic degree of freedom only.

  18. Anomalous law of cooling.

    Science.gov (United States)

    Lapas, Luciano C; Ferreira, Rogelma M S; Rubí, J Miguel; Oliveira, Fernando A

    2015-03-14

    We analyze the temperature relaxation phenomena of systems in contact with a thermal reservoir that undergoes a non-Markovian diffusion process. From a generalized Langevin equation, we show that the temperature is governed by a law of cooling of the Newton's law type in which the relaxation time depends on the velocity autocorrelation and is then characterized by the memory function. The analysis of the temperature decay reveals the existence of an anomalous cooling in which the temperature may oscillate. Despite this anomalous behavior, we show that the variation of entropy remains always positive in accordance with the second law of thermodynamics.

  19. Anomalous law of cooling

    Science.gov (United States)

    Lapas, Luciano C.; Ferreira, Rogelma M. S.; Rubí, J. Miguel; Oliveira, Fernando A.

    2015-03-01

    We analyze the temperature relaxation phenomena of systems in contact with a thermal reservoir that undergoes a non-Markovian diffusion process. From a generalized Langevin equation, we show that the temperature is governed by a law of cooling of the Newton's law type in which the relaxation time depends on the velocity autocorrelation and is then characterized by the memory function. The analysis of the temperature decay reveals the existence of an anomalous cooling in which the temperature may oscillate. Despite this anomalous behavior, we show that the variation of entropy remains always positive in accordance with the second law of thermodynamics.

  20. Superconductor rotor cooling system

    Science.gov (United States)

    Gamble, Bruce B.; Sidi-Yekhlef, Ahmed; Schwall, Robert E.; Driscoll, David I.; Shoykhet, Boris A.

    2002-01-01

    A system for cooling a superconductor device includes a cryocooler located in a stationary reference frame and a closed circulation system external to the cryocooler. The closed circulation system interfaces the stationary reference frame with a rotating reference frame in which the superconductor device is located. A method of cooling a superconductor device includes locating a cryocooler in a stationary reference frame, and transferring heat from a superconductor device located in a rotating reference frame to the cryocooler through a closed circulation system external to the cryocooler. The closed circulation system interfaces the stationary reference frame with the rotating reference frame.

  1. A Cool Emperor Penguin

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    哇,这只帝企鹅的胸前居然有个心形!It’s cool!(乐天:没错,它的胸前少了这幺撮毛,应该会感觉挺凉快的)cool在这里可不是“凉快”的意思,而是“酷.帅气”的意思。我们《英语大王》的英文名字就叫English Cool Kids哦!(乐天拿出一副墨镜戴上:

  2. Rapid cooled lens cell

    Science.gov (United States)

    Stubbs, David M.; Hsu, Ike C.

    1991-12-01

    This paper describes the optomechanical design, thermal analysis, fabrication, and test evaluation processes followed in developing a rapid cooled, infrared lens cell. Thermal analysis was the key engineering discipline exercised in the design phase. The effect of thermal stress on the lens, induced by rapid cooling of the lens cell, was investigated. Features of this lens cell that minimized the thermal stress will be discussed in a dedicated section. The results of thermal analysis on the selected lens cell design and the selection of the flow channel design in the heat exchanger will be discussed. Throughout the paper engineering drawings, illustrations, analytical results, and photographs of actual hardware are presented.

  3. Gas cooled fast reactor

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1972-06-01

    Although most of the development work on fast breeder reactors has been devoted to the use of liquid metal cooling, interest has been expressed for a number of years in alternative breeder concepts using other coolants. One of a number of concepts in which interest has been retained is the Gas-Cooled Fast Reactor (GCFR). As presently envisioned, it would operate on the uranium-plutonium mixed oxide fuel cycle, similar to that used in the Liquid Metal Fast Breeder Reactor (LMFBR), and would use helium gas as the coolant.

  4. Quantum thermodynamic cooling cycle

    CERN Document Server

    Palao, J P; Gordon, J M; Palao, Jose P.; Kosloff, Ronnie; Gordon, Jeffrey M.

    2001-01-01

    The quantum-mechanical and thermodynamic properties of a 3-level molecular cooling cycle are derived. An inadequacy of earlier models is rectified in accounting for the spontaneous emission and absorption associated with the coupling to the coherent driving field via an environmental reservoir. This additional coupling need not be dissipative, and can provide a thermal driving force - the quantum analog of classical absorption chillers. The dependence of the maximum attainable cooling rate on temperature, at ultra-low temperatures, is determined and shown to respect the recently-established fundamental bound based on the second and third laws of thermodynamics.

  5. Synthesis of superheavy nuclei: Obstacles and opportunities

    Directory of Open Access Journals (Sweden)

    Zagrebaev V.I.

    2015-01-01

    Full Text Available There are only 3 methods for the production of heavy and superheavy (SH nuclei, namely, fusion reactions, a sequence of neutron capture and beta(- decay and multinucleon transfer reactions. Low values of the fusion cross sections and very short half-lives of nuclei with Z<120 put obstacles in synthesis of new elements. At the same time, an important area of SH isotopes located between those produced in the cold and hot fusion reactions remains unstudied yet. This gap could be filled in fusion reactions of 48Ca with available lighter isotopes of Pu, Am, and Cm. New neutron-enriched isotopes of SH elements may be produced with the use of a 48Ca beam if a 250Cm target would be prepared. In this case we get a real chance to reach the island of stability owing to a possible beta(+ decay of 291114 and 287112 nuclei formed in this reaction with a cross section of about 0.8 pb. A macroscopic amount of the long-living SH nuclei located at the island of stability may be produced by using the pulsed nuclear reactors of the next generation only if the neutron fluence per pulse will be increased by about three orders of magnitude. Multinucleon transfer processes look quite promising for the production and study of neutron-rich heavy nuclei located in upper part of the nuclear map not reachable by other reaction mechanisms. Reactions with actinide beams and targets are of special interest for synthesis of new neutron-enriched transfermium nuclei and not-yet-known nuclei with closed neutron shell N=126 having the largest impact on the astrophysical r-process. The estimated cross sections for the production of these nuclei allows one to plan such experiments at currently available accelerators.

  6. E1 strength in N = 82 nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Hartmann, T.; Volz, S.; Babilon, M.; Mohr, P.; Vogt, K.; Zilges, A

    2003-05-19

    Recently the importance of small contributions of electric dipole strength near the particle threshold to the production rates of atomic nuclei has become evident. Prior estimates concentrated on the Giant Dipole Resonance (GDR) which dominates photoabsorption in all nuclei. Extrapolations to smaller excitation energies were assumed to be sufficiently reliable. However, new measurements reveal that collective E1 strength can be found in the threshold region.

  7. Statistical Properties of Quantum Spectra in Nuclei

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Some aspects of quantum chaos in a finite system have been studied based on the analysis of statistical behaviors of quantum spectrum in nuclei. The experiment data show the transition from order to chaos with increasing excitation energy in spherical nuclei. The dependence of the order to chaos transition on nuclear deformation and nuclear rotating is described. The influence of pairing effect on the order to chaos transition is also discussed. Some important experiment phenomena in nuclear

  8. Masses of nuclei close to the dripline

    CERN Document Server

    Herfurth, F; Beck, D; Blaum, K; Bollen, G; Kellerbauer, A G; Kluge, H J; Lunney, M D; Rodríguez, D; Schwarz, S; Sikler, G; Weber, C

    2003-01-01

    Mass measurements of radioactive nuclides are one of the cornerstones of our understanding of the nucleus. The Penning trap spectrometer ISOLTRAP performs direct mass measurements far away from the valley of stability, as well as high-precision measurements of key nuclei to anchor long decay chains. Both schemes provide valuable information on the dripline itself and on nuclei in its close vicinity. (10 refs) .

  9. Realistic level density calculation for heavy nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Cerf, N. [Institut de Physique Nucleaire, Orsay (France); Pichon, B. [Observatoire de Paris, Meudon (France); Rayet, M.; Arnould, M. [Institut d`Astronomie et d`Astrophysique, Bruxelles (Belgium)

    1994-12-31

    A microscopic calculation of the level density is performed, based on a combinatorial evaluation using a realistic single-particle level scheme. This calculation relies on a fast Monte Carlo algorithm, allowing to consider heavy nuclei (i.e., large shell model spaces) which could not be treated previously in combinatorial approaches. An exhaustive comparison of the predicted neutron s-wave resonance spacings with experimental data for a wide range of nuclei is presented.

  10. Quark Degrees of Freedom in Finite Nuclei

    CERN Document Server

    Tsushima, K; Thomas, A W; Tsushima, Kazuo; Saito, Koichi; Thomas, Anthony W.

    1996-01-01

    Properties of finite nuclei are investigated based on relativistic Hartree equations which have been derived from a relativistic quark model of the structure of bound nucleons. Nucleons are assumed to interact through the (self-consistent) exchange of scalar ($\\sigma$) and vector ($\\omega$ and and the rms charge radius in $^{40}$Ca. Calculated properties of static, closed-shell nuclei, as well as symmetric nuclear matter are compared with experimental data and with the results of Quantum Hadrodynamics (QHD).

  11. Global cloud condensation nuclei influenced by carbonaceous combustion aerosol

    Directory of Open Access Journals (Sweden)

    D. V. Spracklen

    2011-09-01

    Full Text Available Black carbon in carbonaceous combustion aerosol warms the climate by absorbing solar radiation, meaning reductions in black carbon emissions are often perceived as an attractive global warming mitigation option. However, carbonaceous combustion aerosol can also act as cloud condensation nuclei (CCN so they also cool the climate by increasing cloud albedo. The net radiative effect of carbonaceous combustion aerosol is uncertain because their contribution to CCN has not been evaluated on the global scale. By combining extensive observations of CCN concentrations with the GLOMAP global aerosol model, we find that the model is biased low (normalised mean bias = −77 % unless carbonaceous combustion aerosol act as CCN. We show that carbonaceous combustion aerosol accounts for more than half (52–64 % of global CCN with the range due to uncertainty in the emitted size distribution of carbonaceous combustion particles. The model predicts that wildfire and pollution (fossil fuel and biofuel carbonaceous combustion aerosol causes a global mean cloud albedo aerosol indirect effect of −0.34 W m−2, with stronger cooling if we assume smaller particle emission size. We calculate that carbonaceous combustion aerosol from pollution sources cause a global mean aerosol indirect effect of −0.23 W m−2. The small size of carbonaceous combustion particles from fossil fuel sources means that whilst pollution sources account for only one-third of the emitted mass they cause two-thirds of the cloud albedo aerosol indirect effect that is due to carbonaceous combustion aerosol. This cooling effect must be accounted for, along with other cloud effects not studied here, to ensure that black carbon emissions controls that reduce the high number concentrations of fossil fuel particles have the desired net effect on climate.

  12. Measure Guideline: Ventilation Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Springer, D. [Alliance for Residential Building Innovation (ARBI), David, CA (United States); Dakin, B. [Alliance for Residential Building Innovation (ARBI), David, CA (United States); German, A. [Alliance for Residential Building Innovation (ARBI), David, CA (United States)

    2012-04-01

    The purpose of this measure guideline is to provide information on a cost-effective solution for reducing cooling system energy and demand in homes located in hot-dry and cold-dry climates. This guideline provides a prescriptive approach that outlines qualification criteria, selection considerations, and design and installation procedures.

  13. Cooling of Neutron Stars

    Directory of Open Access Journals (Sweden)

    Grigorian H.

    2010-10-01

    Full Text Available We introduce the theoretical basis for modeling the cooling evolution of compact stars starting from Boltzmann equations in curved space-time. We open a discussion on observational verification of different neutron star models by consistent statistics. Particular interest has the question of existence of quark matter deep inside of compact object, which has to have a specific influence on the cooling history of the star. Besides of consideration of several constraints and features of cooling evolution, which are susceptible of being critical for internal structure of hot compact stars we have introduced a method of extraction of the mass distribution of the neutron stars from temperature and age data. The resulting mass distribution has been compared with the one suggested by supernove simulations. This method can be considered as an additional checking tool for the consistency of theoretical modeling of neutron stars. We conclude that the cooling data allowed existence of neutron stars with quark cores even with one-flavor quark matter.

  14. Elementary stochastic cooling

    Energy Technology Data Exchange (ETDEWEB)

    Tollestrup, A.V.; Dugan, G

    1983-12-01

    Major headings in this review include: proton sources; antiproton production; antiproton sources and Liouville, the role of the Debuncher; transverse stochastic cooling, time domain; the accumulator; frequency domain; pickups and kickers; Fokker-Planck equation; calculation of constants in the Fokker-Planck equation; and beam feedback. (GHT)

  15. ELECTRON COOLING FOR RHIC.

    Energy Technology Data Exchange (ETDEWEB)

    BEN-ZVI,I.

    2001-05-13

    The Accelerator Collider Department (CAD) at Brookhaven National Laboratory is operating the Relativistic Heavy Ion Collider (RHIC), which includes the dual-ring, 3.834 km circumference superconducting collider and the venerable AGS as the last part of the RHIC injection chain. CAD is planning on a luminosity upgrade of the machine under the designation RHIC II. One important component of the RHIC II upgrade is electron cooling of RHIC gold ion beams. For this purpose, BNL and the Budker Institute of Nuclear Physics in Novosibirsk entered into a collaboration aimed initially at the development of the electron cooling conceptual design, resolution of technical issues, and finally extend the collaboration towards the construction and commissioning of the cooler. Many of the results presented in this paper are derived from the Electron Cooling for RHIC Design Report [1], produced by the, BINP team within the framework of this collaboration. BNL is also collaborating with Fermi National Laboratory, Thomas Jefferson National Accelerator Facility and the University of Indiana on various aspects of electron cooling.

  16. On-chip magnetic cooling of a nanoelectronic device

    Science.gov (United States)

    Bradley, D. I.; Guénault, A. M.; Gunnarsson, D.; Haley, R. P.; Holt, S.; Jones, A. T.; Pashkin, Yu. A.; Penttilä, J.; Prance, J. R.; Prunnila, M.; Roschier, L.

    2017-04-01

    We demonstrate significant cooling of electrons in a nanostructure below 10 mK by demagnetisation of thin-film copper on a silicon chip. Our approach overcomes the typical bottleneck of weak electron-phonon scattering by coupling the electrons directly to a bath of refrigerated nuclei, rather than cooling via phonons in the host lattice. Consequently, weak electron-phonon scattering becomes an advant- age. It allows the electrons to be cooled for an experimentally useful period of time to temperatures colder than the dilution refrigerator platform, the incoming electrical connections, and the host lattice. There are efforts worldwide to reach sub-millikelvin electron temperatures in nanostructures to study coherent electronic phenomena and improve the operation of nanoelectronic devices. On-chip magnetic cooling is a promising approach to meet this challenge. The method can be used to reach low, local electron temperatures in other nanostructures, obviating the need to adapt traditional, large demagnetisation stages. We demonstrate the technique by applying it to a nanoelectronic primary thermometer that measures its internal electron temperature. Using an optimised demagnetisation process, we demonstrate cooling of the on-chip electrons from 9 mK to below 5 mK for over 1000 seconds.

  17. Sorption cooling: a valid extension to passive cooling

    NARCIS (Netherlands)

    Doornink, D.J.; Burger, J.F.; Brake, ter H.J.M.

    2008-01-01

    Passive cooling has shown to be a very dependable cryogenic cooling method for space missions. Several missions employ passive radiators to cool down their delicate sensor systems for many years, without consuming power, without exporting vibrations or producing electromagnetic interference. So for

  18. Comments on Ionization Cooling Channel Characteristics

    CERN Document Server

    Neuffer, David

    2013-01-01

    Ionization cooling channels with a wide variety of characteristics and cooling properties are being developed. These channels can produce cooling performances that are largely consistent with the ionization cooling theory developed previously. In this paper we review ionization cooling theory, discuss its application to presently developing cooling channels, and discuss criteria for optimizing cooling.

  19. Comments on Ionization Cooling Channel Characteristics

    OpenAIRE

    Neuffer, David

    2013-01-01

    Ionization cooling channels with a wide variety of characteristics and cooling properties are being developed. These channels can produce cooling performances that are largely consistent with the ionization cooling theory developed previously. In this paper we review ionization cooling theory, discuss its application to presently developing cooling channels, and discuss criteria for optimizing cooling.

  20. STOCHASTIC COOLING FOR BUNCHED BEAMS.

    Energy Technology Data Exchange (ETDEWEB)

    BLASKIEWICZ, M.

    2005-05-16

    Problems associated with bunched beam stochastic cooling are reviewed. A longitudinal stochastic cooling system for RHIC is under construction and has been partially commissioned. The state of the system and future plans are discussed.

  1. ALP hints from cooling anomalies

    CERN Document Server

    Giannotti, Maurizio

    2015-01-01

    We review the current status of the anomalies in stellar cooling and argue that, among the new physics candidates, an axion-like particle would represent the best option to account for the hinted additional cooling.

  2. Cooling devices in laser therapy

    Directory of Open Access Journals (Sweden)

    Anupam Das

    2016-01-01

    Full Text Available Cooling devices and methods are now integrated into most laser systems, with a view to protecting the epidermis, reducing pain and erythema and improving the efficacy of laser. On the basis of method employed, it can be divided into contact cooling and non-contact cooling. With respect to timing of irradiation of laser, the nomenclatures include pre-cooling, parallel cooling and post-cooling. The choice of the cooling device is dictated by the laser device, the physician′s personal choice with respect to user-friendliness, comfort of the patient, the price and maintenance costs of the device. We hereby briefly review the various techniques of cooling, employed in laser practice.

  3. Electron scattering and reactions from exotic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Karataglidis, S. [University of Johannesburg, Department of Physics, Auckland Park (South Africa); University of Melbourne, School of Physics, Victoria (Australia)

    2017-04-15

    The SCRIT and FAIR/ELISe experiments are the first to attempt to measure directly electron scattering form factors from nuclei far from stability. This will give direct information for the (one-body) charge densities of those systems, about which there is little information available. The SCRIT experiment will be taking data for medium-mass exotic nuclei, while the electron-ion collider at ELISe, when constructed, will be able to measure form factors for a wide range of exotic nuclei, as available from the radioactive ion beams produced by the FAIR experiment. Other facilities are now being proposed, which will also consider electron scattering from exotic nuclei at higher energies, to study short-range correlations in exclusive reactions. This review will consider all available information concerning the current status (largely theoretical) of electron scattering from exotic nuclei and, where possible, complement such information with equivalent information concerning the neutron densities of those exotic systems, as obtained from intermediate energy proton scattering. The issue of long- and short-range correlations will be discussed, and whether extending such studies to the exotic sector will elicit new information. (orig.)

  4. Pollen grains are efficient cloud condensation nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Pope, F D, E-mail: fdp21@cam.ac.uk [Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom)

    2010-10-15

    This letter presents a laboratory study investigating the ability of pollen grains to act as cloud condensation nuclei. The hygroscopicity of pollen is measured under subsaturated relative humidities using an electrodynamic balance. It is found, along with other results, that pollen exhibits bulk uptake of water under subsaturated conditions. Through the use of an environmental scanning electron microscope it was observed that the surface of pollen is wettable at high subsaturated humidities. The hygroscopic response of the pollen to subsaturated relative humidities is parametrized using {kappa}-Koehler theory and values of the parameter {kappa} for pollen are between 0.05 and 0.1. It is found that while pollen grains are only moderately hygroscopic, they can activate at critical supersaturations of 0.001% and lower, and thus pollen grains will readily act as cloud condensation nuclei. While the number density of pollen grains is too low for them to represent a significant global source of cloud condensation nuclei, the large sizes of pollen grains suggest that they will be an important source of giant cloud condensation nuclei. Low temperature work using the environmental scanning electron microscope indicated that pollen grains do not act as deposition ice nuclei at temperatures warmer than - 15 deg. C.

  5. Self pumping magnetic cooling

    Science.gov (United States)

    Chaudhary, V.; Wang, Z.; Ray, A.; Sridhar, I.; Ramanujan, R. V.

    2017-01-01

    Efficient thermal management and heat recovery devices are of high technological significance for innovative energy conservation solutions. We describe a study of a self-pumping magnetic cooling device, which does not require external energy input, employing Mn-Zn ferrite nanoparticles suspended in water. The device performance depends strongly on magnetic field strength, nanoparticle content in the fluid and heat load temperature. Cooling (ΔT) by ~20 °C and ~28 °C was achieved by the application of 0.3 T magnetic field when the initial temperature of the heat load was 64 °C and 87 °C, respectively. These experiments results were in good agreement with simulations performed with COMSOL Multiphysics. Our system is a self-regulating device; as the heat load increases, the magnetization of the ferrofluid decreases; leading to an increase in the fluid velocity and consequently, faster heat transfer from the heat source to the heat sink.

  6. Cooled particle accelerator target

    Science.gov (United States)

    Degtiarenko, Pavel V.

    2005-06-14

    A novel particle beam target comprising: a rotating target disc mounted on a retainer and thermally coupled to a first array of spaced-apart parallel plate fins that extend radially inwardly from the retainer and mesh without physical contact with a second array of spaced-apart parallel plate fins that extend radially outwardly from and are thermally coupled to a cooling mechanism capable of removing heat from said second array of spaced-apart fins and located within the first array of spaced-apart parallel fins. Radiant thermal exchange between the two arrays of parallel plate fins provides removal of heat from the rotating disc. A method of cooling the rotating target is also described.

  7. Water Cooled Mirror Design

    Energy Technology Data Exchange (ETDEWEB)

    Dale, Gregory E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Holloway, Michael Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pulliam, Elias Noel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-03-30

    This design is intended to replace the current mirror setup being used for the NorthStar Moly 99 project in order to monitor the target coupon. The existing setup has limited movement for camera alignment and is difficult to align properly. This proposed conceptual design for a water cooled mirror will allow for greater thermal transfer between the mirror and the water block. It will also improve positioning of the mirror by using flexible vacuum hosing and a ball head joint capable of a wide range of motion. Incorporating this design into the target monitoring system will provide more efficient cooling of the mirror which will improve the amount of diffraction caused by the heating of the mirror. The process of aligning the mirror for accurate position will be greatly improved by increasing the range of motion by offering six degrees of freedom.

  8. Magnetic entropy and cooling

    DEFF Research Database (Denmark)

    Hansen, Britt Rosendahl; Kuhn, Luise Theil; Bahl, Christian Robert Haffenden

    2010-01-01

    Some manifestations of magnetism are well-known and utilized on an everyday basis, e.g. using a refrigerator magnet for hanging that important note on the refrigerator door. Others are, so far, more exotic, such as cooling by making use of the magnetocaloric eect. This eect can cause a change...... or nitrogen liquefaction or for room-temperature cooling. The magnetocaloric eect can further be used to determine phase transition boundaries, if a change in the magnetic state occurs at the boundary.In this talk, I will introduce the magnetocaloric eect (MCE) and the two equations, which characterize...... in the temperature of a magnetic material when a magnetic eld is applied or removed. For many years, experimentalists have made use of dilute paramagnetic materials to achieve milliKelvin temperatures by use of the magnetocaloric eect. Also, research is done on materials, which might be used for hydrogen, helium...

  9. Cooling Floor AC Systems

    Science.gov (United States)

    Jun, Lu; Hao, Ding; Hong, Zhang; Ce, Gao Dian

    The present HVAC equipments for the residential buildings in the Hot-summer-and-Cold-winter climate region are still at a high energy consuming level. So that the high efficiency HVAC system is an urgently need for achieving the preset government energy saving goal. With its advantage of highly sanitary, highly comfortable and uniform of temperature field, the hot-water resource floor radiation heating system has been widely accepted. This paper has put forward a new way in air-conditioning, which combines the fresh-air supply unit and such floor radiation system for the dehumidification and cooling in summer or heating in winter. By analyze its advantages and limitations, we found that this so called Cooling/ Heating Floor AC System can improve the IAQ of residential building while keep high efficiency quality. We also recommend a methodology for the HVAC system designing, which will ensure the reduction of energy cost of users.

  10. Heating, ventilation and cooling

    CSIR Research Space (South Africa)

    Osburn, L

    2009-02-01

    Full Text Available content and is evaporated by the air stream with less moisture. Enthalpy wheels are more effective at transferring energy between the air streams as both sensible and latent heat is transferred. Ground-Coupled Heat Exchanger Ground-coupled heat... with high diurnal temperature variations. Evaporative Coolers Evaporative coolers work on the concept that the evaporation of water has a cooling effect on its immediate environment due to the latent heat that it absorbs in order to evaporate...

  11. Cooled Ion Frequency Standard.

    Science.gov (United States)

    2014-09-26

    when the cooling laser is turned off, the ions are heated by: (1) background gas collisions and (2) a plasma heating process which may be " resonant ...causes heating in our Penning traps. One way resonant particle transport is mediated is by misalignm.nt between the trap’s magnetic and electric axis...using computer solutions. The trap of Fig. 1 is noteworthy because although the inner surfaces of the trap are machined with simple conical cuts, the

  12. Electron Cooling of RHIC

    CERN Document Server

    Ben-Zvi, Ilan; Barton, Donald; Beavis, Dana; Blaskiewicz, Michael; Bluem, Hans; Brennan, Joseph M; Bruhwiler, David L; Burger, Al; Burov, Alexey; Burrill, Andrew; Calaga, Rama; Cameron, Peter; Chang, Xiangyun; Cole, Michael; Connolly, Roger; Delayen, Jean R; Derbenev, Yaroslav S; Eidelman, Yury I; Favale, Anthony; Fedotov, Alexei V; Fischer, Wolfram; Funk, L W; Gassner, David M; Hahn, Harald; Harrison, Michael; Hershcovitch, Ady; Holmes, Douglas; Hseuh Hsiao Chaun; Johnson, Peter; Kayran, Dmitry; Kewisch, Jorg; Kneisel, Peter; Koop, Ivan; Lambiase, Robert; Litvinenko, Vladimir N; MacKay, William W; Mahler, George; Malitsky, Nikolay; McIntyre, Gary; Meng, Wuzheng; Merminga, Lia; Meshkov, Igor; Mirabella, Kerry; Montag, Christoph; Nagaitsev, Sergei; Nehring, Thomas; Nicoletti, Tony; Oerter, Brian; Parkhomchuk, Vasily; Parzen, George; Pate, David; Phillips, Larry; Preble, Joseph P; Rank, Jim; Rao, Triveni; Rathke, John; Roser, Thomas; Russo, Thomas; Scaduto, Joseph; Schultheiss, Tom; Sekutowicz, Jacek; Shatunov, Yuri; Sidorin, Anatoly O; Skrinsky, Aleksander Nikolayevich; Smirnov, Alexander V; Smith, Kevin T; Todd, Alan M M; Trbojevic, Dejan; Troubnikov, Grigory; Wang, Gang; Wei, Jie; Williams, Neville; Wu, Kuo-Chen; Yakimenko, Vitaly; Zaltsman, Alex; Zhao, Yongxiang; ain, Animesh K

    2005-01-01

    We report progress on the R&D program for electron-cooling of the Relativistic Heavy Ion Collider (RHIC). This electron cooler is designed to cool 100 GeV/nucleon at storage energy using 54 MeV electrons. The electron source will be a superconducting RF photocathode gun. The accelerator will be a superconducting energy recovery linac. The frequency of the accelerator is set at 703.75 MHz. The maximum electron bunch frequency is 9.38 MHz, with bunch charge of 20 nC. The R&D program has the following components: The photoinjector and its photocathode, the superconducting linac cavity, start-to-end beam dynamics with magnetized electrons, electron cooling calculations including benchmarking experiments and development of a large superconducting solenoid. The photoinjector and linac cavity are being incorporated into an energy recovery linac aimed at demonstrating ampere class current at about 20 MeV. A Zeroth Order Design Report is in an advanced draft state, and can be found on the web at http://www.ags...

  13. Low mass integrated cooling

    CERN Document Server

    Mapelli, Alessandro

    2014-01-01

    Low mass on - detec tor cooling systems are being developed and stud ied by the Detector Technology group (PH - DT) in the CERN Physics Department in close collaboration with LHC and non - LHC experiments . Two approaches are currently being investigated. The first approach, for barrel configurations, consists in integrating the cooli ng apparatus in light mechanical structures support ing the detectors. In this case , the thermal management can be achieved either with light cooling pipes and thin plates or with a network of microchannels embedded in thin strips of silicon or polyimide . Both configuratio ns are being investigated in the context of the 2018 upgrade program of the ALICE Inner Tracking System (ITS). Moreover, it is also possible to use a s ilicon microchannel cooling device itself as structural support for the detectors and electronics. Such a configur ation has been adopted by the NA62 collaboration for the ir GigaTracKer (GTK) as well as by the LHCb collaboration for the 2018 major upgrade of...

  14. Simulation of Desiccant Cooling

    Directory of Open Access Journals (Sweden)

    Kamaruddin A.

    2017-06-01

    Full Text Available Desiccant cooling system has been an attractive topic for study lately, due to its environmentally friendly nature. It also consume less electricity and capable to be operated without refrigerant. A simulation study was conducted using 1.5 m long ducting equipped with one desiccant wheel, one sensible heat exchanger wheel, one evaporative cooling chamber and two blowers and one electric heater. The simulation study used 8.16 m/s primary air, the drying coefficient from desiccant wheel, k1=2.1 (1/s, mass transfer coefficient in evaporative cooling, k2=1.2 kg vapor/s, heat transfer coefficient in desiccant wheel, h1=4.5 W/m2 oC, and heat transfer coefficient in sensible heat exchanger wheel h2= 4.5 W/m2 oC. The simulation results show that the final temperature before entering into the air conditioning room was 25 oC and RH of 65 %, were in accordance with the Indonesian comfort index.

  15. Ultraefficient Cooling of Resonators: Beating Sideband Cooling with Quantum Control

    Science.gov (United States)

    Wang, Xiaoting; Vinjanampathy, Sai; Strauch, Frederick; Jacobs, Kurt

    2012-02-01

    There is presently a great deal of interest in cooling high-frequency micro- and nano-mechanical oscillators to their ground states. The present state of the art in cooling mechanical resonators is a version of sideband cooling, which was originally developed in the context of cooling trapped ions. Here we present a method based on quantum control that uses the same configuration as sideband cooling--coupling the resonator to be cooled to a second microwave (or optical) auxiliary resonator--but will cool significantly colder. This is achieved by applying optimal control and varying the strength of the coupling between the two resonators over a time on the order of the period of the mechanical resonator. As part of our analysis, we also obtain a method for fast, high-fidelity quantum information transfer between resonators.

  16. The Scattering of Fast Nucleons from Nuclei

    Science.gov (United States)

    Kerman, A. K.; McManus, H.; Thaler, R. M.

    2000-04-01

    The formal theory of the scattering of high-energy nucleons by nuclei is developed in terms of the nucleon-nucleon scattering amplitude. The most important approximations necessary to make numerical calculation feasible are then examined. The optical model potential is derived on this basis and compared with the optical model parameters found from experiment. The elastic scattering and polarization of nucleons from light nuclei is predicted and compared with experiment. The effect of nuclear correlations is discussed. The polarization of inelastically scattered nucleons is discussed and predictions compared with experiments. To within the validity of the approximations the experimental data on the scattering of nucleons from nuclei at energies above ˜100 Mev appears to be consistent with the theory.

  17. The scattering of fast nucleons from nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Kerman, A. K. [Massachusetts Institute of Technology, Cambridge, Massachusetts (United States); McManus, H. [Chalk River Laboratory, Chalk River, Ontario, (Canada); Thaler, R. M. [Los Alamos Scientific Laboratory, Los Alamos, New Mexico (United States)

    2000-04-10

    The formal theory of the scattering of high-energy nucleons by nuclei is developed in terms of the nucleon nucleon scattering amplitude. The most important approximations necessary to make numerical calculation feasible are then examined. The optical model potential is derived on this basis and compared with the optical model parameters found from experiment. The elastic scattering and polarization of nucleons from light nuclei is predicted and compared with experiment. The effect of nuclear correlations is discussed. The polarization of inelastically scattered nucleons is discussed and predictions compared with experiments. To within the validity of the approximations the experimental data on the scattering of nucleons from nuclei at energies above {approx}100 Mev appears to be consistent with the theory. (c) 2000 Academic Press, Inc.

  18. Reflections on cavitation nuclei in water

    DEFF Research Database (Denmark)

    Mørch, Knud Aage

    2007-01-01

    The origin of cavitation bubbles, cavitation nuclei, has been a subject of debate since the early years of cavitation research. This paper presents an analysis of a representative selection of experimental investigations of cavitation inception and the tensile strength of water. At atmospheric...... on the surface of particles and bounding walls. Such nuclei can be related to the full range of tensile strengths measured, when differences of experimental conditions are taken into consideration. The absence or presence of contamination on surfaces, as well as the structure of the surfaces, are central...... to explaining why the tensile strength of water varies so dramatically between the experiments reported. A model for calculation of the critical pressure of skin-covered free gas bubbles as well as that of interfacial gaseous nuclei covered by a skin is presented. This model is able to bridge the apparently...

  19. Nucleon localization in light and heavy nuclei

    CERN Document Server

    Zhang, C L; Nazarewicz, W

    2016-01-01

    An electron localization measure was originally introduced to characterize chemical bond structures in molecules. Recently, a nucleon localization based on Hartree-Fock densities has been introduced to investigate $\\alpha$-cluster structures in light nuclei. Compared to the local nucleonic densities, the nucleon localization function has been shown to be an excellent indicator of shell effects and cluster correlations. Using the spatial nucleon localization measure, we investigate the cluster structures in deformed light nuclei and study the emergence of fragments in fissioning heavy nuclei. To illustrate basic concepts of nucleon localization, we employ the deformed harmonic oscillator model. Realistic calculations are carried out using self-consistent nuclear density functional theory with quantified energy density functionals optimized for fission studies. We study particle densities and spatial nucleon localization distributions for deformed cluster configurations of $^{8}$Be and $^{20}$Ne, and also along...

  20. Reflections on cavitation nuclei in water

    DEFF Research Database (Denmark)

    Mørch, Knud Aage

    2007-01-01

    The origin of cavitation bubbles, cavitation nuclei, has been a subject of debate since the early years of cavitation research. This paper presents an analysis of a representative selection of experimental investigations of cavitation inception and the tensile strength of water. At atmospheric...... to explaining why the tensile strength of water varies so dramatically between the experiments reported. A model for calculation of the critical pressure of skin-covered free gas bubbles as well as that of interfacial gaseous nuclei covered by a skin is presented. This model is able to bridge the apparently...... pressure, the possibility of stabilization of free gas bubbles by a skin has been documented, but only within a range of bubble sizes that makes them responsible for tensile strengths up to about 1.5 bar, and values reaching almost 300 bar have been measured. However, cavitation nuclei can also be harbored...

  1. Alpha-cluster model of atomic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Sosin, Zbigniew; Kallunkathariyil, Jinesh [Jagiellonian University, M. Smoluchowski Institute of Physics, Krakow (Poland); Blocki, Jan [NCBJ, Theoretical Physics Division (BP2), Swierk (Poland); Lukasik, Jerzy; Pawlowski, Piotr [IFJ PAN, Krakow (Poland)

    2016-05-15

    The description of a nuclear system in its ground state and at low excitations based on the equation of state (EoS) around normal density is presented. In the expansion of the EoS around the saturation point, additional spin polarization terms are taken into account. These terms, together with the standard symmetry term, are responsible for the appearance of the α-like clusters in the ground-state configurations of the N=Z even-even nuclei. At the nuclear surface these clusters can be identified as alpha particles. A correction for the surface effects is introduced for atomic nuclei. Taking into account an additional interaction between clusters the binding energies and sizes of the considered nuclei are very accurately described. The limits of the EoS parameters are established from the properties of the α, {sup 3}He and t particles. (orig.)

  2. Shape phase mixing in critical point nuclei

    CERN Document Server

    Budaca, R

    2016-01-01

    Spectral properties of nuclei near the critical point of the quantum phase transition between spherical and axially symmetric shapes are studied in a hybrid collective model which combines the $\\gamma$-stable and $\\gamma$-rigid collective conditions through a rigidity parameter. The model in the lower and upper limits of the rigidity parameter recovers the X(5) and X(3) solutions respectively, while in the equally mixed case it corresponds to the X(4) critical point symmetry. Numerical applications of the model on nuclei from regions known for critical behavior reveal a sizable shape phase mixing and its evolution with neutron or proton numbers. The model also enables a better description of energy spectra and electromagnetic transitions for these nuclei.

  3. Statistical ensembles and fragmentation of finite nuclei

    Science.gov (United States)

    Das, P.; Mallik, S.; Chaudhuri, G.

    2017-09-01

    Statistical models based on different ensembles are very commonly used to describe the nuclear multifragmentation reaction in heavy ion collisions at intermediate energies. Canonical model results are more appropriate for finite nuclei calculations while those obtained from the grand canonical ones are more easily calculable. A transformation relation has been worked out for converting results of finite nuclei from grand canonical to canonical and vice versa. The formula shows that, irrespective of the particle number fluctuation in the grand canonical ensemble, exact canonical results can be recovered for observables varying linearly or quadratically with the number of particles. This result is of great significance since the baryon and charge conservation constraints can make the exact canonical calculations extremely difficult in general. This concept developed in this work can be extended in future for transformation to ensembles where analytical solutions do not exist. The applicability of certain equations (isoscaling, etc.) in the regime of finite nuclei can also be tested using this transformation relation.

  4. Cooling lubricants; Kuehlschmierstoffe

    Energy Technology Data Exchange (ETDEWEB)

    Pfeiffer, W. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Breuer, D. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Blome, H. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Deininger, C. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Hahn, J.U. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Kleine, H. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Nies, E. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Pflaumbaum, W. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Stockmann, R. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Willert, G. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Sonnenschein, G. [Maschinenbau- und Metall-Berufsgenossenschaft, Duesseldorf (Germany)

    1996-08-01

    As a rule, the base substances used are certain liquid hydrocarbons from mineral oils as well as from native and synthetic oils. Through the addition of further substances the cooling lubricant takes on the particular qualities required for the use in question. Employees working with cooling lubricants are exposed to various hazards. The assessment of the concentrations at the work station is carried out on the basis of existing technical rules for contact with hazardous substances. However, the application/implementation of compulsory investigation and supervision in accordance with these rules is made difficult by the fact that cooling lubricants are, as a rule, made up of complicated compound mixtures. In addition to protecting employees from exposure to mists and vapours from the cooling lubricants, protection for the skin is also of particular importance. Cooling lubricants should not, if at all possible, be brought into contact with the skin. Cleansing the skin and skin care is just as important as changing working clothes regularly, and hygiene and cleanliness at the workplace. Unavoidable emissions are to be immediately collected at the point where they arise or are released and safely disposed of. This means taking into account all sources of emissions. The programme presented in this report therefore gives a very detailed account of the individual protective measures and provides recommendations for the design of technical protection facilities. (orig./MG) [Deutsch] Als Basisstoffe dienen in der Regel bestimmte fluessige Kohlenwasserstoffverbindungen aus Mineraloelen sowie aus nativen oder synthetischen Oelen. Durch die Zugabe von weiteren Stoffen erlangt der Kuehlschmierstoff seine fuer den jeweiligen Anwendungsabfall geforderten Eigenschaften. Beschaeftigte, die mit Kuehlschmierstoffen umgehen, sind unterschiedliche Gefahren ausgesetzt. Die Beurteilung der Kuehlschmierstoffkonzentrationen in der Luft am Arbeitsplatz erfolgt auf der Grundlage bestehender

  5. Monte Carlo approaches to light nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, J.

    1990-01-01

    Significant progress has been made recently in the application of Monte Carlo methods to the study of light nuclei. We review new Green's function Monte Carlo results for the alpha particle, Variational Monte Carlo studies of {sup 16}O, and methods for low-energy scattering and transitions. Through these calculations, a coherent picture of the structure and electromagnetic properties of light nuclei has arisen. In particular, we examine the effect of the three-nucleon interaction and the importance of exchange currents in a variety of experimentally measured properties, including form factors and capture cross sections. 29 refs., 7 figs.

  6. Statistical properties of quantum spectra in nuclei

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Some aspects of quantum chaos in a finite system have been studied based on the analysis of statistical behavior of quantum spectra in nuclei.The experiment data show the transition from order to chaos with increasing excitation energy in spherical nuclei.The dependence of the order to chaos transition on nuclear deformation and nuclear rotating is described.The influence of pairing effect on the order to chaos transition is also discussed.Some important experiment phenomena in nuclear physics have been understood from the point of view of the interplay between order and chaos.

  7. Doubly magic properties in superheavy nuclei

    Institute of Scientific and Technical Information of China (English)

    HUANG Ya-Wei; ZHU Jian-Yu

    2009-01-01

    A systematic study of global properties of superheavy nuclei in the framework of the Liquid Drop Model and the Strutinsky shell correction method is performed. The evolution equilibrium deformations, TRS graphs and α-decay energies are calculated using the TRS model. The analysis covers a wide range of even-even superheavy nuclei from Z = 102 to 122. Magic numbers and their observable influence occurring in this region have been investigated. Shell closures appear at proton number Z = 114 and at neutron number N = 184.

  8. Computer Model Of Fragmentation Of Atomic Nuclei

    Science.gov (United States)

    Wilson, John W.; Townsend, Lawrence W.; Tripathi, Ram K.; Norbury, John W.; KHAN FERDOUS; Badavi, Francis F.

    1995-01-01

    High Charge and Energy Semiempirical Nuclear Fragmentation Model (HZEFRG1) computer program developed to be computationally efficient, user-friendly, physics-based program for generating data bases on fragmentation of atomic nuclei. Data bases generated used in calculations pertaining to such radiation-transport applications as shielding against radiation in outer space, radiation dosimetry in outer space, cancer therapy in laboratories with beams of heavy ions, and simulation studies for designing detectors for experiments in nuclear physics. Provides cross sections for production of individual elements and isotopes in breakups of high-energy heavy ions by combined nuclear and Coulomb fields of interacting nuclei. Written in ANSI FORTRAN 77.

  9. Medium energy hadron scattering from nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Ginocchio, J.N.; Wenes, G.

    1986-01-01

    The Glauber approximation for medium energy scattering of hadronic projectiles from nuclei is combined with the interacting boson model of nuclei to produce a transition matrix for elastic and inelastic scattering in algebraic form which includes coupling to all the intermediate states. We present closed form analytic expresions for the transition matrix elements for the three dynamical symmetries of the interacting boson model; that is for, a spherical quadrupole vibrator, a ..gamma.. unstable rotor, and both prolate and oblate axially symmetric rotors. We give examples of application of this formalism to proton scattering from /sup 154/Sm and /sup 154/Gd. 27 refs., 5 figs., 1 tab.

  10. Light nuclei from chiral EFT interactions

    Science.gov (United States)

    Navrátil, P.; Gueorguiev, V. G.; Vary, J. P.; Ormand, W. E.; Nogga, A.; Quaglioni, S.

    2008-12-01

    Recent developments in nuclear theory allow us to make a connection between quantum chromodynamics (QCD) and low-energy nuclear physics. First, chiral effective field theory (χEFT) provides a natural hierarchy to define two-nucleon ( NN), three-nucleon ( NNN), and even four-nucleon interactions. Second, ab-initio methods have been developed capable to test these interactions for light nuclei. In this contribution, we discuss ab-initio no-core shell-model (NCSM) calculations for s-shell and p-shell nuclei with NN and NNN interactions derived within χEFT.

  11. Wien filter for cooled low-energy radioactive ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Nummela, S. E-mail: saara.nummela@phys.jyu.fi; Dendooven, P.; Heikkinen, P.; Huikari, J.; Nieminen, A.; Jokinen, A.; Rinta-Antila, S.; Rubchenya, V.; Aeystoe, J

    2002-04-01

    A Wien filter for cooled radioactive ion beams has been designed at Ion Guide Isotope Separator On Line technique (IGISOL). The purpose of such device is to eliminate doubly charged ions from the mass separated singly charged ions, based on q=+2{yields}q=+1 charge exchange process in an ion cooler. The performance of the Wien filter has been tested off-line with a discharge ion source as well as on-line with a radioactive beam. The electron capture process of cooled q=+2 ions has been investigated in a radiofrequency quadrupole ion cooler with varying partial pressures of nitrogen. Also, the superasymmetric fission production yields of 68nuclei have been deduced.

  12. Laser Cooling of Molecular Anions

    CERN Document Server

    Yzombard, Pauline; Gerber, Sebastian; Doser, Michael; Comparat, Daniel

    2015-01-01

    We propose a scheme for laser cooling of negatively charged molecules. We briefly summarise the requirements for such laser cooling and we identify a number of potential candidates. A detailed computation study with C$\\_2^-$, the most studied molecular anion, is carried out. Simulations of 3D laser cooling in a gas phase show that this molecule could be cooled down to below 1 mK in only a few tens of milliseconds, using standard lasers. Sisyphus cooling, where no photo-detachment process is present, as well as Doppler laser cooling of trapped C$\\_2^-$, are also simulated. This cooling scheme has an impact on the study of cold molecules, molecular anions, charged particle sources and antimatter physics.

  13. Laser cooling of molecular anions.

    Science.gov (United States)

    Yzombard, Pauline; Hamamda, Mehdi; Gerber, Sebastian; Doser, Michael; Comparat, Daniel

    2015-05-29

    We propose a scheme for laser cooling of negatively charged molecules. We briefly summarize the requirements for such laser cooling and we identify a number of potential candidates. A detailed computation study with C_{2}^{-}, the most studied molecular anion, is carried out. Simulations of 3D laser cooling in a gas phase show that this molecule could be cooled down to below 1 mK in only a few tens of milliseconds, using standard lasers. Sisyphus cooling, where no photodetachment process is present, as well as Doppler laser cooling of trapped C_{2}^{-}, are also simulated. This cooling scheme has an impact on the study of cold molecules, molecular anions, charged particle sources, and antimatter physics.

  14. Process integration: Cooling water systems design

    CSIR Research Space (South Africa)

    Gololo, KV

    2010-10-01

    Full Text Available This paper presents a technique for grassroot design of cooling water system for wastewater minimization which incorporates the performances of the cooling towers involved. The study focuses mainly on cooling systems consisting of multiple cooling...

  15. Cooling water systems design using process integration

    CSIR Research Space (South Africa)

    Gololo, KV

    2010-09-01

    Full Text Available Cooling water systems are generally designed with a set of heat exchangers arranged in parallel. This arrangement results in higher cooling water flowrate and low cooling water return temperature thus reducing cooling tower efficiency. Previous...

  16. Observation of nuclei reassembled from demembranated Xenopus sperm nuclei and analysis of their lamina components

    Institute of Scientific and Technical Information of China (English)

    QUJIAN; CHUANMAOZHANG; 等

    1994-01-01

    A cell-free preparation obtained from extracts of activated Xenopus laevis eggs induced chromatin decondensation and nuclear formation from demembranated Xenopus sperm nuclei.Electron microscopy revealed that the reassembled nucleus had a double-layered nuclear memblane,nuclear pore complexes,and decondensed chromatin etc.Indirect immunofluorescence analysis demonstrated the presence of lamina in newly assembled nuclei.Western-blotting results showed that lamin LII was present in egg extracts and in lamina of the reassembled nuclei which were previously reported to contain only egg derived lamin LIII.

  17. Solar heating and cooling.

    Science.gov (United States)

    Duffie, J A; Beckman, W A

    1976-01-16

    We have adequate theory and engineering capability to design, install, and use equipment for solar space and water heating. Energy can be delivered at costs that are competitive now with such high-cost energy sources as much fuel-generated, electrical resistance heating. The technology of heating is being improved through collector developments, improved materials, and studies of new ways to carry out the heating processes. Solar cooling is still in the experimental stage. Relatively few experiments have yielded information on solar operation of absorption coolers, on use of night sky radiation in locations with clear skies, on the combination of a solar-operated Rankine engine and a compression cooler, and on open cycle, humidification-dehumidification systems. Many more possibilities for exploration exist. Solar cooling may benefit from collector developments that permit energy delivery at higher temperatures and thus solar operation of additional kinds of cycles. Improved solar cooling capability can open up new applications of solar energy, particularly for larger buildings, and can result in markets for retrofitting existing buildings. Solar energy for buildings can, in the next decade, make a significant contribution to the national energy economy and to the pocketbooks of many individual users. very large-aggregate enterprises in manufacture, sale, and installation of solar energy equipment can result, which can involve a spectrum of large and small businesses. In our view, the technology is here or will soon be at hand; thus the basic decisions as to whether the United States uses this resource will be political in nature.

  18. Laser Cooling of Solids

    Science.gov (United States)

    2009-01-01

    observed in a range of glasses and crystals doped with Yb3+ (ZBLANP [19–22], ZBLAN [23,24], CNBZn [9,25] BIG [25, 26], KGd(WO4)2 [9], KY(WO4)2 [9], YAG [27...Yb3+-doped fluorozirconate glass ZBLAN , Phys. Rev. B 75, 144302 (2007). [40] C. W. Hoyt, Laser Cooling in Thulium-doped Solids, Ph. D. Thesis...date, optical refrigeration research has been confined to glasses and crystals doped with rare- earth elements and direct-band semiconductors such as

  19. Magnetic moments of odd spherical nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Levon, A.I.; Fedotkin, S.N.; Vdovin, A.I.

    1986-06-01

    Using the quasiparticle-phonon model, the magnetic moments of the ground state and several of the excited states are calculated for spherical nuclei. The polarization of the core is taken into account, by means of 1+ phonons, as well as 2/sup +/ and 3/sup -/ excitations, which give a collective contribution to the magnetic moment.

  20. Neutrino Processes with Hot Nuclei in Supernovae

    Science.gov (United States)

    Dzhioev, A. A.; Vdovin, A. I.

    In this paper, we calculate cross sections for charged-current neutrino-nucleus processes occuring under presupernova conditions. To treat thermal effects we extend self-consistent Skyrme-QRPA calculations to finite temperature by using the formalism of thermo field dynamics. The numerical results are presented for the sample nuclei, $^{56}$Fe and $^{82}$Ge

  1. Fisica degli atomi e dei nuclei

    CERN Document Server

    Bernardini, Carlo

    1965-01-01

    Evidenza della struttura atomica della materia ; le proprietà degli atomi e la meccanica atomica ; gli atomi e le radiazioni elettromagnetiche ; struttura microscopica dello stato gassoso ; struttura microscopica dello stato liquido ; struttura microscopica della stato solido ; proprietà elettriche e magnetiche delle sostanze ; proprietà dei nuclei degli atomi ; le particelle elementari.

  2. Precision lifetime measurements in light exotic nuclei

    Science.gov (United States)

    McCutchan, Elizabeth

    2017-01-01

    A new generation of ab-initio calculations, based on realistic two- and three-body forces have had a profound impact on our understanding of nuclei. They have shed light on topics such as the origin of effective forces (like spin-orbit and tensor interactions) and the mechanisms behind cluster and pairing correlations. New precise data are required to both better parameterize the three body forces and to improve numerical methods. A sensitive probe of the structure of light nuclei comes from their electromagnetic transition rates. A refined Doppler Shift Attenuation Method (DSAM) will be outlined which is used to precisely measure lifetimes in light nuclei and helps to reduce and quantity systematic uncertainties in the measurement. Using this careful DSAM, we have made a series of precise measurements of electromagnetic transition strengths in Li isotopes, A =10 nuclei, and the exotic halo nucleus, 12Be. Various phenomena, such as alpha clustering and meson-exchange currents, can be investigated in these seemingly simple systems, while the collection of data spanning stable to neutron-rich, allows us to probe the influence of additional valence neutrons. This talk will report on what has been learned, and the challenges that lie in the future, both in experiment and theory, as we push to describing and measuring even more exotic systems. Work supported by the Office of Nuclear Physics, Office of Science of the U.S. Department of Energy under contract No. DE-AC02-98CH10886.

  3. Test of Pseudospin Symmetry in Deformed Nuclei

    CERN Document Server

    Ginocchio, J N; Meng, J; Zhou, S G; Zhou, Shan-Gui

    2004-01-01

    Pseudospin symmetry is a relativistic symmetry of the Dirac Hamiltonian with scalar and vector mean fields equal and opposite in sign. This symmetry imposes constraints on the Dirac eigenfunctions. We examine extensively the Dirac eigenfunctions of realistic relativistic mean field calculations of deformed nuclei to determine if these eigenfunctions satisfy these pseudospin symmetry constraints.

  4. Magnetic Dipole Sum Rules for Odd Nuclei

    CERN Document Server

    Ginocchio, J N

    1997-01-01

    Sum rules for the total- and scissors-mode M1 strength in odd-A nuclei are derived within the single-j interacting boson-fermion model. We discuss the physical content and geometric interpretation of these sum rules and apply them to ^{167}Er and ^{161}Dy. We find consistency with the former measurements but not with the latter.

  5. Spectroscopic Studies of Exotic Nuclei at ISOLDE

    CERN Multimedia

    2002-01-01

    Experiment IS50 is designed to: a) Investigate the full range of the @b strength function of heavy (A~$>$~48)~K nuclei b)~Study the decay of isomeric states in n-deficient bromine nuclei (A~=~72 and 70). The heavy K isotopes appeared to have complex decay schemes, including feeding by the @b-decay of levels having open neutron channels (Beta decay energy Q(@b) exceeds neutron binding energy S^n); in addition, a large fraction of the delayed transitions populate excited levels in the daughter nuclei. The allowed @b-decay selects states in the daughter nucleus with wave functions having a large overlap with the initial state. Hence, the @b strength functions, deduced from these deca reveal simple structures correlated to the particle-hole excitation energies in the Ca nuclei. These results are valuable for the application of the shell-model calculations far from stability. The delayed neutron spectra are measured with a large area curved scintillator in coincidence either with high resolution Ge(Li) detectors, ...

  6. Physics of the continuum of borromean nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Vaagen, J.S.; Rogde, T. [Dept. of Physics, Univ. of Bergen (Norway); Danilin, B.V. [RRC The Kurchatov Inst., Kurchatov, Moscow (Russian Federation); Ershov, S.N. [JINR, Dubna, Moscow (Russian Federation); Thompson, I.J. [Dept. of Physics, Univ. of Surrey, Guildford (United Kingdom); Zhukov, M.V. [Chalmers Univ. of Technology and Goeteborg Univ., Goeteborg (Sweden); RNBT Collaboration

    1998-06-01

    The continuum states of two-neutron halo nuclei are calculated in the method of hyperspherical harmonics. Using DWIA theory appropriate for dilute halo matter we have probed the structure of the low-lying {sup 6}He continuum via calculations of charge-exchange and inelastic scattering. (orig.)

  7. On the Elastic Scattering of Heavy Nuclei

    Energy Technology Data Exchange (ETDEWEB)

    McIntosh, J. S.; Park, S. C.; Turner, J. E.

    1960-01-01

    A program is presented for determining the differential cross-section for the elastic scattering of heavy nuclei. It utilizes the unitary property of the S-matrix and a less drastic L-dependence of the absorption than the sharp cut-off model of Blair. it is shown that experimental data can be fitted quite well. (auth)

  8. Comment on Breakup Densities of Hot Nuclei

    CERN Document Server

    Viola, V E; Natowitz, J B; Yennello, S J

    2006-01-01

    In [1,2]the observed decrease in spectral peak energies of IMFs emitted from hot nuclei was interpreted in terms of a breakup density that decreased with increasing energy. Subsequently, Raduta et al. [3] performed MMM simulations that showed decreasing spectral peaks could be obtained at constant density. In this letter we examine this apparent inconsistency.

  9. Building Atomic Nuclei with the Dirac Equation

    OpenAIRE

    Serot, Brian D.

    2003-01-01

    The relevance of the Dirac equation for computations of nuclear structure is motivated and discussed. Quantitatively successful results for medium- and heavy-mass nuclei are described, and modern ideas of effective field theory and density functional theory are used to justify them.

  10. Heavy Mesons in Nuclear Matter and Nuclei

    CERN Document Server

    Tolos, Laura; Garcia-Recio, Carmen; Molina, Raquel; Nieves, Juan; Oset, Eulogio; Ramos, Angels; Romanets, Olena; Salcedo, Lorenzo Luis; Torres-Rincon, Juan M

    2014-01-01

    Heavy mesons in nuclear matter and nuclei are analyzed within different frameworks, paying a special attention to unitarized coupled-channel approaches. Possible experimental signatures of the properties of these mesons in matter are addressed, in particular in connection with the future FAIR facility at GSI.

  11. THE COOLING OF CORONAL PLASMAS. IV. CATASTROPHIC COOLING OF LOOPS

    Energy Technology Data Exchange (ETDEWEB)

    Cargill, P. J. [Space and Atmospheric Physics, The Blackett Laboratory, Imperial College, London SW7 2BW (United Kingdom); Bradshaw, S. J., E-mail: p.cargill@imperial.ac.uk [Department of Physics and Astronomy, Rice University, Houston, TX 77005 (United States)

    2013-07-20

    We examine the radiative cooling of coronal loops and demonstrate that the recently identified catastrophic cooling is due to the inability of a loop to sustain radiative/enthalpy cooling below a critical temperature, which can be >1 MK in flares, 0.5-1 MK in active regions, and 0.1 MK in long tenuous loops. Catastrophic cooling is characterized by a rapid fall in coronal temperature, while the coronal density changes by a small amount. Analytic expressions for the critical temperature are derived and show good agreement with numerical results. This effect considerably limits the lifetime of coronal plasmas below the critical temperature.

  12. Cooling Performance of an Impingement Cooling Device Combined with Pins

    Institute of Scientific and Technical Information of China (English)

    Dongliang QUAN; Songling LIU; Jianghai LI; Gaowen LIU

    2005-01-01

    Experimental study and one dimensional model analysis were conducted to investigate cooling performance of an integrated impingement and pin fin cooling device. A typical configuration specimen was made and tested in a large scale low speed closed-looped wind tunnel. Detailed two-dimensional contour maps of the temperature and cooling effectiveness were obtained for different pressure ratios and therefore different coolant flow-rates through the tested specimen. The experimental results showed that very high cooling effectiveness can be achieved by this cooling device with relatively small amount of coolant flow. Based on the theory of transpiration cooling in porous material, a one dimensional heat transfer model was established to analyze the effect of various parameters on cooling effectiveness. It was found from this model that the variation of heat transfer on the gas side, including heat transfer coefficient and film cooling effectiveness, of the specimen created much more effect on its cooling effectiveness than that of the coolant side. The predictions of the one-dimensional mode were compared and agreed well with the experimental data.

  13. Spectroscopic factors for two-proton radioactive nuclei

    Indian Academy of Sciences (India)

    Chinmay Basu

    2004-11-01

    Spectroscopic factors for two-proton emitting nuclei are discussed in the framework of the BCS (Bardeen–Cooper–Schriefer) model. Calculations carried out for the two-proton unstable 45Fe, 48Ni and 54Zn nuclei are presented.

  14. Whole-Cell Properties of Cerebellar Nuclei Neurons In Vivo

    NARCIS (Netherlands)

    Canto, Cathrin B; Witter, L.; De Zeeuw, C.I.

    2016-01-01

    Cerebellar nuclei neurons integrate sensorimotor information and form the final output of the cerebellum, projecting to premotor brainstem targets. This implies that, in contrast to specialized neurons and interneurons in cortical regions, neurons within the nuclei encode and integrate complex

  15. Electronic cooling using thermoelectric devices

    Energy Technology Data Exchange (ETDEWEB)

    Zebarjadi, M., E-mail: m.zebarjadi@rutgers.edu [Department of Mechanical and Aerospace Engineering, Rutgers University, Piscataway, New Jersey 08854 (United States); Institute of Advanced Materials, Devices, and Nanotechnology, Rutgers University, Piscataway, New Jersey 08854 (United States)

    2015-05-18

    Thermoelectric coolers or Peltier coolers are used to pump heat in the opposite direction of the natural heat flux. These coolers have also been proposed for electronic cooling, wherein the aim is to pump heat in the natural heat flux direction and from hot spots to the colder ambient temperature. In this manuscript, we show that for such applications, one needs to use thermoelectric materials with large thermal conductivity and large power factor, instead of the traditionally used high ZT thermoelectric materials. We further show that with the known thermoelectric materials, the active cooling cannot compete with passive cooling, and one needs to explore a new set of materials to provide a cooling solution better than a regular copper heat sink. We propose a set of materials and directions for exploring possible materials candidates suitable for electronic cooling. Finally, to achieve maximum cooling, we propose to use thermoelectric elements as fins attached to copper blocks.

  16. Optical stochastic cooling in Tevatron

    CERN Document Server

    Lebedev, V

    2012-01-01

    Intrabeam scattering is the major mechanism resulting in a growth of beam emittances and fast luminosity degradation in the Tevatron. As a result in the case of optimal collider operation only about 40% of antiprotons are used to the store end and the rest are discarded. Beam cooling is the only effective remedy to increase the particle burn rate and, consequently, the luminosity. Unfortunately neither electron nor stochastic cooling can be effective at the Tevatron energy and bunch density. Thus the optical stochastic cooling (OSC) is the only promising technology capable to cool the Tevatron beam. Possible ways of such cooling implementation in the Tevatron and advances in the OSC cooling theory are discussed in this paper. The technique looks promising and potentially can double the average Tevatron luminosity without increasing its peak value and the antiproton production.

  17. Incidence of centrally positioned nuclei in mouse masticatory muscle fibers

    DEFF Research Database (Denmark)

    Vilmann, A; Vilmann, H; Kirkeby, S

    1989-01-01

    Cross-sections of normal digastric, temporalis and masseter muscles from 7- and 30-week-old mice were studied for centrally positioned nuclei. Such nuclei were inhomogeneously distributed throughout each muscle and varied markedly between specimens. The incidence of centrally positioned nuclei......, the frequency in a given muscle was apparently age-independent. A connection between fiber type and centrally positioned nuclei is suggested....

  18. Electron Cooling Experiments in CSR

    CERN Document Server

    Xiaodong, Yang

    2011-01-01

    The six species heavy ion beam was accumulated with the help of electron cooling in the main ring of Cooler Storage Ring of Heavy Ion Research Facility in Lanzhou(HIRFL-CSR), the ion beam accumulation dependence on the parameters of cooler was investigated experimentally. The 400MeV/u 12C6+ and 200MeV/u 129Xe54+ was stored and cooled in the experimental ring CSRe, the cooling force was measured in different condition.

  19. Radiative cooling for thermophotovoltaic systems

    Science.gov (United States)

    Zhou, Zhiguang; Sun, Xingshu; Bermel, Peter

    2016-09-01

    Radiative cooling has recently garnered a great deal of attention for its potential as an alternative method for photovoltaic thermal management. Here, we will consider the limits of radiative cooling for thermal management of electronics broadly, as well as a specific application to thermal power generation. We show that radiative cooling power can increase rapidly with temperature, and is particularly beneficial in systems lacking standard convective cooling. This finding indicates that systems previously operating at elevated temperatures (e.g., 80°C) can be passively cooled close to ambient under appropriate conditions with a reasonable cooling area. To examine these general principles for a previously unexplored application, we consider the problem of thermophotovoltaic (TPV) conversion of heat to electricity via thermal radiation illuminating a photovoltaic diode. Since TPV systems generally operate in vacuum, convective cooling is sharply limited, but radiative cooling can be implemented with proper choice of materials and structures. In this work, realistic simulations of system performance are performed using the rigorous coupled wave analysis (RCWA) techniques to capture thermal emitter radiation, PV diode absorption, and radiative cooling. We subsequently optimize the structural geometry within realistic design constraints to find the best configurations to minimize operating temperature. It is found that low-iron soda-lime glass can potentially cool the PV diode by a substantial amount, even to below ambient temperatures. The cooling effect can be further improved by adding 2D-periodic photonic crystal structures. We find that the improvement of efficiency can be as much as an 18% relative increase, relative to the non-radiatively cooled baseline, as well as a potentially significant improvement in PV diode lifetime.

  20. To Be Cool or Uncool?

    Institute of Scientific and Technical Information of China (English)

    袁会珍

    2007-01-01

    The western world has always been divided into two types of people-the cool and the uncool. It is a division that __1__ in school. The cool kids are good at __2__. They are __3__ with the opposite sex. They are good-looking and people want to __4__ their style. They can do their homework but they don't make a big effort. That would __5__ be cool.

  1. Electron cooling experiments in CSR

    Institute of Scientific and Technical Information of China (English)

    PARKHOMCHUK; Vasily; REVA; Vladimir

    2011-01-01

    The six species heavy ion beam was accumulated with the help of electron cooling in the main ring of Cooler Storage Ring of Heavy Ion Research Facility in Lanzhou (HIRFL-CSR). The ion beam accumulation dependence on the parameters of cooler was investigated experimentally. The 400 MeV/u 12C6+ and 200 MeV/u 129Xe54+ were stored and cooled in the experimental ring CSRe, and the cooling force was measured in different conditions.

  2. Workshop 4 Converter cooling & recuperation

    Science.gov (United States)

    Iles, Peter; Hindman, Don

    1995-01-01

    Cooling the PV converter increases the overall TPV system efficiency, and more than offsets the losses incurred in providing cooling systems. Convective air flow methods may be sufficient, and several standard water cooling systems, including thermo-syphon radiators, capillary pumps or microchannel plates, are available. Recuperation is used to increase system efficiency, rather than to increase the emitter temperature. Recuperators operating at comparable high temperatures, such as in high temperature turbines have worked effectively.

  3. Stochastic cooling technology at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Pasquinelli, R.J. E-mail: pasquin@fnal.gov

    2004-10-11

    The first antiproton cooling systems were installed and commissioned at Fermilab in 1984-1985. In the interim period, there have been several major upgrades, system improvements, and complete reincarnation of cooling systems. This paper will present some of the technology that was pioneered at Fermilab to implement stochastic cooling systems in both the Antiproton Source and Recycler accelerators. Current performance data will also be presented.

  4. Direct cooled power electronics substrate

    Science.gov (United States)

    Wiles, Randy H [Powell, TN; Wereszczak, Andrew A [Oak Ridge, TN; Ayers, Curtis W [Kingston, TN; Lowe, Kirk T [Knoxville, TN

    2010-09-14

    The disclosure describes directly cooling a three-dimensional, direct metallization (DM) layer in a power electronics device. To enable sufficient cooling, coolant flow channels are formed within the ceramic substrate. The direct metallization layer (typically copper) may be bonded to the ceramic substrate, and semiconductor chips (such as IGBT and diodes) may be soldered or sintered onto the direct metallization layer to form a power electronics module. Multiple modules may be attached to cooling headers that provide in-flow and out-flow of coolant through the channels in the ceramic substrate. The modules and cooling header assembly are preferably sized to fit inside the core of a toroidal shaped capacitor.

  5. Cooling clothing utilizing water evaporation

    DEFF Research Database (Denmark)

    Sakoi, Tomonori; Tominaga, Naoto; Melikov, Arsen Krikor

    2014-01-01

    We developed cooling clothing that utilizes water evaporation to cool the human body and has a mechanism to control the cooling intensity. Clean water was supplied to the outer surface of the T-shirt of the cooling clothing, and a small fan was used to enhance evaporation on this outer surface...... temperature ranging from 27.4 to 30.7 °C to establish a suitable water supply control method. A water supply control method that prevents water accumulation in the T-shirt and water dribbling was validated; this method is established based on the concept of the water evaporation capacity under the applied...

  6. Regeneratively Cooled Porous Media Jacket

    Science.gov (United States)

    Mungas, Greg (Inventor); Fisher, David J. (Inventor); London, Adam Pollok (Inventor); Fryer, Jack Merrill (Inventor)

    2013-01-01

    The fluid and heat transfer theory for regenerative cooling of a rocket combustion chamber with a porous media coolant jacket is presented. This model is used to design a regeneratively cooled rocket or other high temperature engine cooling jacket. Cooling jackets comprising impermeable inner and outer walls, and porous media channels are disclosed. Also disclosed are porous media coolant jackets with additional structures designed to transfer heat directly from the inner wall to the outer wall, and structures designed to direct movement of the coolant fluid from the inner wall to the outer wall. Methods of making such jackets are also disclosed.

  7. Flux of cosmic ray heavy nuclei enders behind low shielding

    CERN Document Server

    Allkofer, O C

    1975-01-01

    The authors investigate the number of stopping nuclei per cm/sup 3/ tissue hour as a function of absorbing material thickness. Fragmentation probabilities of heavy nuclei were deduced from the measured attenuation of the heavy nuclei flux in the atmosphere. Comparison is made with the results of the Biostack I experiment on board Apollo 16. (11 refs).

  8. Fluid cooled electrical assembly

    Science.gov (United States)

    Rinehart, Lawrence E.; Romero, Guillermo L.

    2007-02-06

    A heat producing, fluid cooled assembly that includes a housing made of liquid-impermeable material, which defines a fluid inlet and a fluid outlet and an opening. Also included is an electrical package having a set of semiconductor electrical devices supported on a substrate and the second major surface is a heat sink adapted to express heat generated from the electrical apparatus and wherein the second major surface defines a rim that is fit to the opening. Further, the housing is constructed so that as fluid travels from the fluid inlet to the fluid outlet it is constrained to flow past the opening thereby placing the fluid in contact with the heat sink.

  9. ATLAS' major cooling project

    CERN Multimedia

    2005-01-01

    In 2005, a considerable effort has been put into commissioning the various units of ATLAS' complex cryogenic system. This is in preparation for the imminent cooling of some of the largest components of the detector in their final underground configuration. The liquid helium and nitrogen ATLAS refrigerators in USA 15. Cryogenics plays a vital role in operating massive detectors such as ATLAS. In many ways the liquefied argon, nitrogen and helium are the life-blood of the detector. ATLAS could not function without cryogens that will be constantly pumped via proximity systems to the superconducting magnets and subdetectors. In recent weeks compressors at the surface and underground refrigerators, dewars, pumps, linkages and all manner of other components related to the cryogenic system have been tested and commissioned. Fifty metres underground The helium and nitrogen refrigerators, installed inside the service cavern, are an important part of the ATLAS cryogenic system. Two independent helium refrigerators ...

  10. A novel ion cooling trap for multi-reflection time-of-flight mass spectrograph

    CERN Document Server

    Ito, Y; Wada, M; Naimi, S; Smorra, C; Sonoda, T; Mita, H; Takamine, A; Okada, K; Ozawa, A; Wollnik, H

    2013-01-01

    A radiofrequency quadrupole ion trap system for use with a multi-reflection time-of-flight mass spectrograph (MRTOF) for short-lived nuclei has been developed. The trap system consists of two different parts, an asymmetric taper trap and a flat trap. The ions are cooled to a sufficient small bunch for precise mass measurement with MRTOF in only 2 ms cooling time in the flat trap, then orthogonally ejected to the MRTOF for mass analysis. A trapping efficiency of ~27% for 23Na+ and ~5.1% for 7Li+ has been achieved.

  11. Air cooled absorption chillers for solar cooling applications

    Science.gov (United States)

    Biermann, W. J.; Reimann, R. C.

    1982-03-01

    The chemical composition of a 'best' absorption refrigerant system is identified, and those properties of the system necessary to design hot water operated, air cooled chilling equipment are determined. Air cooled chillers from single family residential sizes into the commercial rooftop size range are designed and operated.

  12. Population of rotational bands in superheavy nuclei

    Directory of Open Access Journals (Sweden)

    Antonenko N.V.

    2012-02-01

    Full Text Available Using the statistical approach, we study the population of ground-state rotational bands of superheavy nuclei produced in the fusion-evaporation reactions 208Pb(48Ca, 2n254No, 206Pb(48Ca, 2n252No, and 204Hg(48Ca, 2n250Fm. We calculate relative intensities of E2-transitions between the rotational states and entry spin distributions of the residual nuclei, evaporation residue cross sections, and excitation functions for these reactions. Fermi-gas model is used for the calculation of level density, and damping of shell effects both with excitation energy and angular momentum is taking into account. The results are in a good agreement with the experiment data.

  13. DAPI fluorescence in nuclei isolated from tumors.

    Science.gov (United States)

    Krishan, Awtar; Dandekar, Payal D

    2005-08-01

    In DNA histograms of some human solid tumors stained with nuclear isolation medium--4,6-diamidino-2-phenylindole dihydrochloride (NIM-DAPI), the coefficient of variation (CV) of the G0/G1 peak was broad, and in nuclear volume vs DNA scattergrams, a prominent slope was seen. To determine the cause for this, nuclei from frozen breast tumors were stained with NIM-DAPI and analyzed after dilution or resuspension in PBS. In two-color (blue vs red) analysis, most of the slope and broad CV was due to red fluorescence of nuclei stained with NIM-DAPI, which was reduced on dilution or resuspension in PBS, resulting in elimination of the slope and tightening of the CV.

  14. Clustering in stable and exotic nuclei

    CERN Document Server

    Beck, C

    2016-01-01

    Since the pioneering discovery of molecular resonances in the 12C+12C reaction more than half a century ago a great deal of research work has been undertaken in alpha clustering. Our knowledge on physics of nuclear molecules has increased considerably and nuclear clustering remains one of the most fruitful domains of nuclear physics, facing some of the greatest challenges and opportunities in the years ahead. The occurrence of "exotic" shapes and Bose-Einstein alpha condensates in light N=Z alpha-conjugate nuclei is investigated. Various approaches of the superdeformed and hyperdeformed bands associated with quasimolecular resonant structures are presented. Evolution of clustering from stability to the drip-lines is examined: clustering aspects are, in particular, discussed for light exotic nuclei with large neutron excess such as neutron-rich Oxygen isotopes with their complete spectroscopy.

  15. Shell model for warm rotating nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Matsuo, M.; Yoshida, K. [Kyoto Univ. (Japan); Dossing, T. [Univ. of Copenhagen (Denmark)] [and others

    1996-12-31

    Utilizing a shell model which combines the cranked Nilsson mean-field and the residual surface and volume delta two-body forces, the authors discuss the onset of rotational damping in normal- and super-deformed nuclei. Calculation for a typical normal deformed nucleus {sup 168}Yb indicates that the rotational damping sets in at around 0.8 MeV above the yrast line, and about 30 rotational bands of various length exists at a given rotational frequency, in overall agreement with experimental findings. It is predicted that the onset of rotational damping changes significantly in different superdeformed nuclei due to the variety of the shell gaps and single-particle orbits associated with the superdeformed mean-field.

  16. Collective properties of drip-line nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Hamamoto, I. [Univ. of Lund (Sweden); Sagawa, H. [Univ. of Aizu, Fukushima (Japan)

    1996-12-31

    Performing the spherical Hartree-Fock (HF) calculations with Skyrme interactions and, then, using RPA solved in the coordinate space with the Green`s function method, the authors have studied the effect of the unique shell structure as well as the very low particle threshold on collective modes in drip line nuclei. In this method a proper strength function in the continuum is obtained, though the spreading width of collective modes is not included. They have examined also one-particle resonant states in the obtained HF potential. Unperturbed particle-hole (p-h) response functions are carefully studied, which contain all basic information on the exotic behaviour of the RPA strength function in drip line nuclei.

  17. Disappearance of collective motion in hot nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Santonocito, D.; Piattelli, P.; Agodi, C.; Alba, R.; Bellia, G.; Coniglione, R.; Del Zoppo, A.; Finocchiaro, P.; Hongmei, F.; Maiolino, C.; Migneco, E.; Sapienza, P. [INFN-LNS, Laboratori Nazionali del Sud, Catania (Italy); Blumenfeld, Y.; Delaunay, F.; Frascaria, N.; Lima, V.; Scarpaci, J. [Institut de Physique Nucleaire, IN2P3-CNRS, 91 - Orsay (France); Migneco, E. [Catania Univ., Dipartimento di Fisica (Italy)

    2003-07-01

    The evolution of the GDR {gamma} yield for excitation energies between 160 and 300 MeV has been investigated in nuclei of mass A {approx} 126 through the reactions {sup 116}Sn + {sup 12}C and {sup 24}Mg at 17 and 23 A*MeV. Gamma-rays were detected with MEDEA array in coincidence with residues detected in MACISTE. The evolution of the GDR parameters has been investigated as a function of the linear momentum transferred to the fused system. This procedure allowed us to select hot nuclei produced in incomplete fusion reactions with different excitation energies. The analysis of the {gamma} spectra and their comparison with CASCADE calculations is presented. Results suggest a saturation of the GDR yield between 200 and 300 MeV excitation energy. (authors)

  18. Simulation of nuclei morphologies for binary alloy

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We study the critical nuclei morphologies of a binary alloy by the string method. The dynamic equation of the string, connecting the metastable phase (liquid) and stable phase (solid), is governed by Helmholtz free energy for the binary alloy system at a given temperature. The stationary string through the critical nucleus (saddle point) is obtained if the relaxation time of the string is su?ciently large. The critical nucleus radius and energy barrier to nucleation of a pure alloy with isotropic interface energy in two and three dimensions are calculated, which are consistent with the classical nucleation theory. The critical nuclei morphologies are sensitive to the anisotropy strength of interface energy and interface thickness of alloy in two and three dimensions. The critical nucleus and energy barrier to nucleation become smaller if the anisotropy strength of the interface energy is increased, which means that it is much easier to form a stable nucleus if the anisotropy of the interface energy is considered.

  19. Gamma spectroscopy of neutron rich actinide nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Birkenbach, Benedikt; Geibel, Kerstin; Vogt, Andreas; Hess, Herbert; Reiter, Peter; Steinbach, Tim; Schneiders, David [Koeln Univ. (Germany). IKP; Collaboration: AGATA-Collaboration

    2013-07-01

    Excited states in neutron-rich actinide Th and U nuclei were investigated after multi nucleon transfer reactions employing the AGATA demonstrator and PRISMA setup at LNL (INFN, Italy). A primary {sup 136}Xe beam of 1 GeV hitting a {sup 238}U target was used to produce the nuclei of interest. Beam-like reaction products of Xe- and Ba isotopes after neutron transfer were selected by the PRISMA spectrometer. The recoil like particles were registered by a MCP detector inside the scattering chamber. Coincident γ-rays from excited states in beam and target like particles were measured with the position sensitive AGATA HPGe detectors. Improved Doppler correction and quality of the γ-spectra is based on the novel γ-ray tracking technique which was successfully exploited. First results on the collective properties of various Th and U isotopes are discussed.

  20. Isospin Mixing In N $\\approx$ Z Nuclei

    CERN Multimedia

    Srnka, D; Versyck, S; Zakoucky, D

    2002-01-01

    Isospin mixing in N $\\approx$ Z nuclei region of the nuclear chart is an important phenomenon in nuclear physics which has recently gained theoretical and experimental interest. It also forms an important nuclear physics correction in the precise determination of the $ft$-values of superallowed 0$^+ \\rightarrow 0^+ \\beta$- transitions. The latter are used in precision tests of the weak interaction from nuclear $\\beta$- decay. We propose to experimentally measure isospin mixing into nuclear ground states in the N $\\approx$ Z region by determining the isospin forbidden Fermi-component in the Gamow-Teller dominated $J^{\\pi} \\rightarrow J^{\\pi} \\beta$- transitions through the observation of anisotropic positron emission from oriented nuclei. First measurements were carried out with $^{71}$As and are being analyzed now.

  1. Antiproton Induced Fission and Fragmentation of Nuclei

    CERN Multimedia

    2002-01-01

    The annihilation of slow antiprotons with nuclei results in a large highly localized energy deposition primarily on the nuclear surface. \\\\ \\\\ The study of antiproton induced fission and fragmentation processes is expected to yield new information on special nuclear matter states, unexplored fission modes, multifragmentation of nuclei, and intranuclear cascades.\\\\ \\\\ In order to investigate the antiproton-nucleus interaction and the processes following the antiproton annihilation at the nucleus, we propose the following experiments: \\item A)~Measurement of several fragments from fission and from multifragmentation in coincidence with particle spectra, especially neutrons and kaons. \\item B)~Precise spectra of $\\pi$, K, n, p, d and t with time-of-flight techniques. \\item C)~Installation of the Berlin 4$\\pi$ neutron detector with a 4$\\pi$ Si detector placed inside for fragments and charged particles. This yields neutron multiplicity distributions and consequently distributions of thermal excitation energies and...

  2. Formation of Ionization-Cone Structures in Active Galactic Nuclei: I. Stationary Model and Linear Stability Analysis

    CERN Document Server

    Afanasiev, V L; Khrapov, S S; Moiseev, A V; Mustsevoy, V V

    2007-01-01

    We discuss causes of the formation of the observed kinematics and morphology of cones of ionized matter in the neighborhood of the nuclei of Seyfert galaxies. The results of linear stability analysis of an optically thin conic jet where radiation cooling and gravity play an important part are reported. The allowance for radiation cooling is shown to result in strong damping of all acoustic modes and to have insignificant effect on unstable surface Kelvin--Helmholtz modes. In the case of waveguide--resonance internal gravity modes radiative cooling suppresses completely the instability of waves propagating away from the ejection source and, vice versa, reduces substantially the growth time scale of unstable sourceward propagating modes. The results obtained can be used to study ionization cones in Seyfert galaxies with radio jets. In particular, our analysis shows that surface Kelvin--Helmholtz modes and volume harmonics are capable of producing regular features observed in optical emission-line images of such...

  3. Electromagnetic interactions with nuclei and nucleons

    Energy Technology Data Exchange (ETDEWEB)

    Thornton, S.T.; Sealock, R.M.

    1990-11-10

    This report discusses the following topics: general LEGS work; photodisintegration of the deuteron; progress towards other experiments; LEGS instrumentation; major LEGS software projects; NaI detector system; nucleon detector system; waveshifting fibers; EGN prototype detector for CEBAF; photon beam facility at CEBAF; delta electroproduction in nuclei; quasielastic scattering and excitation of the Delta by {sup 4}He(e,e{prime}); and quasielastic scattering at high Q{sup 2}.

  4. Spin-isospin resonances in nuclei

    NARCIS (Netherlands)

    Fujiwara, M; Akimune, H; Daito, [No Value; Ejiri, H; Fujita, Y; Greenfield, MB; Harakeh, MN; Inomata, T; Janecke, J; Nakayama, S; Takemura, N; Tamii, A; Tanaka, M; Toyokawa, H; Yosoi, M

    1996-01-01

    Spin-isospin excitations in nuclei have been investigated via the (He-3,t) reaction at 450 MeV. The volume integrals of the effective interactions J(sigma tau) and J(tau) for the (He-3,t) reaction at 450 MeV have been empirically determined to be 172+/-17 MeV-fm(3) and 53+/-5 MeV-fm(3), respectively

  5. Understanding active galactic nuclei: peeling the onion.

    Science.gov (United States)

    Krolik, J. H.

    A brief review is presented of selected current problems in understanding active galactic nuclei, with special emphasis on the contributions that X-ray observations can make. Questions having to do with: how the character of the host galaxy influences nuclear activity; emission line regions; the border between the nucleus and the stellar portion of the active galaxy; radiation of the nonthermal continuum; and the possible existence of an accretion disk are touched upon.

  6. Light nuclei production in heavy ion collisions

    CERN Document Server

    Khan, K H; Wazir, Z; Khan, E U; Haseeb, Mahnaz Q; Ajaz, M

    2009-01-01

    Light nuclei production as a result of nuclear coalescence effect can give some signals on final state of Quark Gluon Plasma formation. We are studying the behavior of nuclear modification factor as a function of different variables using the simulated data coming from the FASTMC generator. This data is necessary to extract information on coalescence mechanism from experimental data on high energy nuclear-nuclear interactions.

  7. SEARCH FOR NUCLEI CONTAINING TWO STRANGE QUARKS.

    Energy Technology Data Exchange (ETDEWEB)

    MAY,M.

    1997-10-13

    This paper discusses a search for nuclei containing two strange quarks performed at Brookhaven National Laboratory. The goals and approach of experiment E885 are reviewed. Preliminary missing mass spectra for a subset of the data are presented, showing sensitivity for {Xi} hypernuclei and H particle searches. Existence of an angular correlation between pions in the sequential decay of {Lambda}{Lambda} hypernuclei is suggested on theoretical grounds.

  8. Search for nuclei containing two strange quarks

    Energy Technology Data Exchange (ETDEWEB)

    May, M.

    1997-12-31

    This paper discusses a search for nuclei containing two strange quarks performed at Brookhaven National Laboratory. The goals and approach of experiment E885 are reviewed. Preliminary missing mass spectra for a subset of the data are presented, showing sensitivity for {Xi} hypernuclei and H particle searches. Existence of an angular correlation between pions in the sequential decay of {Lambda}{Lambda} hypernuclei is suggested on theoretical grounds.

  9. Green's function calculations of light nuclei

    Science.gov (United States)

    Sun, ZhongHao; Wu, Qiang; Xu, FuRong

    2016-09-01

    The influence of short-range correlations in nuclei was investigated with realistic nuclear force. The nucleon-nucleon interaction was renormalized with V lowk technique and applied to the Green's function calculations. The Dyson equation was reformulated with algebraic diagrammatic constructions. We also analyzed the binding energy of 4He, calculated with chiral potential and CD-Bonn potential. The properties of Green's function with realistic nuclear forces are also discussed.

  10. AMS with light nuclei at small accelerators

    Science.gov (United States)

    Stan-Sion, C.; Enachescu, M.

    2017-06-01

    AMS applications with lighter nuclei are presented. It will be shown how Carbon-14, Boron-10, Beryllium-10, and Tritium-3 can be used to provide valuable information in forensic science, environmental physics, nuclear pollution, in material science and for diagnose of the plasma confinement in fusion reactors. Small accelerators are reliable, efficient and possess the highest ion beam transmissions that confer high precision in measurements.

  11. Fayans functional for deformed nuclei. Uranium region

    CERN Document Server

    Tolokonnikov, S V; Kortelainen, M; Lutostansky, Yu S; Saperstein, E E

    2015-01-01

    Fayans energy density functional (EDF) FaNDF^0 has been applied to the nuclei around uranium region. Ground state characteristics of the Th, U and Pu isotopic chains, up to the two-neutron drip line, are found and compared with predictions from several Skyrme EDFs. The two-neutron drip line is found for FaNDF^0, SLy4 and SkM^* EDFs for a set of elements with even proton number, from Pb up to Fm.

  12. A new data evaluation approach for mass measurements of exotic nuclei performed with isochronous mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Diwisch, M.; Fabian, B.; Kuzminchuk, N. [Justus Liebig University Giessen (Germany); Knoebel, R.; Geissel, H.; Plass, W.R.; Scheidenberger, C.; Boutin, D.; Brandau, C.; Chen, L. [Justus Liebig University Giessen (Germany); GSI, Darmstadt (Germany); Patyk, Z. [Soltan Institute for Nuclear Studies, Warszawa (Poland); Weick, H.; Beckert, K.; Bosch, F.; Dimopoulou, C.; Dolinskii, A.; Klepper, O.; Kozhuharov, C.; Kurcewicz, J.; Litvinov, S.A.; Litvinov, Yu.A.; Mazzocco, M.; Muenzenberg, G.; Nociforo, C.; Nolden, F.; Steck, M.; Winkler, M. [GSI, Darmstadt (Germany); Cullen, I.J.; Liu, Z.; Walker, P.M. [University of Surrey, Guildford (United Kingdom); Hausmann, M.; Montes, F. [Michigan State University, East Lansing (United States); Musumarra, A. [Laboratori Nazionali del Sud, INFN Catania (Italy); Nakajima, S.; Suzuki, T.; Yamaguchi, T. [Saitama University, Saitama (Japan); Ohtsubo, T. [Niigata University, Niigata (Japan); Ozawa, A. [University of Tsukuba, Tsukuba (Japan); Sun, B. [GSI, Darmstadt (Germany); School of Physics, Peking University, Beijing (China); Winckler, N. [Max Planck Institut fuer Kernphysik, Heidelberg (Germany)

    2014-07-01

    The Isochronous Mass Spectrometry (IMS) and Schottky Mass Spectrometry (SMS) are powerful tools to measure masses of rare exotic nuclei in a storage ring. While the SMS method provides very high accuracies it does not give access to rare isotopes with lifetimes in the sub second range because beam cooling has to be performed for a few seconds before the measurements start. As a complementary method IMS can be used without beam cooling to reach isotopes with lifetimes of only a few 10 μs. As a drawback of the IMS method one cannot achieve the high mass accuracy of the SMS method until now. For the data evaluation of the SMS data a correlation matrix method has been successfully applied in the past. In order to improve the accuracy of the IMS measurements the same method will now be used, which will allow to combine and to correlate data from different IMS measurements with each other. Applying this method to the analysis of previous experiments with uranium fission fragments at the FRS-ESR facility at GSI and to future experiments, will increase the accuracy of the IMS method and may lead to new mass values with reasonable accuracies for very rare and important nuclei for nuclear astrophysics such as {sup 130}Cd, which were not accessible before.

  13. Fusion excitation functions involving transitional nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Rehm, K.E.; Jiang, C.L.; Esbensen, H. [and others

    1995-08-01

    Measurements of fusion excitation functions involving transitional nuclei {sup 78}Kr and {sup 100}Mo showed a different behavior at low energies, if compared to measurements with {sup 86}Kr and {sup 92}Mo. This points to a possible influence of nuclear structure on the fusion process. One way to characterize the structure of vibrational nuclei is via their restoring force parameters C{sub 2} which can be calculated from the energy of the lowest 2{sup +} state and the corresponding B(E2) value. A survey of the even-even nuclei between A = 28-150 shows strong variations in C{sub 2} values spanning two orders of magnitude. The lowest values for C{sub 2} are observed for {sup 78}Kr, {sup 104}Ru and {sup 124}Xe followed by {sup 74,76}Ge, {sup 74,76}Se, {sup 100}Mo and {sup 110}Pd. In order to learn more about the influence of {open_quotes}softness{close_quotes} on the sub-barrier fusion enhancement, we measured cross sections for evaporation residue production for the systems {sup 78}Kr + {sup 104}Ru and {sup 78}Kr + {sup 76}Ge with the gas-filled magnet technique. For both systems, fusion excitation functions involving the closed neutron shell nucleus {sup 86}Kr were measured previously. The data are presently being analyzed.

  14. Ice Nuclei Measurements From AMAZE-08

    Science.gov (United States)

    Prenni, A. J.; Petters, M. D.; Demott, P. J.; Kreidenweis, S. M.

    2008-12-01

    The Amazon Basin is the largest intact tropical forest in the world, covering four million square kilometers. With large emissions of gases and particulate matter, this ecosystem plays an important role in the global atmosphere. Assessing gaseous and particulate emissions from the Amazon Basin and the climatic effects of these emissions has been the focus of several major field campaigns. However, until recently there have been no measurements aimed at characterizing ice nuclei (IN) in this region. Such measurements are critical for understanding cloud and precipitation processes. In this paper, we present recent ice nuclei measurements from the AMazonian Aerosol characteriZation Experiment 2008 (AMAZE-08). These data were collected during the rainy season at the Instituto Nacional de Pesquisas da Amazonia TT34 tower northeast of Manaus, Brazil. Results are presented for ice nuclei number concentration and elemental composition collected using the Colorado State University Continuous Flow ice thermal Diffusion Chamber (CFDC). The data suggest that, like many regions of the world, IN concentrations are largely controlled by the presence of desert dust, in this case transported from Africa. However, carbonaceous particles also made up a significant fraction of IN. Based on complementary aerosol composition measurements, we consider possible sources of this carbonaceous fraction.

  15. Electron and pion scattering off nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Buss, O.; Mosel, U. [Inst. fuer Theoretische Physik, Univ. Giessen (Germany); Alvarez-Ruso, L. [Dept. de Fisica Teorica and IFIC, Centro Mixto Univ. de Valencia-CSIC (Spain)

    2007-07-01

    We present a treatment of pion and electron scattering off nuclei within the framework of a Boltzmann-Uehling-Uhlenbeck (BUU) transport model. In this approach we realize a full coupled channel treatment and include medium modifications such as mean-field potentials, Fermi motion and width modifications. We have applied the GiBUU model to the description of the double charge exchange (DCX) reaction of pions with different nuclear targets at incident kinetic energies of 120-180 MeV. The DCX process is highly sensitive to details of the interactions of pions with the nuclear medium and, therefore, represents a major benchmark for any model of pion scattering off nuclei at low and intermediate energies. We discuss the impact of surface effects and the dependence on the nuclear mass number. We have achieved a good quantitative agreement with the extensive data set obtained at LAMPF. Furthermore, we present a description of electron induced reactions, i.e. pion production, off nuclei. We consider the scattering of electrons off the bound nucleons in an impulse approximation and investigate medium modifications to exclusive particle production cross sections and compare our results to available data. (orig.)

  16. Adiabatic fission barriers in superheavy nuclei

    CERN Document Server

    Jachimowicz, P; Skalski, J

    2016-01-01

    Using the microscopic-macroscopic model based on the deformed Woods-Saxon single-particle potential and the Yukawa-plus-exponential macroscopic energy we calculated static fission barriers $B_{f}$ for 1305 heavy and superheavy nuclei $98\\leq Z \\leq 126$, including even - even, odd - even, even - odd and odd - odd systems. For odd and odd-odd nuclei, adiabatic potential energy surfaces were calculated by a minimization over configurations with one blocked neutron or/and proton on a level from the 10-th below to the 10-th above the Fermi level. The parameters of the model that have been fixed previously by a fit to masses of even-even heavy nuclei were kept unchanged. A search for saddle points has been performed by the "Imaginary Water Flow" method on a basic five-dimensional deformation grid, including triaxiality. Two auxiliary grids were used for checking the effects of the mass asymmetry and hexadecapole non-axiallity. The ground states were found by energy minimization over configurations and deformations...

  17. Interaction of eta mesons with nuclei

    CERN Document Server

    Kelkar, N G; Upadhyay, N J; Jain, B K

    2013-01-01

    Back in the mid eighties, a new branch of investigation which was related to the interaction of eta mesons with nuclei came into existence. It started with the theoretical prediction of possible exotic states of eta mesons and nuclei bound by the strong interaction and later developed into an extensive experimental program to search for such unstable states as well as understand the underlying interaction via eta meson producing reactions. The vast literature of experimental as well as theoretical works which studied various aspects of eta producing reactions such as the $\\pi ^+$ $n$ $\\to \\eta p$, $p d \\to ^3$He $\\eta$, $p \\,^6$Li $\\to ^7$Be $\\eta$ and $\\gamma ^3$He $\\to \\eta$ X, to name a few, had but one objective in mind: to understand the eta - nucleon ($\\eta N$) and hence the $\\eta$-nucleus interaction which could explain the production data and confirm the existence of some $\\eta$-mesic nuclei. In spite of these efforts, there remain uncertainties in the knowledge of the $\\eta N$ and hence the $\\eta$-nu...

  18. Chromatin associations in Arabidopsis interphase nuclei

    Directory of Open Access Journals (Sweden)

    Veit eSchubert

    2014-11-01

    Full Text Available The arrangement of chromatin within interphase nuclei seems to be caused by topological constraints and related to gene expression depending on tissue and developmental stage. In yeast and animals it was found that homologous and heterologous chromatin association are required to realize faithful expression and DNA repair. To test whether such associations are present in plants we analysed Arabidopsis thaliana interphase nuclei by FISH using probes from different chromosomes. We found that chromatin fibre movement and variable associations, although in general relatively seldom, may occur between euchromatin segments along chromosomes, sometimes even over large distances. The combination of euchromatin segments bearing high or low co-expressing genes did not reveal different association frequencies probably due to adjacent genes of deviating expression patterns.Based on previous data and on FISH analyses presented here, we conclude that the global interphase chromatin organization in A. thaliana is relatively stable, due to the location of its ten centromeres at the nuclear periphery and of the telomeres mainly at the centrally localized nucleolus. Nevertheless, chromatin movement enables a flexible spatial genome arrangement in plant nuclei.

  19. Wave function calculations in finite nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Pieper, S.C.

    1993-07-01

    One of the central problems in nuclear physics is the description of nuclei as systems of nucleons interacting via realistic potentials. There are two main aspects of this problem: (1) specification of the Hamiltonian, and (2) calculation of the ground (or excited) states of nuclei with the given interaction. Realistic interactions must contain both two- and three-nucleon potentials and these potentials have a complicated non-central operator structure consisting, for example, of spin, isospin and tensor dependencies. This structure results in formidable many-body problems in the computation of the ground states of nuclei. At Argonne and Urbana, the authors have been following a program of developing realistic NN and NNN interactions and the methods necessary to compute nuclear properties from variational wave functions suitable for these interactions. The wave functions are used to compute energies, density distributions, charge form factors, structure functions, momentum distributions, etc. Most recently they have set up a collaboration with S. Boffi and M. Raduci (University of Pavia) to compute (e,e{prime}p) reactions.

  20. Wave function calculations in finite nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Pieper, S.C.

    1993-01-01

    One of the central problems in nuclear physics is the description of nuclei as systems of nucleons interacting via realistic potentials. There are two main aspects of this problem: (1) specification of the Hamiltonian, and (2) calculation of the ground (or excited) states of nuclei with the given interaction. Realistic interactions must contain both two- and three-nucleon potentials and these potentials have a complicated non-central operator structure consisting, for example, of spin, isospin and tensor dependencies. This structure results in formidable many-body problems in the computation of the ground states of nuclei. At Argonne and Urbana, the authors have been following a program of developing realistic NN and NNN interactions and the methods necessary to compute nuclear properties from variational wave functions suitable for these interactions. The wave functions are used to compute energies, density distributions, charge form factors, structure functions, momentum distributions, etc. Most recently they have set up a collaboration with S. Boffi and M. Raduci (University of Pavia) to compute (e,e[prime]p) reactions.

  1. Multi-K¯ nuclei and kaon condensation

    Science.gov (United States)

    Gazda, D.; Friedman, E.; Gal, A.; Mareš, J.

    2008-04-01

    We extend previous relativistic mean-field (RMF) calculations of multi-K¯ nuclei, using vector boson fields with SU(3) PPV coupling constants and scalar boson fields constrained phenomenologically. For a given core nucleus, the resulting K¯ separation energy BK¯, as well as the associated nuclear and K¯-meson densities, saturate with the number κ of K¯ mesons for κ>κsat~10. Saturation appears robust against a wide range of variations, including the RMF nuclear model used and the type of boson fields mediating the strong interactions. Because BK¯ generally does not exceed 200 MeV, it is argued that multi-K¯ nuclei do not compete with multihyperonic nuclei in providing the ground state of strange hadronic configurations and that kaon condensation is unlikely to occur in strong-interaction self-bound strange hadronic matter. Last, we explore possibly self-bound strange systems made of neutrons and K¯0 mesons, or protons and K- mesons, and study their properties.

  2. Synthesis of superheavy nuclei with 238U target

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The production of superheavy nuclei with Z=108-116 via hot fusion reactions of the neutron-rich projectiles with 238U target is systematically studied.The results show that the production cross sections of superheavy nuclei do not decrease monotonously as the atomic number Z increasing.The cross sections of the superheavy nuclei at Z = 112 and 115 are enhanced as compared with the whole Z-trend in synthesis of the superheavy nuclei,which clearly illustrates that the reactions with large negative Q-value and shell correction are more favorable to synthesize superheavy nuclei.

  3. Synthesis of superheavy nuclei with 238U target

    Institute of Scientific and Technical Information of China (English)

    LIU ZuHua; BAO JingDong

    2009-01-01

    The production of superheavy nuclei with Z=108-116 via hot fusion reactions of the neutron-rich projectiles with 238u target is systematically studied.The results show that the production cross sections of superheavy nuclei do not decrease monotonously as the atomic number Z increasing.The cross sections of the superheavy nuclei at Z=112 and 115 are enhanced as compared with the whole Z-trend in synthesis of the superheavy nuclei,which clearly illustrates that the reactions with large negative Q-value and shell correction are more favorable to synthesize superheavy nuclei.

  4. Feasibility assessment of vacuum cooling followed by immersion vacuum cooling on water-cooked pork.

    Science.gov (United States)

    Dong, Xiaoguang; Chen, Hui; Liu, Yi; Dai, Ruitong; Li, Xingmin

    2012-01-01

    Vacuum cooling followed by immersion vacuum cooling was designed to cool water-cooked pork (1.5±0.05 kg) compared with air blast cooling (4±0.5°C, 2 m/s), vacuum cooling (10 mbar) and immersion vacuum cooling. This combined cooling method was: vacuum cooling to an intermediate temperature of 25°C and then immersion vacuum cooling with water of 10°C to the final temperature of 10°C. It was found that the cooling loss of this combined cooling method was significantly lower (Pvacuum cooling. This combined cooling was faster (Pvacuum cooling in terms of cooling rate. Moreover, the pork cooled by combined cooling method had significant differences (P<0.05) in water content, color and shear force. Copyright © 2011 Elsevier Ltd. All rights reserved.

  5. Newton's Law of Cooling Revisited

    Science.gov (United States)

    Vollmer, M.

    2009-01-01

    The cooling of objects is often described by a law, attributed to Newton, which states that the temperature difference of a cooling body with respect to the surroundings decreases exponentially with time. Such behaviour has been observed for many laboratory experiments, which led to a wide acceptance of this approach. However, the heat transfer…

  6. Dialogues in the COOL Project

    NARCIS (Netherlands)

    Stalpers, S.I.P.; Kroeze, C.

    2013-01-01

    The Climate Options for the Long-term (COOL) Project is a participatory integrated assessment (PIA) comprising extensive dialogues at three levels: national, European and global. The objective of the COOL Project was to ‘develop strategic notions on how to achieve drastic reductions of greenhouse ga

  7. Be Cool, Man! / Jevgeni Levik

    Index Scriptorium Estoniae

    Levik, Jevgeni

    2005-01-01

    Järg 1995. aasta kriminaalkomöödiale "Tooge jupats" ("Get Shorty") : mängufilm "Be Cool, Chili Palmer on tagasi!" ("Be Cool") : režissöör F. Gary Gray, peaosades J. Travolta ja U. Thurman : USA 2005. Lisatud J. Travolta ja U. Thurmani lühiintervjuud

  8. Temperature initiated passive cooling system

    Science.gov (United States)

    Forsberg, Charles W.

    1994-01-01

    A passive cooling system for cooling an enclosure only when the enclosure temperature exceeds a maximum standby temperature comprises a passive heat transfer loop containing heat transfer fluid having a particular thermodynamic critical point temperature just above the maximum standby temperature. An upper portion of the heat transfer loop is insulated to prevent two phase operation below the maximum standby temperature.

  9. Be Cool, Man! / Jevgeni Levik

    Index Scriptorium Estoniae

    Levik, Jevgeni

    2005-01-01

    Järg 1995. aasta kriminaalkomöödiale "Tooge jupats" ("Get Shorty") : mängufilm "Be Cool, Chili Palmer on tagasi!" ("Be Cool") : režissöör F. Gary Gray, peaosades J. Travolta ja U. Thurman : USA 2005. Lisatud J. Travolta ja U. Thurmani lühiintervjuud

  10. Dew Point Evaporative Comfort Cooling

    Science.gov (United States)

    2012-11-01

    220 Figure 140. Water-cooled chilled water plant with primary/secondary...enough to buffer the space by carrying away solar loads in unoccupied volumes, such as ceiling plenums. For rooftop installations, where ceiling...and are significant for the three-month period and generally exceed 68%. Larger chilled water plants with water-cooled condensers can operate with

  11. Triatomic molecules laser-cooled

    Science.gov (United States)

    2017-06-01

    Molecules containing three atoms have been laser-cooled to ultracold temperatures for the first time. John Doyle and colleagues at Harvard University in the US used a technique called Sisyphus cooling to chill an ensemble of about a million strontium-monohydroxide molecules to 750 μK.

  12. A novel electronic cooling concept

    Science.gov (United States)

    Ponnappan, R.; Beam, J. E.

    Advanced electrical power conditioning systems for the More Electric Aircraft Initiative involve high currents and high voltages with the attendant waste heat generation and cooling problems. The use of solid state switching devices such as MCTs for these systems will result in power dissipation of several hundred Watts per square centimeter. Conventional forced air or low velocity single phase fluid cooling is inadequate to handle the waste heat dissipation of these high power devices. More advanced and innovative methods of cooling which can use fluids available in the aircraft and also easy to package are sought. A new approach called 'venturi flow cooling concept' is described. It is shown that localized cooling up to 200 W/sq cm is possible at the venturi throat region where the MCTs can be mounted. PAO coolant with Pr = 56 at 40 C can be conveniently used in aircraft.

  13. Laser cooling to quantum degeneracy.

    Science.gov (United States)

    Stellmer, Simon; Pasquiou, Benjamin; Grimm, Rudolf; Schreck, Florian

    2013-06-28

    We report on Bose-Einstein condensation in a gas of strontium atoms, using laser cooling as the only cooling mechanism. The condensate is formed within a sample that is continuously Doppler cooled to below 1  μK on a narrow-linewidth transition. The critical phase-space density for condensation is reached in a central region of the sample, in which atoms are rendered transparent for laser cooling photons. The density in this region is enhanced by an additional dipole trap potential. Thermal equilibrium between the gas in this central region and the surrounding laser cooled part of the cloud is established by elastic collisions. Condensates of up to 10(5) atoms can be repeatedly formed on a time scale of 100 ms, with prospects for the generation of a continuous atom laser.

  14. Statistical properties of quantum spectra in nuclei

    Institute of Scientific and Technical Information of China (English)

    WU; Xizhen

    2001-01-01

    [1]Wu Xizhen,Sakata,F.,Zhuo Yizhong et al.,Dynamic realization of statistical state in finite systems,Phys.ReV.C,1996,53:1233-1244.[2]Weidenmüller,H.A.,Statistical theory of nuclear reactions and the Gaussian Othogonal Ensemble,Annals of Physics,1984,158:120-141.[3]Hag,R.U.,Pandey,A.,Bohigas,O.,Fluctuation properties of nuclear energy levels:Do theory and experiment agree? Phys.Rev.Lett.,1982,48:1086-1089.[4]Wu Xizhen,Gu Jianzhong,Iwamoto,A.,Statistical properties of quasiparticle spectra in deformed nuclei,Phys.Rev.C,1999,59:215-220.[5]Garrett,J.D.,Robinson,J.Q.,Foglia,A.J.et al.,Nuclear level repulsion and order vs chaos,Phys.Lett.B,1997,392:24-29.[6]Bohigas,O.,Hag,R.U.,Pandy,A.,Fluctuation properties of nuclear energy levels and widths comparison of theory with experiment,in Nuclear Data for Science and Technology (ed.Bockhoff,K.H.),Dordrecht:Reidel,1983,809-813.[7]Heiss,W.D.,Nazmitdinov,R.G.,Radu,S.,Chaos in axially symmetric potentials with Octupole deformation,Phys.Rev.Lett.,1994,72:2351-2354.[8]Wu Xizhen,Gu Jianzhong,Zhuo Yizhong et al.,Possible understanding of hyperdeformed 144-146Ba nuclei appearing in the spontaneous fission of 252Cf,Phys.Rev.Lett.,1997,79:4542-4545.[9]Ter-Akopian,G.M.,Hamilton,J.H.,Oganessian,Y.T.et al.,New spontaneous fission mode for 252Cf:Indication of hyperdeformed 144,145,146Ba at scission,Phys.Rev.Lett.,1996,77:32-35.[10]Adamian,G.G.,Antonenko,N.V.,Ivanova,S.P.et al.,Problems in description of fusion of heavy nuclei in the two-center shell model approach,Nucl.Phys.A,1999,646:29-52.[11]Hofmann,H.,A quantal transport theory for nuclear collective motion:the metrits of a locally harmonic approximation method,Phys.Rep.,1997,284:139-380.[12]Gu Jianzhong,Wu Xizhen,Zhuo Yizhong,Quantum chaotic motion of a single particle in heavy nuclei,Nucl.Phys.A,1997,625:621-632.[13]Gu Jianzhong,Wu Xizhen,Zhuo Yizhong,The single-particle spectrum and its spacing and curvature distributions in

  15. Electric monopole transitions from low energy excitations in nuclei

    CERN Document Server

    Wood, J L; De Coster, C; Heyde, Kris L G

    1999-01-01

    Electric monopole (E0) properties are studied across the entire nuclear mass surface. Besides an introductory discussion of various model results (shell model, geometric vibrational and rotational models, algebraic models), we point out that many of the largest E0 transition strengths, $\\rho^2$(E0), are associated with shape mixing. We discuss in detail the manifestation of E0 transitions and present extensive data for~: single-closed shell nuclei, vibrational nuclei, well-deformed nuclei, nuclei that exhibit sudden ground-state changes, and nuclei that exhibit shape coexistence and intruder states. We also give attention to light nuclei, odd-A nuclei, and illustrate a suggested relation between $\\rho^2$(E0) and isotopic shifts.

  16. Cooling off with physics

    Energy Technology Data Exchange (ETDEWEB)

    Clarke, Chris [Unilever R and D (United Kingdom)

    2003-08-01

    You might think of ice cream as a delicious treat to be enjoyed on a sunny summer's day. However, to the ice-cream scientists who recently gathered in Thessaloniki in Greece for the 2nd International Ice Cream Symposium, it is a complex composite material. Ice cream consists of three dispersed phases: ice crystals, which have a mean size of 50 microns, air bubbles with a diameter of about 70 microns, and fat droplets with a size of 1 micron. These phases are held together by what is called the matrix - not a sci-fi film, but a viscous solution of sugars, milk proteins and polysaccharides. The microstructure, and hence the texture that you experience when you eat ice cream, is created in a freezing process that has remained fundamentally unchanged since the first ice-cream maker was patented in the 1840s. The ingredients - water, milk protein, fat, sugar, emulsifiers, stabilizers, flavours and a lot of air - are mixed together before being pasteurized and homogenized. They are then pumped into a cylinder that is cooled from the outside with a refrigerant. As the mixture touches the cylinder wall it freezes and forms ice crystals, which are quickly scraped off by a rotating blade. The blade is attached to a beater that disperses the ice crystals into the mixture. At the same time, air is injected and broken down into small bubbles by the shear that the beater generates. As the mixture passes along the cylinder, the number of ice crystals increases and its temperature drops. As a result, the viscosity of the mixture increases, so that more energy input is needed to rotate the beater. This energy is dissipated as heat, and when the ice cream reaches about -6 deg. C the energy input through the beater equals the energy removed as heat by the refrigerant. The process therefore becomes self-limiting and it is not possible to cool the ice cream any further. However, at -6 deg. C the microstructure is unstable. The ice cream therefore has to be removed from the freezer

  17. Simulating the Cooling Flow of Cool-Core Clusters

    CERN Document Server

    Li, Yuan

    2011-01-01

    We carry out high-resolution adaptive mesh refinement simulations of a cool core cluster, resolving the flow from Mpc scales down to pc scales. We do not (yet) include any AGN heating, focusing instead on cooling in order to understand how gas gets to the supermassive black hole (SMBH) at the center of the cluster. We find that, as the gas cools, the cluster develops a very flat temperature profile, undergoing a cooling catastrophe only in the central 10-100 pc of the cluster. Outside of this region, the flow is smooth, with no local cooling instabilities, and naturally produces very little low-temperature gas (below a few keV), in agreement with observations. The gas cooling in the center of the cluster rapidly forms a thin accretion disk. The amount of cold gas produced at the very center grows rapidly until a reasonable estimate of the resulting AGN heating rate (assuming even a moderate accretion efficiency) would overwhelm cooling. We argue that this naturally produces a thermostat which links the coolin...

  18. 46 CFR 153.432 - Cooling systems.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Cooling systems. 153.432 Section 153.432 Shipping COAST... Control Systems § 153.432 Cooling systems. (a) Each cargo cooling system must have an equivalent standby... cooling system. (b) Each tankship that has a cargo tank with a required cooling system must have a manual...

  19. Convective cooling of photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Hodge, E.; Gibbons, C. [Energy Engineering Group, Mechanical Engineering Department, Cork Institute of Technology, Bishopstown, Cork (Ireland)

    2004-07-01

    Most solar cells presently on the market are based on silicon wafers, the so-called first generation technology. As this technology has matured costs have become increasingly dominated by material costs. In the last ten years, continuous work has brought the efficiency of standard cells to the 25% region. A switch to second generation or thin film technology cells now seems imminent. Thin film technology eliminates the silicon wafer and offer the prospect of reducing material and manufacturing costs, but they exhibit lower efficiencies of around 10% for a commercial device. Third generation or tandem cells are currently at a 'proof of concept' research level, with a theoretical conversion rate of 86.8% being asserted Whatever the material construction and manufacturing method of cells, the thermal effect of overheating will prevail in the semiconductor and it is accepted that a lowered temperature will bring about an increase in conversion efficiency. The aim of this project is to improve the efficiency of PV electrical output, by convectively cooling the cells through perforations in them. As the cells heat up they lose efficiency. As the panel heats up a loss in efficiency of 0.5% per C increase in temperature has been recorded. (orig.)

  20. Central cooling: absorptive chillers

    Energy Technology Data Exchange (ETDEWEB)

    Christian, J.E.

    1977-08-01

    This technology evaluation covers commercially available single-effect, lithium-bromide absorption chillers ranging in nominal cooling capacities of 3 to 1,660 tons and double-effect lithium-bromide chillers from 385 to 1,060 tons. The nominal COP measured at operating conditions of 12 psig input steam for the single-effect machine, 85/sup 0/ entering condenser water, and 44/sup 0/F exiting chilled-water, ranges from 0.6 to 0.65. The nominal COP for the double-effect machine varies from 1.0 to 1.15 with 144 psig entering steam. Data are provided to estimate absorption-chiller performance at off-nominal operating conditions. The part-load performance curves along with cost estimating functions help the system design engineer select absorption equipment for a particular application based on life-cycle costs. Several suggestions are offered which may be useful for interfacing an absorption chiller with the remaining Integrated Community Energy System. The ammonia-water absorption chillers are not considered to be readily available technology for ICES application; therefore, performance and cost data on them are not included in this evaluation.

  1. Performance of Air-cooled Engine Cylinders Using Blower Cooling

    Science.gov (United States)

    Schey, Oscar W; Ellerbrock, Herman H , Jr

    1936-01-01

    An investigation was made to obtain information on the minimum quantity of air and power required to cool conventional air cooled cylinders at various operating conditions when using a blower. The results of these tests show that the minimum power required for satisfactory cooling with an overall blower efficiency of 100 percent varied from 2 to 6 percent of the engine power depending on the operating conditions. The shape of the jacket had a large effect on the cylinder temperatures. Increasing the air speed over the front of the cylinder by keeping the greater part of the circumference of the cylinder covered by the jacket reduced the temperatures over the entire cylinder.

  2. The Lx-Tvir relation in galaxy clusters: Effects of radiative cooling and AGN heating

    CERN Document Server

    Mittal, Rupal; Reiprich, Thomas H; Jaritz, Vera

    2011-01-01

    We present a detailed investigation of the X-ray luminosity (Lx)-gas temperature (Tvir) relation of the complete X-ray flux-limited sample of the 64 brightest galaxy clusters in the sky (HIFLUGCS). We study the influence of two astrophysical processes, active galactic nuclei (AGN) heating and intracluster medium (ICM) cooling, on the Lx-Tvir relation, simultaneously for the first time. We determine best-fit relations for different subsamples using the cool-core strength and the presence of central radio activity as selection criteria. We find the strong cool-core clusters (SCCs) with short cooling times ( 7.7Gyr) to display the shallowest (Lx ~ Tvir^{2.42}). This has the simple implication that on the high-mass scale (Tvir > 2.5keV) the steepening of the Lx-Tvir relation is mainly due to the cooling of the intracluster medium gas. We propose that ICM cooling and AGN heating are both important in shaping the Lx-Tvir relation but on different length-scales. While our study indicates that ICM cooling dominates o...

  3. Collisions of Rare Earth Nuclei - a New Reaction Route for Synthesis of Super Heavy Nuclei

    CERN Document Server

    Choudhury, R K

    2012-01-01

    Theories have predicted an island of stability in the super heavy mass region with half lives ranging from a few seconds to a few thousands of years. Extensive efforts are being made experimentally to reach these nuclei in the region of Z = 110 and above with suitable combinations of proton and neutron numbers. However, the cross sections for production of these nuclei are seen to be in the range of a few pico barns or less, and pose great experimental challenges. We show in the present note that great advantages can be obtained by carrying out heavy ion reactions with suitable combinations of projectile and target nuclei in the rare earth region, that will lead to compound systems with very small excitation energy, and with better neutron/proton ratio for larger stability.

  4. From heavy nuclei to super-heavy nuclei; Des noyaux lourds aux super-lourds

    Energy Technology Data Exchange (ETDEWEB)

    Theisen, Ch

    2003-01-01

    The existence of super-heavy nuclei has been predicted nearly fifty years ago. Due to the strong coulomb repulsion, the stabilisation of these nuclei is possible only through shell effects. The reasons for this fragile stability, as well as the theoretical predictions concerning the position of the island of stability are presented in the first part of this lecture. In the second part, experiments and experimental techniques which have been used to synthesize or search for super-heavy elements are described. Spectroscopic studies performed in very heavy elements are presented in the following section. We close this lecture with techniques that are currently being developed in order to reach the superheavy island and to study the structure of very-heavy nuclei. (author)

  5. Recent topics of mesic atoms and mesic nuclei -- $\\phi$ mesic nuclei exist ?--

    CERN Document Server

    Yamagata-Sekihara, J; Cabrera, D; Vacas, M J Vicente

    2008-01-01

    We study $\\phi$-meson production in nuclei to investigate the in-medium modification of the $\\phi$-meson spectral function at finite density. We consider (${\\bar p},\\phi$), ($\\gamma,p$) and ($\\pi^-,n$) reactions to produce a $\\phi$-meson inside the nucleus and evaluate the effects of the medium modifications to reaction cross sections. The structures of the bound states, $\\phi$-mesic nuclei, are also studied. For strong absorptive interaction cases, we need to know the spectrum shape in a wide energy region to deduce the properties of $\\phi$.

  6. Cooling arrangement for a tapered turbine blade

    Science.gov (United States)

    Liang, George

    2010-07-27

    A cooling arrangement (11) for a highly tapered gas turbine blade (10). The cooling arrangement (11) includes a pair of parallel triple-pass serpentine cooling circuits (80,82) formed in an inner radial portion (50) of the blade, and a respective pair of single radial channel cooling circuits (84,86) formed in an outer radial portion (52) of the blade (10), with each single radial channel receiving the cooling fluid discharged from a respective one of the triple-pass serpentine cooling circuit. The cooling arrangement advantageously provides a higher degree of cooling to the most highly stressed radially inner portion of the blade, while providing a lower degree of cooling to the less highly stressed radially outer portion of the blade. The cooling arrangement can be implemented with known casting techniques, thereby facilitating its use on highly tapered, highly twisted Row 4 industrial gas turbine blades that could not be cooled with prior art cooling arrangements.

  7. How AGN feedback and metal cooling shape cluster entropy profiles

    CERN Document Server

    Dubois, Yohan; Teyssier, Romain; Slyz, Adrianne

    2011-01-01

    Observed clusters of galaxies essentially come in two flavors: non cool core clusters characterized by an isothermal temperature profile and a central entropy floor, and cool-core clusters where temperature and entropy in the central region are increasing with radius. Using cosmological resimulations of a galaxy cluster, we study the evolution of its intracluster medium (ICM) gas properties, and through them we assess the effect of different (sub-grid) modelling of the physical processes at play, namely gas cooling, star formation, feedback from supernovae and active galactic nuclei (AGN). More specifically we show that AGN feedback plays a major role in the pre-heating of the proto-cluster as it prevents a high concentration of mass from collecting in the center of the future galaxy cluster at early times. However, AGN activity during the cluster's later evolution is also required to regulate the mass flow into its core and prevent runaway star formation in the central galaxy. Whereas the energy deposited by...

  8. New Approaches to Final Cooling

    CERN Document Server

    Neuffer, David

    2015-01-01

    A high-energy muon collider scenario requires a "final cooling" system that reduces transverse emittance by a factor of ~10 while allowing longitudinal emittance increase. The baseline approach has low-energy transverse cooling within high-field solenoids, with strong longitudinal heating. This approach and its recent simulation are discussed. Alternative approaches which more explicitly include emittance exchange are also presented. Round-to-flat beam transform, transverse slicing, and longitudinal bunch coalescence are possible components of the alternative approach. A more explicit understanding of solenoidal cooling beam dynamics is introduced.

  9. Cooling towers principles and practice

    CERN Document Server

    Hill, G B; Osborn, Peter D

    1990-01-01

    Cooling Towers: Principles and Practice, Third Edition, aims to provide the reader with a better understanding of the theory and practice, so that installations are correctly designed and operated. As with all branches of engineering, new technology calls for a level of technical knowledge which becomes progressively higher; this new edition seeks to ensure that the principles and practice of cooling towers are set against a background of up-to-date technology. The book is organized into three sections. Section A on cooling tower practice covers topics such as the design and operation of c

  10. CLIC inner detectors cooling simulations

    CERN Document Server

    Duarte Ramos, F.; Villarejo Bermudez, M.

    2014-01-01

    The strict requirements in terms of material budget for the inner region of the CLIC detector concepts require the use of a dry gas for the cooling of the respective sen- sors. This, in conjunction with the compactness of the inner volumes, poses several challenges for the design of a cooling system that is able to fulfil the required detec- tor specifications. This note introduces a detector cooling strategy using dry air as a coolant and shows the results of computational fluid dynamics simulations used to validate the proposed strategy.

  11. Effective field theory description of halo nuclei

    Science.gov (United States)

    Hammer, H.-W.; Ji, C.; Phillips, D. R.

    2017-10-01

    Nuclear halos emerge as new degrees of freedom near the neutron and proton driplines. They consist of a core and one or a few nucleons which spend most of their time in the classically-forbidden region outside the range of the interaction. Individual nucleons inside the core are thus unresolved in the halo configuration, and the low-energy effective interactions are short-range forces between the core and the valence nucleons. Similar phenomena occur in clusters of 4He atoms, cold atomic gases near a Feshbach resonance, and some exotic hadrons. In these weakly-bound quantum systems universal scaling laws for s-wave binding emerge that are independent of the details of the interaction. Effective field theory (EFT) exposes these correlations and permits the calculation of non-universal corrections to them due to short-distance effects, as well as the extension of these ideas to systems involving the Coulomb interaction and/or binding in higher angular-momentum channels. Halo nuclei exhibit all these features. Halo EFT, the EFT for halo nuclei, has been used to compute the properties of single-neutron, two-neutron, and single-proton halos of s-wave and p-wave type. This review summarizes these results for halo binding energies, radii, Coulomb dissociation, and radiative capture, as well as the connection of these properties to scattering parameters, thereby elucidating the universal correlations between all these observables. We also discuss how Halo EFT's encoding of the long-distance physics of halo nuclei can be used to check and extend ab initio calculations that include detailed modeling of their short-distance dynamics.

  12. Nuclei at extreme conditions. A relativistic study

    Energy Technology Data Exchange (ETDEWEB)

    Afanasjev, Anatoli [Mississippi State Univ., Mississippi State, MS (United States)

    2014-11-14

    The major goals of the current project were further development of covariant density functional theory (CDFT), better understanding of its features, its application to different nuclear structure and nuclear astrophysics phenomena and training of graduate and undergraduate students. The investigations have proceeded in a number of directions which are discussed in detail in the part “Accomplishments” of this report. We have studied the role of isovector and isoscalar proton-neutron pairings in rotating nuclei; based on available experimental data it was concluded that there are no evidences for the existence of isoscalar proton-neutron pairing. Generalized theoretical approach has been developed for pycnonuclear reaction rates in the crust of neutron stars and interior of white dwarfs. Using this approach, extensive database for considerable number of pycnonuclear reactions involving stable and neutron-rich light nuclei has been created; it can be used in future for the study of various nuclear burning phenomena in different environments. Time-odd mean fields and their manifestations in terminating states, non-rotating and rotating nuclei have been studied in the framework of covariant density functional theory. Contrary to non-relativistic density functional theories these fields, which are important for a proper description of nuclear systems with broken time-reversal symmetry, are uniquely defined in the CDFT framework. Hyperdeformed nuclear shapes (with semi-axis ratio 2.5:1 and larger) have been studied in the Z = 40-58 part of nuclear chart. We strongly believe that such shapes could be studied experimentally in the future with full scale GRETA detector.

  13. Passive low energy cooling of buildings

    CERN Document Server

    Givoni, Baruch

    1994-01-01

    A practical sourcebook for building designers, providing comprehensive discussion of the impact of basic architectural choices on cooling efficiency, including the layout and orientation of the structure, window size and shading, exterior color, and even the use of plantings around the site. All major varieties of passive cooling systems are presented, with extensive analysis of performance in different types of buildings and in different climates: ventilation; radiant cooling; evaporative cooling; soil cooling; and cooling of outdoor spaces.

  14. Modello per una sistematica dei nuclei stabili

    Directory of Open Access Journals (Sweden)

    Medi Enrico

    1960-06-01

    Full Text Available Mediante una espressione lineare e tre successioni di numeri semplici
    è possibile ricostruire, nella quasi totalità, la serie dei nuclei degli elementi
    stabili. È cioè possibile conoscere il numero dei protoni (e quindi dei
    neutroni che entrano a far parte del nucleo di un elemento stabile,
    quando sia dato il numero di massa di esso.
    Il metodo è dedotto da un modello di nucleo a particelle alfa, secondo
    uno schema di simmetria di tipo cristallino, inteso ovviamente
    in senso topologico.

  15. Effective field theory for deformed atomic nuclei

    Science.gov (United States)

    Papenbrock, T.; Weidenmüller, H. A.

    2016-05-01

    We present an effective field theory (EFT) for a model-independent description of deformed atomic nuclei. In leading order this approach recovers the well-known results from the collective model by Bohr and Mottelson. When higher-order corrections are computed, the EFT accounts for finer details such as the variation of the moment of inertia with the band head and the small magnitudes of interband E2 transitions. For rotational bands with a finite spin of the band head, the EFT is equivalent to the theory of a charged particle on the sphere subject to a magnetic monopole field.

  16. Probing Chiral Interactions in Light Nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Nogga, A; Barrett, B R; Meissner, U; Witala, H; Epelbaum, E; Kamada, H; Navratil, P; Glockle, W; Vary, J P

    2004-01-08

    Chiral two- and three-nucleon interactions are studied in a few-nucleon systems. We investigate the cut-off dependence and convergence with respect to the chiral expansion. It is pointed out that the spectra of light nuclei are sensitive to the three-nucleon force structure. As an example, we present calculations of the 1{sup +} and 3{sup +} states of {sup 6}Li using the no-core shell model approach. The results show contributions of the next-to-next-to-leading order terms to the spectra, which are not correlated to the three-nucleon binding energy prediction.

  17. Algebraic description of intrinsic modes in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Leviatan, A. (Los Alamos National Lab., NM (USA))

    1990-01-01

    We present a procedure for extracting normal modes in algebraic number-conserving systems of interacting bosons relevant for collective states in even-even nuclei. The Hamiltonian is resolved into intrinsic (bandhead related) and collective (in-band related) parts. Shape parameters are introduced through non-spherical boson bases. Intrinsic modes decoupled from the spurious modes are obtained from the intrinsic part of the Hamiltonian in the limit of large number of bosons. Intrinsic states are constructed and serve to evaluate electromagnetic transition rates. The method is illustrated for systems with one type of boson as well as with proton-neutron bosons. (author).

  18. Algebraic description of intrinsic modes in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Leviatan, A.

    1989-01-01

    We present a procedure for extracting normal modes in algebraic number-conserving systems of interacting bosons relevant for collective states in even-even nuclei. The Hamiltonian is resolved into intrinsic (bandhead related) and collective (in-band related) parts. Shape parameters are introduced through non-spherical boson bases. Intrinsic modes decoupled from the spurious modes are obtained from the intinsic part of the Hamiltonian in the limit of large number of bosons. Intrinsic states are constructed and serve to evaluate electromagnetic transition rates. The method is illustrated for systems with one type of boson as well as with proton-neutron bosons. 28 refs., 1 fig.

  19. Experimental level densities of atomic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Guttormsen, M.; Bello Garrote, F.L.; Eriksen, T.K.; Giacoppo, F.; Goergen, A.; Hagen, T.W.; Klintefjord, M.; Larsen, A.C.; Nyhus, H.T.; Renstroem, T.; Rose, S.J.; Sahin, E.; Siem, S.; Tornyi, T.G.; Tveten, G.M. [University of Oslo, Department of Physics, Oslo (Norway); Aiche, M.; Ducasse, Q.; Jurado, B. [University of Bordeaux, CENBG, CNRS/IN2P3, B.P. 120, Gradignan (France); Bernstein, L.A.; Bleuel, D.L. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Byun, Y.; Voinov, A. [Ohio University, Department of Physics and Astronomy, Athens, Ohio (United States); Gunsing, F. [CEA Saclay, DSM/Irfu/SPhN, Cedex (France); Lebois, L.; Leniau, B.; Wilson, J. [Institut de Physique Nucleaire d' Orsay, Orsay Cedex (France); Wiedeking, M. [iThemba LABS, P.O. Box 722, Somerset West (South Africa)

    2015-12-15

    It is almost 80 years since Hans Bethe described the level density as a non-interacting gas of protons and neutrons. In all these years, experimental data were interpreted within this picture of a fermionic gas. However, the renewed interest of measuring level density using various techniques calls for a revision of this description. In particular, the wealth of nuclear level densities measured with the Oslo method favors the constant-temperature level density over the Fermi-gas picture. From the basis of experimental data, we demonstrate that nuclei exhibit a constant-temperature level density behavior for all mass regions and at least up to the neutron threshold. (orig.)

  20. Fusion and reactions of exotic nuclei

    Directory of Open Access Journals (Sweden)

    Sánchez-Benítez A.M.

    2011-10-01

    Full Text Available Close to the drip lines, the scattering cross sections of halo nuclei show a different behaviour as compared to the tightly bound projectiles of the stability line. Several experiments carried out in the last decade have been dedicated to investigate the competition between transfer, breakup and fusion channels at energies around and below the Coulomb barrier. The rather complex scenario gives rise to conflicting conclusions concerning the effect of breakup and transfer on reaction dynamics and the sub-barrier fusion process. In this work we discuss recent experimental findings in fusion and reactions of 6He halo nucleus at energies around the Coulomb barrier.

  1. Effective field theory for deformed atomic nuclei

    CERN Document Server

    Papenbrock, T

    2015-01-01

    We present an effective field theory (EFT) for a model-independent description of deformed atomic nuclei. In leading order this approach recovers the well-known results from the collective model by Bohr and Mottelson. When higher-order corrections are computed, the EFT accounts for finer details such as the variation of the moment of inertia with the band head and the small magnitudes of interband $E2$ transitions. For rotational bands with a finite spin of the band head, the EFT is equivalent to the theory of a charged particle on the sphere subject to a magnetic monopole field.

  2. Short-Distance Structure of Nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Douglas Higinbotham, Eliazer Piasetzky, Stephen Wood

    2011-06-01

    One of Jefferson Lab's original missions was to further our understanding of the short-distance structure of nuclei. In particular, to understand what happens when two or more nucleons within a nucleus have strongly overlapping wave-functions; a phenomena commonly referred to as short-range correlations. Herein, we review the results of the (e,e'), (e,e'p) and (e,e'pN) reactions that have been used at Jefferson Lab to probe this short-distance structure as well as provide an outlook for future experiments.

  3. Coherent Pions From Neutrino Scattering Off Nuclei

    CERN Document Server

    Valverde, M; Hernandez, E; Nieves, J; Vacas, M J Vicente

    2010-01-01

    We describe a model for pion production off nucleons and coherent pions from nuclei induced by neutrinos in the 1 GeV energy regime. Besides the dominant Delta pole contribution, it takes into account the effect of background terms required by chiral symmetry. Moreover, the model uses a reduced nucleon-to-Delta resonance axial coupling, which leads to coherent pion production cross sections around a factor two smaller than most of the previous theoretical estimates. Nuclear effects like medium corrections on the Delta propagator and final pion distortion are included.

  4. Inclusive inelastic electron scattering from nuclei

    CERN Document Server

    Fomin, Nadia

    2007-01-01

    Inclusive electron scattering from nuclei at large x and $Q^2$ is the result of a reaction mechanism that includes both quasi--elastic scattering from nucleons and deep inelastic scattering from the quark constituents of the nucleons. Data in this regime can be used to study a wide variety of topics, including the extraction of nuclear momentum distributions, the influence of final state interactions and the approach to $y$-scaling, the strength of nucleon-nucleon correlations, and the approach to $x$- scaling, to name a few. Selected results from the recent experiment E02-019 at the Thomas Jefferson National Accelerator Facility will be shown and their relevance discussed.

  5. Superheavy nuclei – cold synthesis and structure

    Indian Academy of Sciences (India)

    Raj K Gupta

    2001-08-01

    The quantum mechanical fragmentation theory (QMFT), given for the cold synthesis of new and superheavy elements, is reviewed and the use of radioactive nuclear beams (RNB) and targets (RNT) is discussed. The QMFT is a complete theory of cold nuclear phenomena, namely, the cold fission, cold fusion and cluster radioactivity. Also, the structure calculations based on the axially deformed relativistic mean field (DRMF) approach are presented which predict new regions of spherical magicity, namely = 120 and = 172 or 184, for superheavy nuclei. This result is discussed in the light of recent experiments reporting the cold synthesis of = 118 element.

  6. Cosmic rays from active galactic nuclei

    CERN Document Server

    Berezhko, E G

    2008-01-01

    Cosmic ray (CR) acceleration at the shock created by the expanding cocoons around active galactic nuclei (AGNs) is studied. It is shown that above the energy $10^{18}$ eV the overall energy spectrum of CRs, produced during the AGN evolution and released in the intergalactic space, has the form $N\\propto \\epsilon^{-\\gamma}$, with $\\gamma\\approx 2.6$, which extends up to $\\epsilon_{max}\\sim 10^{20}$ eV. It is concluded that cocoons shocks have to be considered as a main source of extragalactic CRs, which together with Galactic supernova remnants provide the observed CR spectrum.

  7. Incoherent rho^0 electroproduction off nuclei

    CERN Document Server

    Falter, T; Mosel, U

    2003-01-01

    In the present paper we investigate incoherent rho^0 electroproduction off complex nuclei. We derive a novel, simple expression for the incoherent electroproduction cross section in which one can clearly separate the final state interactions of the reaction products from the 'initial state interactions' of the photon that give rise to nuclear shadowing. In the special case of purely absorptive final state interactions we deduce from our expression the known Glauber result. A more realistic treatment of the final state interactions within a transport model is then used to compare our predictions with experimental data from the HERMES experiment.

  8. Double giant dipole resonance in hot nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Cinausero, M.; Rizzi, V.; Viesti, G.; Fabris, D.; Lunardon, M.; Moretto, S.; Nebbia, G.; Pesente, S.; Barbui, M.; Fioretto, E.; Prete, G.; Bracco, A.; Camera, F.; Million, B.; Leoni, S.; Wieland, O.; Benzoni, G.; Brambilla, S.; Airoldi, A.; Maj, A.; Kmiecik, M

    2004-02-09

    Signals from Double Dipole Giant Resonances (DGDR) in hot nuclei have been searched in a {gamma}-{gamma} coincidence experiment using the HECTOR array at the Laboratori Nazionali di Legnaro. The experimental single {gamma}-ray spectrum and the projection of the {gamma}-{gamma} matrix have been compared with a standard Monte Carlo Statistical Model code including only the single GDR excitation. These calculations have been used as background to determine the extra-yield associated with the DGDR de-excitation. Results have been compared with a previous experiment confirming the presence of the DGDR excitation in fusion-evaporation reactions.

  9. Few-body resonances in light nuclei

    CERN Document Server

    Csoto, A

    2000-01-01

    We have localized several few-body resonances in light nuclei, using methods which can properly handle two- or three-body resonant states. Among other results, we predict the existence of a three-neutron resonance, small spin-orbit splittings between the low-lying states in He-5 and Li-5, the nonexistence of the soft dipole resonance in He-6, new 1+ states in Li-8 and B-8, and the presence of a nonlinear amplification phenomenon in the 0+_2 state of C-12.

  10. Signatures for quark clustering in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, C.E. [College of William and Mary, Williamsburg, VA (United States); Lassila, K.E. [Iowa State Univ., Ames, IA (United States)

    1994-04-01

    As a signature for the presence of quark clusters in nuclei, the authors suggest studying backward protons produced by electron scattering off deuterons and suggest a ratio that cancels out much of the detailed properties of deuterons or 6-quark clusters. The test may be viewed as a test that the short range part of the deuteron is still a 2-nucleon system. They make estimates to show how it fails in characteristic and significant ways if the two nucleons at short range coalesce into a kneaded 6-quark cluster.

  11. The Structure of Nuclei Far from Stability

    Energy Technology Data Exchange (ETDEWEB)

    Zganjar, E.F.

    1999-02-25

    From among a number of important nuclear structure results that have emerged from our research program during the past few years, two stand out as being of extra significance. These are: (a) the identification of a diabatic coexisting structure in {sup 187}Au which arises solely from differences in proton occupation of adjacent oscillator shells, and (b) the realization of a method for estimating EO strength in nuclei and the resulting prediction that the de-excitation of superdeformed bands may proceed, in some cases, by strong EO transitions.

  12. Reactions and structure of exotic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Esbensen, H.

    1993-08-01

    Radioactive beam experiments have made it possible to study the structure of light neutron rich nuclei. A characteristic feature is a large dipole strength near threshold. An excellent example is the loosely bound nucleus ``Li for which Coulomb dissociation plays a dominant role in breakup reactions on a high Z target. I will describe a three-body model and apply it to calculate the dipole response of {sup 11}Li and the momentum distributions for the three-body breakup reaction: {sup 11}Li {yields} {sup 9}Li+n+n, and comparisons will be made to recent three-body coincidence measurements.

  13. Photofissility of heavy nuclei at intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Deppman, A.; Arruda Neto, J.D.T.; Likhachev, V.P. [Sao Paulo Univ., SP (Brazil). Inst. de Fisica; Tavares, O.A.P.; Duarte, S.B.; Oliveira, E.C. de [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Goncalves, M. [Instituto de Radioprotecao e Dosimetria (IRD), Rio de Janeiro, RJ (Brazil)

    2002-10-01

    We use the recently developed MCMC/MCEF (Multi Collisional Monte Carlo plus Monte Carlo for Evaporation-Fission calculations) model to calculate the photo fissility and the photofission cross section at intermediate energies for the {sup 243} Am and for {sup 209} Bi, and compare them to results obtained for other actinides and to available experimental data. As expected, the results for {sup 243} Am are close to those for {sup 237} Np. The fissility for pre actinide nuclei is nearly one order of magnitude lower than that for the actinides. Both fissility and photofission cross section for {sup 209} Bi are in good agreement with the experimental data. (author)

  14. Modeling a neutron rich nuclei source

    Energy Technology Data Exchange (ETDEWEB)

    Mirea, M.; Bajeat, O.; Clapier, F.; Ibrahim, F.; Mueller, A.C.; Pauwels, N.; Proust, J. [Institut de Physique Nucleaire, IN2P3/CNRS, 91 - Orsay (France); Mirea, M. [Institute of Physics and Nuclear Engineering, Tandem Lab., Bucharest (Romania)

    2000-07-01

    The deuteron break-up process in a suitable converter gives rise to intense neutron beams. A source of neutron rich nuclei based on the neutron induced fission can be realised using these beams. A theoretical optimization of such a facility as a function of the incident deuteron energy is reported. The model used to determine the fission products takes into account the excitation energy of the target nucleus and the evaporation of prompt neutrons. Results are presented in connection with a converter-target specific geometry. (author000.

  15. Experimental level densities of atomic nuclei

    CERN Document Server

    Guttormsen, M; Garrote, F L Bello; Bernstein, L A; Bleuel, D L; Byun, Y; Ducasse, Q; Eriksen, T K; Giacoppo, F; Görgen, A; Gunsing, F; Hagen, T W; Jurado, B; Klintefjord, M; Larsen, A C; Lebois, L; Leniau, B; Nyhus, H T; Renstrøm, T; Rose, S J; Sahin, E; Siem, S; Tornyi, T G; Tveten, G M; Voinov, A; Wiedeking, M; Wilson, J

    2015-01-01

    It is almost 80 years since Hans Bethe described the level density as a non-interacting gas of protons and neutrons. In all these years, experimental data were interpreted within this picture of a fermionic gas. However, the renewed interest of measuring level density using various techniques calls for a revision of this description. In particular, the wealth of nuclear level densities measured with the Oslo method favors the constant-temperature level density over the Fermi-gas picture. From the basis of experimental data, we demonstrate that nuclei exhibit a constant-temperature level density behavior for all mass regions and at least up to the neutron threshold.

  16. Rotational spacings in superdeformed bands of nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Chasman, R.R.; Farhan, A.

    1995-08-01

    An unexpected result of the experimental investigation of superdeformed rotational bands is the observation of near-identical dynamic moments of inertia in different nuclei. This phenomenon was also noted in normally deformed rotational bands. A priori, the BCS method is suspect at I = 0 for the treatment of superdeformed nuclear shapes because the single-particle level density near the nuclear surface is small. If it were large, there would be no superdeformed minimum. At high spin, pairing correlations are further weakened, and the BCS method becomes even worse.

  17. New insights on pseudospin doublets in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Desplanques, B. [Universite Joseph Fourier Grenoble 1, CNRS/IN2P3, INPG, LPSC, Grenoble Cedex (France); Marcos, S. [Universidad de Cantabria, Departamento de Fisica Moderna, Santander (Spain)

    2010-03-15

    The relevance of pseudospin symmetry in nuclei is considered. New insights are obtained from looking at the continuous transition from a non-relativistic model satisfying spin symmetry to another one satisfying pseudospin symmetry. This study suggests that there are models allowing no missing single-particle states in this transition, contrary to what is usually advocated. It rather points to an association of pseudospin partners that is quite different from the one generally assumed, together with a strong violation of the corresponding symmetry. This assignment is supported by an examination of the wave functions and related quantities for the pseudospin partners. (orig.)

  18. Effects of cooling rate and B content on microstructure of near-eutectic Al-13wt%Si Alloy

    Institute of Scientific and Technical Information of China (English)

    Xi Xiao; Zhou Jianyuan; Lü Jianhua

    2008-01-01

    Under cooling rates of 2℃/s and 10℃/s.the Influences of B content on the microstructure of near eutectic Al-13.0wt%Si alloy have been investigated.Results showed that the addition of boron resulted in refinement of eutectic grains,and to some extent,had an inhibiting effect on precipitation of the primary phases,and the refining and inhibiting effects are much more obvious at higher cooling rate.When B was not added,higher cooling rate promoted the α-Al dendrites formation.At Iower cooling rate,the addition of B did not cause the so called"columnar to equiaxed transition(CET)",however,at higher cooling rate,this transition was obvious.After the addition of B,the nucleation temperature TN ascended and nucleation mode changed from nucleation mode of from wall towards centre(without B addition)to a nucleation mode that the eutectic nucleated evenly throughout whole sample (with B added).It can be concluded that the addition of B offers a Iarge amount of nuclei for eutectic solidification,as a result,the eutectic grains was refined.Higher cooling rate will lead to more nuclei,so the effects on the refinement of eutectic grains and on suppression of primary phases are increased.

  19. Cool Cluster Correctly Correlated

    Energy Technology Data Exchange (ETDEWEB)

    Varganov, Sergey Aleksandrovich [Iowa State Univ., Ames, IA (United States)

    2005-01-01

    to tens of atoms. Therefore, they are quantum objects. Some qualitative information about the geometries of such clusters can be obtained with classical empirical methods, for example geometry optimization using an empirical Lennard-Jones potential. However, to predict their accurate geometries and other physical and chemical properties it is necessary to solve a Schroedinger equation. If one is not interested in dynamics of clusters it is enough to solve the stationary (time-independent) Schroedinger equation (HΦ=EΦ). This equation represents a multidimensional eigenvalue problem. The solution of the Schroedinger equation is a set of eigenvectors (wave functions) and their eigenvalues (energies). The lowest energy solution (wave function) corresponds to the ground state of the cluster. The other solutions correspond to excited states. The wave function gives all information about the quantum state of the cluster and can be used to calculate different physical and chemical properties, such as photoelectron, X-ray, NMR, EPR spectra, dipole moment, polarizability etc. The dimensionality of the Schroedinger equation is determined by the number of particles (nuclei and electrons) in the cluster. The analytic solution is only known for a two particle problem. In order to solve the equation for clusters of interest it is necessary to make a number of approximations and use numerical methods.

  20. Compressor bleed cooling fluid feed system

    Science.gov (United States)

    Donahoo, Eric E; Ross, Christopher W

    2014-11-25

    A compressor bleed cooling fluid feed system for a turbine engine for directing cooling fluids from a compressor to a turbine airfoil cooling system to supply cooling fluids to one or more airfoils of a rotor assembly is disclosed. The compressor bleed cooling fluid feed system may enable cooling fluids to be exhausted from a compressor exhaust plenum through a downstream compressor bleed collection chamber and into the turbine airfoil cooling system. As such, the suction created in the compressor exhaust plenum mitigates boundary layer growth along the inner surface while providing flow of cooling fluids to the turbine airfoils.

  1. Cooling Technology for Electronic Computers

    Science.gov (United States)

    Nakayama, Wataru

    The rapid growth of data processing speed in computers has been sustained by the advances in cooling technology. This article first presents a review of the published data of heat loads in recent Japanese large-scale computers. The survey indicates that, since around 1980, the high-level integration of microelectronic circuits has brought about almost four fold increase in the power dissipation from logic chips. The integration also has invited the evolutions of multichip modules and new schemes of electronic interconnections. Forced convection air-cooling and liquid cooling coupled with thermal connectors are discussed with reference to the designs employed in actual computers. More advanced cooling schemes are also discussed. Finally, the importance of thermal environmental control of computer rooms is emphasized.

  2. Cooled Ceramic Turbine Vane Project

    Data.gov (United States)

    National Aeronautics and Space Administration — N&R Engineering will investigate the feasibility of cooled ceramics, such as ceramic matrix composite (CMC) turbine blade concepts that can decrease specific...

  3. Surface-induced evaporative cooling

    Institute of Scientific and Technical Information of China (English)

    Ke Min; Yan Bo; Cheng Feng; Wang Yu-Zhu

    2009-01-01

    The effects of surface-induced evaporative cooling on an atom chip are investigated. The evolutions of temperature, number and phase-space density of the atom cloud are measured when the atom cloud is brought close to the surface. Rapid decrease of the temperature and number of the atoms is found when the atom-surface distance is < 100 μm. A gain of about a factor of five on the phase-space density is obtained. It is found that the efficiency of the surface-induced evaporative cooling depends on the atom-surface distance and the shape of the evaporative trap. When the atoms are moved very close to the surface, severe heating is observed, which dominates when the holding time is > 8 ms. It is important that the surface-induced evaporative cooling offers novel possibilities for the realization of a continuous condensation, where a spatially varying evaporative cooling is required.

  4. Precision measurement of the mass difference between light nuclei and anti-nuclei

    CERN Document Server

    Adam, Jaroslav; Aggarwal, Madan Mohan; Aglieri Rinella, Gianluca; Agnello, Michelangelo; Agrawal, Neelima; Ahammed, Zubayer; Ahmed, Ijaz; Ahn, Sang Un; Aimo, Ilaria; Aiola, Salvatore; Ajaz, Muhammad; Akindinov, Alexander; Alam, Sk Noor; Aleksandrov, Dmitry; Alessandro, Bruno; Alexandre, Didier; Alfaro Molina, Jose Ruben; Alici, Andrea; Alkin, Anton; Alme, Johan; Alt, Torsten; Altinpinar, Sedat; Altsybeev, Igor; Alves Garcia Prado, Caio; Andrei, Cristian; Andronic, Anton; Anguelov, Venelin; Anielski, Jonas; Anticic, Tome; Antinori, Federico; Antonioli, Pietro; Aphecetche, Laurent Bernard; Appelshaeuser, Harald; Arcelli, Silvia; Armesto Perez, Nestor; Arnaldi, Roberta; Aronsson, Tomas; Arsene, Ionut Cristian; Arslandok, Mesut; Augustinus, Andre; Averbeck, Ralf Peter; Azmi, Mohd Danish; Bach, Matthias Jakob; Badala, Angela; Baek, Yong Wook; Bagnasco, Stefano; Bailhache, Raphaelle Marie; Bala, Renu; Baldisseri, Alberto; Ball, Markus; Baltasar Dos Santos Pedrosa, Fernando; Baral, Rama Chandra; Barbano, Anastasia Maria; Barbera, Roberto; Barile, Francesco; Barnafoldi, Gergely Gabor; Barnby, Lee Stuart; Ramillien Barret, Valerie; Bartalini, Paolo; Bartke, Jerzy Gustaw; Bartsch, Esther; Basile, Maurizio; Bastid, Nicole; Basu, Sumit; Bathen, Bastian; Batigne, Guillaume; Batista Camejo, Arianna; Batyunya, Boris; Batzing, Paul Christoph; Bearden, Ian Gardner; Beck, Hans; Bedda, Cristina; Behera, Nirbhay Kumar; Belikov, Iouri; Bellini, Francesca; Bello Martinez, Hector; Bellwied, Rene; Belmont Iii, Ronald John; Belmont Moreno, Ernesto; Belyaev, Vladimir; Bencedi, Gyula; Beole, Stefania; Berceanu, Ionela; Bercuci, Alexandru; Berdnikov, Yaroslav; Berenyi, Daniel; Bertens, Redmer Alexander; Berzano, Dario; Betev, Latchezar; Bhasin, Anju; Bhat, Inayat Rasool; Bhati, Ashok Kumar; Bhattacharjee, Buddhadeb; Bhom, Jihyun; Bianchi, Livio; Bianchi, Nicola; Bianchin, Chiara; Bielcik, Jaroslav; Bielcikova, Jana; Bilandzic, Ante; Biswas, Saikat; Bjelogrlic, Sandro; Blanco, Fernando; Blau, Dmitry; Blume, Christoph; Bock, Friederike; Bogdanov, Alexey; Boggild, Hans; Boldizsar, Laszlo; Bombara, Marek; Book, Julian Heinz; Borel, Herve; Borissov, Alexander; Borri, Marcello; Bossu, Francesco; Botje, Michiel; Botta, Elena; Boettger, Stefan; Braun-Munzinger, Peter; Bregant, Marco; Breitner, Timo Gunther; Broker, Theo Alexander; Browning, Tyler Allen; Broz, Michal; Brucken, Erik Jens; Bruna, Elena; Bruno, Giuseppe Eugenio; Budnikov, Dmitry; Buesching, Henner; Bufalino, Stefania; Buncic, Predrag; Busch, Oliver; Buthelezi, Edith Zinhle; Buxton, Jesse Thomas; Caffarri, Davide; Cai, Xu; Caines, Helen Louise; Calero Diaz, Liliet; Caliva, Alberto; Calvo Villar, Ernesto; Camerini, Paolo; Carena, Francesco; Carena, Wisla; Castillo Castellanos, Javier Ernesto; Castro, Andrew John; Casula, Ester Anna Rita; Cavicchioli, Costanza; Ceballos Sanchez, Cesar; Cepila, Jan; Cerello, Piergiorgio; Chang, Beomsu; Chapeland, Sylvain; Chartier, Marielle; Charvet, Jean-Luc Fernand; Chattopadhyay, Subhasis; Chattopadhyay, Sukalyan; Chelnokov, Volodymyr; Cherney, Michael Gerard; Cheshkov, Cvetan Valeriev; Cheynis, Brigitte; Chibante Barroso, Vasco Miguel; Dobrigkeit Chinellato, David; Chochula, Peter; Choi, Kyungeon; Chojnacki, Marek; Choudhury, Subikash; Christakoglou, Panagiotis; Christensen, Christian Holm; Christiansen, Peter; Chujo, Tatsuya; Chung, Suh-Urk; Cicalo, Corrado; Cifarelli, Luisa; Cindolo, Federico; Cleymans, Jean Willy Andre; Colamaria, Fabio Filippo; Colella, Domenico; Collu, Alberto; Colocci, Manuel; Conesa Balbastre, Gustavo; Conesa Del Valle, Zaida; Connors, Megan Elizabeth; Contreras Nuno, Jesus Guillermo; Cormier, Thomas Michael; Corrales Morales, Yasser; Cortes Maldonado, Ismael; Cortese, Pietro; Cosentino, Mauro Rogerio; Costa, Filippo; Crochet, Philippe; Cruz Albino, Rigoberto; Cuautle Flores, Eleazar; Cunqueiro Mendez, Leticia; Dahms, Torsten; Dainese, Andrea; Danu, Andrea; Das, Debasish; Das, Indranil; Das, Supriya; Dash, Ajay Kumar; Dash, Sadhana; De, Sudipan; De Caro, Annalisa; De Cataldo, Giacinto; De Cuveland, Jan; De Falco, Alessandro; De Gruttola, Daniele; De Marco, Nora; De Pasquale, Salvatore; Deisting, Alexander; Deloff, Andrzej; Denes, Ervin Sandor; D'Erasmo, Ginevra; Di Bari, Domenico; Di Mauro, Antonio; Di Nezza, Pasquale; Diaz Corchero, Miguel Angel; Dietel, Thomas; Dillenseger, Pascal; Divia, Roberto; Djuvsland, Oeystein; Dobrin, Alexandru Florin; Dobrowolski, Tadeusz Antoni; Domenicis Gimenez, Diogenes; Donigus, Benjamin; Dordic, Olja; Dubey, Anand Kumar; Dubla, Andrea; Ducroux, Laurent; Dupieux, Pascal; Ehlers Iii, Raymond James; Elia, Domenico; Engel, Heiko; Erazmus, Barbara Ewa; Erhardt, Filip; Eschweiler, Dominic; Espagnon, Bruno; Estienne, Magali Danielle; Esumi, Shinichi; Evans, David; Evdokimov, Sergey; Eyyubova, Gyulnara; Fabbietti, Laura; Fabris, Daniela; Faivre, Julien; Fantoni, Alessandra; Fasel, Markus; Feldkamp, Linus; Felea, Daniel; Feliciello, Alessandro; Feofilov, Grigorii; Ferencei, Jozef; Fernandez Tellez, Arturo; Gonzalez Ferreiro, Elena; Ferretti, Alessandro; Festanti, Andrea; Figiel, Jan; Araujo Silva Figueredo, Marcel; Filchagin, Sergey; Finogeev, Dmitry; Fionda, Fiorella; Fiore, Enrichetta Maria; Fleck, Martin Gabriel; Floris, Michele; Foertsch, Siegfried Valentin; Foka, Panagiota; Fokin, Sergey; Fragiacomo, Enrico; Francescon, Andrea; Frankenfeld, Ulrich Michael; Fuchs, Ulrich; Furget, Christophe; Furs, Artur; Fusco Girard, Mario; Gaardhoeje, Jens Joergen; Gagliardi, Martino; Gago Medina, Alberto Martin; Gallio, Mauro; Gangadharan, Dhevan Raja; Ganoti, Paraskevi; Gao, Chaosong; Garabatos Cuadrado, Jose; Garcia-Solis, Edmundo Javier; Gargiulo, Corrado; Gasik, Piotr Jan; Germain, Marie; Gheata, Andrei George; Gheata, Mihaela; Ghosh, Premomoy; Ghosh, Sanjay Kumar; Gianotti, Paola; Giubellino, Paolo; Giubilato, Piero; Gladysz-Dziadus, Ewa; Glassel, Peter; Gomez Ramirez, Andres; Gonzalez Zamora, Pedro; Gorbunov, Sergey; Gorlich, Lidia Maria; Gotovac, Sven; Grabski, Varlen; Graczykowski, Lukasz Kamil; Grelli, Alessandro; Grigoras, Alina Gabriela; Grigoras, Costin; Grigoryev, Vladislav; Grigoryan, Ara; Grigoryan, Smbat; Grynyov, Borys; Grion, Nevio; Grosse-Oetringhaus, Jan Fiete; Grossiord, Jean-Yves; Grosso, Raffaele; Guber, Fedor; Guernane, Rachid; Guerzoni, Barbara; Gulbrandsen, Kristjan Herlache; Gulkanyan, Hrant; Gunji, Taku; Gupta, Anik; Gupta, Ramni; Haake, Rudiger; Haaland, Oystein Senneset; Hadjidakis, Cynthia Marie; Haiduc, Maria; Hamagaki, Hideki; Hamar, Gergoe; Hanratty, Luke David; Hansen, Alexander; Harris, John William; Hartmann, Helvi; Harton, Austin Vincent; Hatzifotiadou, Despina; Hayashi, Shinichi; Heckel, Stefan Thomas; Heide, Markus Ansgar; Helstrup, Haavard; Herghelegiu, Andrei Ionut; Herrera Corral, Gerardo Antonio; Hess, Benjamin Andreas; Hetland, Kristin Fanebust; Hilden, Timo Eero; Hillemanns, Hartmut; Hippolyte, Boris; Hristov, Peter Zahariev; Huang, Meidana; Humanic, Thomas; Hussain, Nur; Hussain, Tahir; Hutter, Dirk; Hwang, Dae Sung; Ilkaev, Radiy; Ilkiv, Iryna; Inaba, Motoi; Ionita, Costin; Ippolitov, Mikhail; Irfan, Muhammad; Ivanov, Marian; Ivanov, Vladimir; Izucheev, Vladimir; Jacobs, Peter Martin; Jahnke, Cristiane; Jang, Haeng Jin; Janik, Malgorzata Anna; Pahula Hewage, Sandun; Jena, Chitrasen; Jena, Satyajit; Jimenez Bustamante, Raul Tonatiuh; Jones, Peter Graham; Jung, Hyungtaik; Jusko, Anton; Kalinak, Peter; Kalweit, Alexander Philipp; Kamin, Jason Adrian; Kang, Ju Hwan; Kaplin, Vladimir; Kar, Somnath; Karasu Uysal, Ayben; Karavichev, Oleg; Karavicheva, Tatiana; Karpechev, Evgeny; Kebschull, Udo Wolfgang; Keidel, Ralf; Keijdener, Darius Laurens; Keil, Markus; Khan, Kamal; Khan, Mohammed Mohisin; Khan, Palash; Khan, Shuaib Ahmad; Khanzadeev, Alexei; Kharlov, Yury; Kileng, Bjarte; Kim, Beomkyu; Kim, Do Won; Kim, Dong Jo; Kim, Hyeonjoong; Kim, Jinsook; Kim, Mimae; Kim, Minwoo; Kim, Se Yong; Kim, Taesoo; Kirsch, Stefan; Kisel, Ivan; Kiselev, Sergey; Kisiel, Adam Ryszard; Kiss, Gabor; Klay, Jennifer Lynn; Klein, Carsten; Klein, Jochen; Klein-Boesing, Christian; Kluge, Alexander; Knichel, Michael Linus; 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Lee, Graham Richard; Lee, Seongjoo; Legrand, Iosif; Lehnert, Joerg Walter; Lemmon, Roy Crawford; Lenti, Vito; Leogrande, Emilia; Leon Monzon, Ildefonso; Leoncino, Marco; Levai, Peter; Li, Shuang; Li, Xiaomei; Lien, Jorgen Andre; Lietava, Roman; Lindal, Svein; Lindenstruth, Volker; Lippmann, Christian; Lisa, Michael Annan; Ljunggren, Hans Martin; Lodato, Davide Francesco; Lonne, Per-Ivar; Loggins, Vera Renee; Loginov, Vitaly; Loizides, Constantinos; Lopez, Xavier Bernard; Lopez Torres, Ernesto; Lowe, Andrew John; Lu, Xianguo; Luettig, Philipp Johannes; Lunardon, Marcello; Luparello, Grazia; Maevskaya, Alla; Mager, Magnus; Mahajan, Sanjay; Mahmood, Sohail Musa; Maire, Antonin; Majka, Richard Daniel; Malaev, Mikhail; Maldonado Cervantes, Ivonne Alicia; Malinina, Liudmila; Mal'Kevich, Dmitry; Malzacher, Peter; Mamonov, Alexander; Manceau, Loic Henri Antoine; Manko, Vladislav; Manso, Franck; Manzari, Vito; Marchisone, Massimiliano; Mares, Jiri; Margagliotti, Giacomo Vito; Margotti, Anselmo; Margutti, Jacopo; Marin, Ana Maria; Markert, Christina; Marquard, Marco; Martashvili, Irakli; Martin, Nicole Alice; Martin Blanco, Javier; Martinengo, Paolo; Martinez Hernandez, Mario Ivan; Martinez-Garcia, Gines; Martinez Pedreira, Miguel; Martynov, Yevgen; Mas, Alexis Jean-Michel; Masciocchi, Silvia; Masera, Massimo; Masoni, Alberto; Massacrier, Laure Marie; Mastroserio, Annalisa; Matyja, Adam Tomasz; Mayer, Christoph; Mazer, Joel Anthony; Mazzoni, Alessandra Maria; Mcdonald, Daniel; Meddi, Franco; Menchaca-Rocha, Arturo Alejandro; Meninno, Elisa; Mercado-Perez, Jorge; Meres, Michal; Miake, Yasuo; Mieskolainen, Matti Mikael; Mikhaylov, Konstantin; Milano, Leonardo; Milosevic, Jovan; Minervini, Lazzaro Manlio; Mischke, Andre; Mishra, Aditya Nath; Miskowiec, Dariusz Czeslaw; Mitra, Jubin; Mitu, Ciprian Mihai; Mohammadi, Naghmeh; Mohanty, Bedangadas; Molnar, Levente; Montano Zetina, Luis Manuel; Montes Prado, Esther; Morando, Maurizio; Moreira De Godoy, Denise Aparecida; Moretto, Sandra; 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Tveter, Trine Spedstad; Ullaland, Kjetil; Uras, Antonio; Usai, Gianluca; Utrobicic, Antonija; Vajzer, Michal; Vala, Martin; Valencia Palomo, Lizardo; Vallero, Sara; Van Der Maarel, Jasper; Van Hoorne, Jacobus Willem; Van Leeuwen, Marco; Vanat, Tomas; Vande Vyvre, Pierre; Varga, Dezso; Diozcora Vargas Trevino, Aurora; Vargyas, Marton; Varma, Raghava; Vasileiou, Maria; Vasiliev, Andrey; Vauthier, Astrid; Vechernin, Vladimir; Veen, Annelies Marianne; Veldhoen, Misha; Velure, Arild; Venaruzzo, Massimo; Vercellin, Ermanno; Vergara Limon, Sergio; Vernet, Renaud; Verweij, Marta; Vickovic, Linda; Viesti, Giuseppe; Viinikainen, Jussi Samuli; Vilakazi, Zabulon; Villalobos Baillie, Orlando; Vinogradov, Alexander; Vinogradov, Leonid; Vinogradov, Yury; Virgili, Tiziano; Vislavicius, Vytautas; Viyogi, Yogendra; Vodopyanov, Alexander; Volkl, Martin Andreas; Voloshin, Kirill; Voloshin, Sergey; Volpe, Giacomo; Von Haller, Barthelemy; Vorobyev, Ivan; Vranic, Danilo; Vrlakova, Janka; Vulpescu, Bogdan; Vyushin, Alexey; Wagner, Boris; Wagner, Jan; Wang, Hongkai; Wang, Mengliang; Wang, Yifei; Watanabe, Daisuke; Weber, Michael; Weber, Steffen Georg; Wessels, Johannes Peter; Westerhoff, Uwe; Wiechula, Jens; Wikne, Jon; Wilde, Martin Rudolf; Wilk, Grzegorz Andrzej; Wilkinson, Jeremy John; Williams, Crispin; Windelband, Bernd Stefan; Winn, Michael Andreas; Yaldo, Chris G; Yamaguchi, Yorito; Yang, Hongyan; Yang, Ping; Yano, Satoshi; Yasnopolskiy, Stanislav; Yin, Zhongbao; Yokoyama, Hiroki; Yoo, In-Kwon; Yurchenko, Volodymyr; Yushmanov, Igor; Zaborowska, Anna; Zaccolo, Valentina; Zaman, Ali; Zampolli, Chiara; Correia Zanoli, Henrique Jose; Zaporozhets, Sergey; Zarochentsev, Andrey; Zavada, Petr; Zavyalov, Nikolay; Zbroszczyk, Hanna Paulina; Zgura, Sorin Ion; Zhalov, Mikhail; Zhang, Haitao; Zhang, Xiaoming; Zhang, Yonghong; Zhao, Chengxin; Zhigareva, Natalia; Zhou, Daicui; Zhou, You; Zhou, Zhuo; Zhu, Hongsheng; Zhu, Jianhui; Zhu, Xiangrong; Zichichi, Antonino; Zimmermann, Alice; Zimmermann, Markus Bernhard; Zinovjev, Gennady; Zyzak, Maksym

    2015-08-17

    The measurement of the mass differences for systems bound by the strong force has reached a very high precision with protons and anti-protons. The extension of such measurement from (anti-)baryons to (anti-)nuclei allows one to probe any difference in the interactions between nucleons and anti-nucleons encoded in the (anti-)nuclei masses. This force is a remnant of the underlying strong interaction among quarks and gluons and can be described by effective theories, but cannot yet be directly derived from quantum chromodynamics. Here we report a measurement of the difference between the ratios of the mass and charge of deuterons (d) and anti-deuterons ($\\bar{d}$), and $^{3}{\\rm He}$ and $^3\\overline{\\rm He}$ nuclei carried out with the ALICE (A Large Ion Collider Experiment) detector in Pb-Pb collisions at a centre-of-mass energy per nucleon pair of 2.76 TeV. Our direct measurement of the mass-over-charge differences confirm CPT invariance to an unprecedented precision in the sector of light nuclei. This funda...

  5. Turbine Blade Cooling System Optimization

    OpenAIRE

    GIRARDEAU, Julian; PAILHES, Jérôme; SEBASTIAN, Patrick; PARDO, Frédéric; Nadeau, Jean-Pierre

    2013-01-01

    The authors wish to thank turbine designers from TURBOMECA SAFRAN Group.; International audience; Designing high performance cooling systems suitable for preserving the service lifetime of nozzle guide vanes of turboshaft engines leads to significant aerodynamic losses. These losses jeopardize the performance of the whole engine. In the same time, a low efficiency cooling system may affect the costs of maintenance repair and overhaul of the engine as component life decreases. Consequently, de...

  6. DETERMINATION OF RADIATOR COOLING SURFACE

    Directory of Open Access Journals (Sweden)

    A. I. Yakubovich

    2009-01-01

    Full Text Available The paper proposes a methodology for calculation of a radiator cooling surface with due account of heat transfer non-uniformity on depth of its core. Calculation of radiator cooling surfaces of «Belarus-1221» and «Belarus-3022» tractors has been carried out in the paper. The paper also advances standard size series of radiators for powerful «Belarus» tractor type.

  7. Quantum limit of photothermal cooling

    CERN Document Server

    De Liberato, Simone; Nori, Franco

    2010-01-01

    We study the problem of cooling a mechanical oscillator using the photothermal (bolometric) force. Contrary to previous attempts to model this system, we take into account the noise effects due to the granular nature of photon absorption. This allows us to tackle the cooling problem down to the noise dominated regime and to find reasonable estimates for the lowest achievable phonon occupation in the cantilever.

  8. Cooling Shelf For Electronic Equipment

    Science.gov (United States)

    Tanzer, Herbert J.

    1989-01-01

    Heat-pipe action cools and maintains electronics at nearly constant temperature. System designed to control temperatures of spacecraft shelves or baseplates by combining honeycomb sandwich panel with reservoir of noncondensable gas and processing resulting device as variable-conductance heat pipe. Device provides flat surface for mounting heat-dissipating electronics that is effectively cooled and maintained at nearly constant temperature. Potentially useful in freeze drying, refrigeration, and air conditioning.

  9. Optical Tweezing Nuclei in the Cellular Blastoderm of Drosophila Embryos

    Science.gov (United States)

    Schoetz, Eva-Maria; Chaikin, Paul M.; Wieschaus, Eric F.

    2004-03-01

    Optical tweezers are used to manipulate nuclei in the syncytial blastoderm of Drosophila embryos. Our aim is to move a nucleus in a living embryo and study the reactions of its nearest neighbors to this displacement. Effects on the surrounding nuclei may allow us to test models in which actin-microtubule networks connect individual nuclei and keep them in place. In our experiments we use video analysis to follow individual nuclei using GFP-labeled histone protein. In a first approach, we were able to move nuclei in embryonic homogenates suspended in oil. Although the squashing destroys the cell, mitotic nuclear divisions continue, implying that the cytoskeleton, which connects the nuclei to the cortex, is still functioning. We will present studies of nuclear interactions in these squashes and in intact syncytial blastoderms.

  10. Spherical nuclei near the stability line and far from it

    Energy Technology Data Exchange (ETDEWEB)

    Isakov, V. I., E-mail: visakov@thd.pnpi.spb.ru [National Research Centre Kurchatov Institute, Petersburg Nuclear Physics Institute (Russian Federation)

    2016-11-15

    Results of microscopic and semiphenomenological calculations of features of spherical nuclei lying near the stability line and far from it are presented. The reason why the nuclei being considered are spherical is that they are magic at least in one nucleon sort. The present analysis is performed for Z = 50 and Z = 28 isotopes and for N = 50 isotones, the region extending from neutron-rich to neutron-deficient nuclei being covered. The isotopic dependence of the mean-field spin–orbit nuclear potential is revealed; systematics of energies of levels and probabilities for electromagnetic transitions is examined; and root-mean-square radii of nuclei are calculated, along with the proton- and neutron-density distributions in them. Nuclei in the vicinity of closed shells are considered in detail, and the axial-vector weak coupling constant in nuclei is evaluated. A systematic comparison of the results of calculations with experimental data is performed.

  11. Symmetry energy, unstable nuclei, and neutron star crusts

    CERN Document Server

    Iida, Kei

    2013-01-01

    Phenomenological approach to inhomogeneous nuclear matter is useful to describe fundamental properties of atomic nuclei and neutron star crusts in terms of the equation of state of uniform nuclear matter. We review a series of researches that we have developed by following this approach. We start with more than 200 equations of state that are consistent with empirical masses and charge radii of stable nuclei and then apply them to describe matter radii and masses of unstable nuclei, proton elastic scattering and total reaction cross sections off unstable nuclei, and nuclei in neutron star crusts including nuclear pasta. We finally discuss the possibility of constraining the density dependence of the symmetry energy from experiments on unstable nuclei and even observations of quasi-periodic oscillations in giant flares of soft gamma-ray repeaters.

  12. Symmetry energy, unstable nuclei and neutron star crusts

    Energy Technology Data Exchange (ETDEWEB)

    Iida, Kei [Kochi University, Department of Natural Science, Kochi (Japan); RIKEN Nishina Center, Saitama (Japan); Oyamatsu, Kazuhiro [RIKEN Nishina Center, Saitama (Japan); Aichi Shukutoku University, Department of Human Informatics, Aichi (Japan)

    2014-02-15

    The phenomenological approach to inhomogeneous nuclear matter is useful to describe fundamental properties of atomic nuclei and neutron star crusts in terms of the equation of state of uniform nuclear matter. We review a series of researches that we have developed by following this approach. We start with more than 200 equations of state that are consistent with empirical masses and charge radii of stable nuclei and then apply them to describe matter radii and masses of unstable nuclei, proton elastic scattering and total reaction cross sections off unstable nuclei, and nuclei in neutron star crusts including nuclear pasta. We finally discuss the possibility of constraining the density dependence of the symmetry energy from experiments on unstable nuclei and even observations of quasi-periodic oscillations in giant flares of soft gamma-ray repeaters. (orig.)

  13. Quantitative X-ray - UV Line and Continuum Spectroscopy with Application to AGN: State-Specific Hydrogenic Recombination Cooling Coefficients for a Wide Range of Conditions

    Science.gov (United States)

    LaMothe, J.; Ferland, Gary J.

    2002-01-01

    Recombination cooling, in which a free electron emits light while being captured to an ion, is an important cooling process in photoionized clouds that are optically thick or have low metallicity. State specific rather than total recombination cooling rates are needed since the hydrogen atom tends to become optically thick in high-density regimes such as Active Galactic Nuclei. This paper builds upon previous work to derive the cooling rate over the full temperature range where the process can be a significant contributor in a photoionized plasma. We exploit the fact that the recombination and cooling rates are given by intrinsically similar formulae to express the cooling rate in terms of the closely related radiative recombination rate. We give an especially simple but accurate approximation that works for any high hydrogenic level and can be conveniently employed in large-scale numerical simulations.

  14. Dual origin of pairing in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Idini, A. [University of Jyvaskyla, Department of Physics (Finland); Potel, G. [Michigan State University, National Superconducting Cyclotron Laboratory (United States); Barranco, F. [Escuela Superior de Ingenieros, Universidad de Sevilla, Departamento de Fìsica Aplicada III (Spain); Vigezzi, E., E-mail: enrico.vigezzi@mi.infn.it [INFN Sezione di Milano (Italy); Broglia, R. A. [Università di Milano, Dipartimento di Fisica (Italy)

    2016-11-15

    The pairing correlations of the nucleus {sup 120}Sn are calculated by solving the Nambu–Gor’kov equations, including medium polarization effects resulting from the interweaving of quasiparticles, spin and density vibrations, taking into account, within the framework of nuclear field theory (NFT), processes leading to self-energy and vertex corrections and to the induced pairing interaction. From these results one can not only demonstrate the inevitability of the dual origin of pairing in nuclei, but also extract information which can be used at profit to quantitatively disentangle the contributions to the pairing gap Δ arising from the bare and from the induced pairing interaction. The first is the strong {sup 1}S{sub 0} short-range NN potential resulting from meson exchange between nucleons moving in time reversal states within an energy range of hundreds of MeV from the Fermi energy. The second results from the exchange of vibrational modes between nucleons moving within few MeV from the Fermi energy. Short- (v{sub p}{sup bare}) and long-range (v{sub p}{sup ind}) pairing interactions contribute essentially equally to nuclear Cooper pair stability. That is to the breaking of gauge invariance in open-shell superfluid nuclei and thus to the order parameter, namely to the ground state expectation value of the pair creation operator. In other words, to the emergent property of generalized rigidity in gauge space, and associated rotational bands and Cooper pair tunneling between members of these bands.

  15. Nuclear obscuration in active galactic nuclei

    Science.gov (United States)

    Almeida, Cristina Ramos; Ricci, Claudio

    2017-10-01

    The material surrounding accreting supermassive black holes connects the active galactic nucleus with its host galaxy and, besides being responsible for feeding the black hole, provides important information on the feedback that nuclear activity produces on the galaxy. In this Review, we summarize our current understanding of the close environment of accreting supermassive black holes obtained from studies of local active galactic nuclei carried out in the infrared and X-ray regimes. The structure of this circumnuclear material is complex, clumpy and dynamic, and its covering factor depends on the accretion properties of the active galactic nucleus. In the infrared, this obscuring material is a transition zone between the broad- and narrow-line regions, and, at least in some galaxies, it consists of two structures: an equatorial disk/torus and a polar component. In the X-ray regime, the obscuration is produced by multiple absorbers across various spatial scales, mostly associated with the torus and the broad-line region. In the coming decade, the new generation of infrared and X-ray facilities will greatly contribute to our understanding of the structure and physical properties of nuclear obscuration in active galactic nuclei.

  16. Mid-infrared spectra of comet nuclei

    CERN Document Server

    Kelley, Michael S P; Gehrz, Robert D; Reach, William T; Harker, David E

    2016-01-01

    Jovian Trojan D-type asteroids have mid-infrared emissivity features strikingly similar to comet comae, suggesting that they have the same compositions and that the surfaces of the Trojans are highly porous. However, a direct comparison between a comet and asteroid surface has not been possible due to the paucity of spectra of comet nuclei at mid-infrared wavelengths. We present 5-35 {\\mu}m thermal emission spectra of comets 10P/Tempel 2, and 49P/Arend-Rigaux observed with the Infrared Spectrograph on the Spitzer Space Telescope. Our analysis suggests the spectra are dominated by the comet nucleus. We fit each spectrum with the near-Earth asteroid thermal model (NEATM) and find sizes in agreement with previous values. However, the NEATM beaming parameters of the nuclei, 0.74 to 0.83, are systematically lower than the Jupiter-family comet population mean of 1.03+/-0.11, derived from 16- and 22-{\\mu}m photometry. When the spectra are normalized by the NEATM model, a weak 10-{\\mu}m silicate plateau is evident, w...

  17. Superheavy nuclei: from predictions to discovery

    Science.gov (United States)

    Oganessian, Yu Ts; Sobiczewski, A.; Ter-Akopian, G. M.

    2017-02-01

    A fundamental outcome of modern nuclear microscopic theory is the prediction of the ‘islands of stability’ in the region of hypothetical superheavy elements (SHEs). In a heavy nucleus, going through the large-scale deformation on the way to fission, the motion of single nucleons is coupled with the collective degrees of freedom of the whole system. The most striking effect of this coupling is obtained for the case of fission of the heaviest nuclei, whose existence is defined entirely by the nuclear structure, i.e. by the shell effect. From this point of view, the synthesis and study of properties of superheavy nuclei (SHN) is a direct way for checking the basic statements of the microscopic nuclear theory. On the nuclide map, SHN outline the border of the heaviest nuclear masses. SHN set the limits of the periodic system of chemical elements. The study of possible existence of SHN in nature offers a way for testing different scenarios of astrophysical nucleosynthesis. The paper elucidates experimental approaches, used for testing the theory predictions made about the SHN, and presents the results of the discovery of the ‘stability island’ of SHEs.

  18. Incomprehensibility in finite nuclei and nuclear matter

    CERN Document Server

    Stone, J R; Moszkowski, S A

    2014-01-01

    The incompressibility (compression modulus) $K_{\\rm 0}$ of infinite symmetric nuclear matter at saturation density has become one of the major constraints on mean-field models of nuclear many-body systems as well as of models of high density matter in astrophysical objects and heavy-ion collisions. We present a comprehensive re-analysis of recent data on GMR energies in even-even $^{\\rm 112-124}$Sn and $^{\\rm 106,100-116}$Cd and earlier data on 58 $\\le$ A $\\le$ 208 nuclei. The incompressibility of finite nuclei $K_{\\rm A}$ is expressed as a leptodermous expansion with volume, surface, isospin and Coulomb coefficients $K_{\\rm vol}$, $K_{\\rm surf}$, $K_\\tau$ and $K_{\\rm coul}$. \\textit{Assuming} that the volume coefficient $K_{\\rm vol}$ is identified with $K_{\\rm 0}$, the $K_{\\rm coul}$ = -(5.2 $\\pm$ 0.7) MeV and the contribution from the curvature term K$_{\\rm curv}$A$^{\\rm -2/3}$ in the expansion is neglected, compelling evidence is found for $K_{\\rm 0}$ to be in the range 250 $ < K_{\\rm 0} < $ 315 MeV,...

  19. Energy Efficient Electronics Cooling Project

    Energy Technology Data Exchange (ETDEWEB)

    Steve O' Shaughnessey; Tim Louvar; Mike Trumbower; Jessica Hunnicutt; Neil Myers

    2012-02-17

    Parker Precision Cooling Business Unit was awarded a Department of Energy grant (DE-EE0000412) to support the DOE-ITP goal of reducing industrial energy intensity and GHG emissions. The project proposed by Precision Cooling was to accelerate the development of a cooling technology for high heat generating electronics components. These components are specifically related to power electronics found in power drives focused on the inverter, converter and transformer modules. The proposed cooling system was expected to simultaneously remove heat from all three of the major modules listed above, while remaining dielectric under all operating conditions. Development of the cooling system to meet specific customer's requirements and constraints not only required a robust system design, but also new components to support long system functionality. Components requiring further development and testing during this project included pumps, fluid couplings, cold plates and condensers. All four of these major categories of components are required in every Precision Cooling system. Not only was design a key area of focus, but the process for manufacturing these components had to be determined and proven through the system development.

  20. Proton scattering from unstable nuclei {sup 20}O, {sup 30}S, {sup 34}Ar: experimental study and models; Diffusion de protons sur les noyaux instables {sup 20}O, {sup 30}S, {sup 34}Ar: etude experimentale et developpement de modeles

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Elias [Institut de Physique Nucleaire, CNRS - IN2P3, Universite Paris - Sud, 91406 Orsay Cedex (France)

    2000-01-28

    Elastic and inelastic proton scattering from the unstable nuclei {sup 20}O, {sup 30}S and {sup 34}Ar were measured in inverse kinematics at the Grand Accelerateur National d'Ions Lourds. Secondary beams of {sup 20}O at 43 MeV/A, {sup 30}S at 53 MeV/A and {sup 34}Ar at 47 MeV/A impinged on a (CH{sub 2}){sub n} target. Recoiling protons were detected in the silicon strip array MUST. Energies and angular distributions of the first 2{sup +} and 3{sup -} states were measured. A phenomenological analysis yields values of the deformation parameters {beta}{sub 2} and {beta}{sub 3} of 0.55 (6) and 0.35 (5) for {sup 20}O, 0.32 (3) and 0.22 (4) for {sup 30}S, 0.27 (2) and 0.39 (3) for {sup 34}Ar, respectively, and allows the extraction of the ratio of neutron to proton transition matrix elements (M{sub n}/M{sub p})/(N/Z) for 2{sup +} states: 2.35 (37) for {sup 20}O, 0.93 (20) for {sup 30}S and 1.35 (28) for {sup 34}Ar. Therefore the proton rich nuclei {sup 30}S and {sup 34}Ar show a 2{sup +} excitation of isoscalar character whereas the excitation of {sup 20}O is of isovector character. In order to perform a microscopic analysis of the data, we have developed a QRPA model, using three Skyrme interaction: SIII, SG2, SLy4. This model reproduces measured B(EL) values for the oxygen, sulfur and argon isotopic chains, whereas RPA calculations, which do not take pairing into account, underestimate these values. In the case of the QRPA model the energies of the first 2{sup +} state are overestimated by about 1 MeV, but the evolution along the isotopic chains is well reproduced. (M{sub n}/M{sub p})/(N/Z) ratios for the first 2{sup +} state deduced from the microscopic analysis using QRPA are 1.98 for {sup 20}O, 1.05 for {sup 30}S and 1.00 for {sup 34}Ar, in agreement with the conclusions of the phenomenological analysis. However important discrepancies are observed between the two types of analysis for other isotopes, in particular neutron rich argon and sulfur nuclei. (author)

  1. Cluster radioactivity in very heavy nuclei: a new perspective

    OpenAIRE

    Routray, T. R.; Nayak, Jagajjaya; Basu, D. N.

    2008-01-01

    Exotic cluster decay of very heavy nuclei is studied using the microscopic nuclear potentials obtained by folding density dependent M3Y effective interaction with the densities of the cluster and the daughter nuclei. The microscopic nuclear potential, Coulomb interaction and the centrifugal barrier arising out of spin-parity conservation are used to obtain the potential between the cluster and the daughter nuclei. Half life values are calculated in the WKB framework and the preformation facto...

  2. Collisions of Small Nuclei in the Thermal Model

    CERN Document Server

    Cleymans, J; Oeschler, H.; Redlich, K.; Sharma, N.

    2016-01-01

    An analysis is presented of the expectations of the thermal model for particle production in collisions of small nuclei. The maxima observed in particle ratios of strange particles to pions as a function of beam energy in heavy ion collisions, are reduced when considering smaller nuclei. Of particular interest is the $\\Lambda/\\pi^+$ ratio shows the strongest maximum which survives even in collisions of small nuclei.

  3. Cryogenic cooling system for HTS cable

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Shigeru [Taiyo Nippon Sanso, Tsukuba (Japan)

    2017-06-15

    Recently, Research and development activity of HTS (High Temperature Superconducting) power application is very progressive worldwide. Especially, HTS cable system and HTSFCL (HTS Fault current limiter) system are proceeding to practical stages. In such system and equipment, cryogenic cooling system, which makes HTS equipment cooled lower than critical temperature, is one of crucial components. In this article, cryogenic cooling system for HTS application, mainly cable, is reviewed. Cryogenic cooling system can be categorized into conduction cooling system and immersion cooling system. In practical HTS power application area, immersion cooling system with sub-cooled liquid nitrogen is preferred. The immersion cooling system is besides grouped into open cycle system and closed cycle system. Turbo-Brayton refrigerator is a key component for closed cycle system. Those two cooling systems are focused in this article. And, each design and component of the cooling system is explained.

  4. Microtextured Surfaces for Turbine Blade Impingement Cooling

    Science.gov (United States)

    Fryer, Jack

    2014-01-01

    Gas turbine engine technology is constantly challenged to operate at higher combustor outlet temperatures. In a modern gas turbine engine, these temperatures can exceed the blade and disk material limits by 600 F or more, necessitating both internal and film cooling schemes in addition to the use of thermal barrier coatings. Internal convective cooling is inadequate in many blade locations, and both internal and film cooling approaches can lead to significant performance penalties in the engine. Micro Cooling Concepts, Inc., has developed a turbine blade cooling concept that provides enhanced internal impingement cooling effectiveness via the use of microstructured impingement surfaces. These surfaces significantly increase the cooling capability of the impinging flow, as compared to a conventional untextured surface. This approach can be combined with microchannel cooling and external film cooling to tailor the cooling capability per the external heating profile. The cooling system then can be optimized to minimize impact on engine performance.

  5. A novel ion cooling trap for multi-reflection time-of-flight mass spectrograph

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Y., E-mail: yito@riken.jp [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Schury, P. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); New Mexico State University, Department Chemistry and Biochemistry, Las Cruces, NM 88003 (United States); Wada, M.; Naimi, S. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Smorra, C. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Sonoda, T. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Mita, H. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Takamine, A. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Aoyama Gakuin University, 4-4-25 Shibuya, Shibuya-ku, Tokyo 150-8366 (Japan); Okada, K. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554 (Japan); Ozawa, A. [University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Wollnik, H. [SLOWRI Team, Nishina Accelerator-Based Research Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); New Mexico State University, Department Chemistry and Biochemistry, Las Cruces, NM 88003 (United States)

    2013-12-15

    Highlights: • Fast cooling time: 2 ms. • High efficiency: ≈27% for {sup 23}Na{sup +} and ≈5.1% for {sup 7}Li{sup +}. • 100% Duty cycle with double trap system. -- Abstract: A radiofrequency quadrupole ion trap system for use with a multi-reflection time-of-flight mass spectrograph (MRTOF) for short-lived nuclei has been developed. The trap system consists of two different parts, an asymmetric taper trap and a flat trap. The ions are cooled to a sufficient small bunch for precise mass measurement with MRTOF in only 2 ms cooling time in the flat trap, then orthogonally ejected to the MRTOF for mass analysis. A trapping efficiency of ≈27% for {sup 23}Na{sup +} and ≈5.1% for {sup 7}Li{sup +} has been achieved.

  6. The isovector dipole strength in nuclei with extreme neutron excess

    CERN Document Server

    Arteaga, Daniel Pena; Ring, Peter

    2008-01-01

    The E1 strength is systematically analyzed in very neutron-rich Sn nuclei, beyond $^{132}$Sn until $^{166}$Sn, within the Relativistic Quasiparticle Random Phase Approximation. The great neutron excess favors the appearance of a deformed ground state for $^{142-162}$Sn. The evolution of the low-lying strength in deformed nuclei is determined by the interplay of two factors, isospin asymmetry and deformation: while greater neutron excess increases the total low-lying strength, deformation hinders and spreads it. Very neutron rich deformed nuclei may not be as good candidates as stable spherical nuclei like $^{132}$Sn for the experimental study of low-lying E1 strength.

  7. Study of nuclear level densities for exotic nuclei

    Directory of Open Access Journals (Sweden)

    M Nasri Nasrabadi

    2012-06-01

    Full Text Available Nuclear level density (NLD is one of the properties of nuclei with widespread applications in astrophysics and nuclear medicine. Since there has been little experimental and theoretical research on the study of nuclei which are far from stability line, studying NLD for these nuclei is of crucial importance. Also, as NLD is an important input for nuclear research codes, hence studying the methods for calculation of this parameter is essential. Besides introducing various methods and models for calculating NLD for practical applications, we used exact spectra distribution (SPDM for determining NLD of two neutron and proton enriched exotic nuclei with the same mass number.

  8. Floor cooling and air-cooling, the effects on thermal comfort or different cooling systems

    Energy Technology Data Exchange (ETDEWEB)

    Sijpheer, N.C.; Bakker, E.J.; Ligthart, F.A.T.M.; Opstelten, I.J. [ECN Energie in de Gebouwde Omgeving en Netten, Petten (Netherlands)

    2007-09-15

    One of the research areas of the Energy research Centre of the Netherlands (ECN) concerns the built environment. Several facilities to conduct research activities are at ECN's disposal. One of these facilities, are five research dwellings located on the premises of ECN. Measured data from these facilities together with weather data and computer models are used to evaluate innovative energy concepts and components in energy systems. Experiments with different cooling systems in ECN's research dwellings are executed to evaluate their effective influence on both energy use and thermal comfort. Influence of inhabitants' behaviour is taken into account in these experiments. The thermal comfort is indicated by the Predicted Mean Vote (PMV) as defined by P.O. Fanger. For this paper, the results of measurements with a floor cooling and air cooling system are assessed. Effects on the PMV measured during experiments with the two different cooling systems will be presented.

  9. Cosmic ray heating in cool core clusters I: diversity of steady state solutions

    CERN Document Server

    Jacob, Svenja

    2016-01-01

    The absence of large cooling flows in cool core clusters appears to require self-regulated energy feedback by active galactic nuclei (AGNs) but the exact heating mechanism has not yet been identified. Here, we analyse whether a combination of cosmic ray (CR) heating and thermal conduction can offset radiative cooling. To this end, we compile a large sample of 39 cool core clusters and determine steady state solutions of the hydrodynamic equations that are coupled to the CR energy equation. We find stable solutions that match the observed density and temperature profiles for all our clusters well. Radiative cooling is balanced by CR heating in the cluster centres and by thermal conduction on larger scales, thus demonstrating the relevance of both heating mechanisms. Our mass deposition rates vary by three orders of magnitude and are linearly correlated to the observed star formation rates. Clusters with large mass deposition rates show larger cooling radii and require a larger radial extent of the CR injection...

  10. AGN Feedback and Cooling Flows: The Failure of Simple Hydrodynamical Models

    CERN Document Server

    Vernaleo, J C; Vernaleo, John C.; Reynolds, Christopher S.

    2005-01-01

    In recent years it has become increasingly clear that Active Galactic Nuclei, and radio-galaxies in particular, have an impact on large scale structure and galaxy formation. In principle, radio-galaxies are energetic enough to halt the cooling in the inner regions clusters, solving the cooling flow problem and explaining the high-mass truncation of the galaxy luminosity function. We explore this process through a series of high resolution, three dimensional hydrodynamic simulations of jetted active galaxies which act in response to cooling-mediated accretion of an ICM atmosphere. We find that such models are incapable of producing a long term balance of heating and cooling; catastrophic cooling can be delayed by the jet action but inevitably takes hold. At the heart of the failure of these models is the formation of a low density channel through which the jet can freely flow, carrying its energy out of the cooling core. While this obviously highlights the need to include physics beyond the ideal hydrodynamics...

  11. Star Formation Efficiency in the Cool Cores of Galaxy Clusters

    Science.gov (United States)

    McDonald, Michael; Veilleux, Sylvain; Rupke, David S. N.; Mushotzky, Richard; Reynolds, Christopher

    2011-06-01

    We have assembled a sample of high spatial resolution far-UV (Hubble Space Telescope Advanced Camera for Surveys/Solar Blind Channel) and Hα (Maryland-Magellan Tunable Filter) imaging for 15 cool core galaxy clusters. These data provide a detailed view of the thin, extended filaments in the cores of these clusters. Based on the ratio of the far-UV to Hα luminosity, the UV spectral energy distribution, and the far-UV and Hα morphology, we conclude that the warm, ionized gas in the cluster cores is photoionized by massive, young stars in all but a few (A1991, A2052, A2580) systems. We show that the extended filaments, when considered separately, appear to be star forming in the majority of cases, while the nuclei tend to have slightly lower far-UV luminosity for a given Hα luminosity, suggesting a harder ionization source or higher extinction. We observe a slight offset in the UV/Hα ratio from the expected value for continuous star formation which can be modeled by assuming intrinsic extinction by modest amounts of dust (E(B - V) ~ 0.2) or a top-heavy initial mass function in the extended filaments. The measured star formation rates vary from ~0.05 M sun yr-1 in the nuclei of non-cooling systems, consistent with passive, red ellipticals, to ~5 M sun yr-1 in systems with complex, extended, optical filaments. Comparing the estimates of the star formation rate based on UV, Hα, and infrared luminosities to the spectroscopically determined X-ray cooling rate suggests a star formation efficiency of 14+18 - 8%. This value represents the time-averaged fraction, by mass, of gas cooling out of the intracluster medium, which turns into stars and agrees well with the global fraction of baryons in stars required by simulations to reproduce the stellar mass function for galaxies. This result provides a new constraint on the efficiency of star formation in accreting systems.

  12. Bunched Beam Cooling in the Fermilab Recycler

    CERN Document Server

    Neuffer, David V; Burov, Alexey; Nagaitsev, Sergei

    2005-01-01

    Stochastic cooling with bunched beam in a linear bucket has been obtained and implemented operationally in the fermilab recycler. In this implementation the particle bunch length is much greater than the cooling system wavelengths. The simultaneous longitudinal bunching enables cooling to much smaller longitudinal emittances than the coasting beam or barrier bucket system. Characteristics and limitations of bunched beam stochastic cooling are discussed.

  13. A new Newton's law of cooling?

    Science.gov (United States)

    Kleiber, M

    1972-12-22

    Several physiologists confuse Fourier's law of animal heat flow with Newton's law of cooling. A critique of this error in 1932 remained ineffective. In 1969 Molnar tested Newton's cooling law. In 1971 Strunk found Newtonian cooling unrealistic for animals. Unfortunately, he called the Fourier formulation of animal heat flow, requiring post-Newtonian observations, a "contemporary Newtonian law of cooling."

  14. 14 CFR 25.1043 - Cooling tests.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Cooling tests. 25.1043 Section 25.1043... STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Cooling § 25.1043 Cooling tests. (a) General. Compliance... during the cooling tests must be the minimum grade approved for the engines, and the mixture...

  15. 14 CFR 27.1043 - Cooling tests.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Cooling tests. 27.1043 Section 27.1043... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Cooling § 27.1043 Cooling tests. (a) General. For the tests... during the cooling tests must be of the minimum grade approved for the engines, and the mixture...

  16. 14 CFR 29.1043 - Cooling tests.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Cooling tests. 29.1043 Section 29.1043... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Cooling § 29.1043 Cooling tests. (a) General. For the... (a)(1) of this section may exceed established limits. (3) The fuel used during the cooling tests...

  17. 14 CFR 29.908 - Cooling fans.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Cooling fans. 29.908 Section 29.908... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant General § 29.908 Cooling fans. For cooling fans that are a part of a powerplant installation the following apply: (a) Category A. For cooling fans...

  18. 14 CFR 23.1043 - Cooling tests.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Cooling tests. 23.1043 Section 23.1043... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Cooling § 23.1043 Cooling... established limits. (3) The fuel used during the cooling tests must be of the minimum grade approved for...

  19. Impingement jet cooling in gas turbines

    CERN Document Server

    Amano, R S

    2014-01-01

    Due to the requirement for enhanced cooling technologies on modern gas turbine engines, advanced research and development has had to take place in field of thermal engineering. Impingement jet cooling is one of the most effective in terms of cooling, manufacturability and cost. This is the first to book to focus on impingement cooling alone.

  20. New cooling regulation technology of secondary cooling station in DCS

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xuan; Yan, Jun-wei; Zhu, Dong-sheng; Liu, Fei-long; Lei, Jun-xi [The Key Lab of Enhanced Heat Transfer and Energy Conservation of Ministry of Education, School of Chemical and Energy Engineering, South China University of Technology, Guangzhou 510641 (China); Liang, Lie-quan [The Key Lab of E-Commerce Market Application Technology of Guangdong Province, Guangdong University of Business Studies, Guangzhou 510320 (China)

    2008-07-01

    In this paper, a kind of new control technology of secondary cooling station (constant flow rate/variable temperature difference) in district cooling system (DCS) is proposed in view of serial consequences including low efficiency and high operating cost caused by low temperature of supply water in DCS. This technology has been applied in DCS of Guangzhou University City. The result has already indicated that such technology can increase the supply and return temperatures of buildings, return water temperature of primary side in the plate heat exchanger unit, moreover, the efficiency of both the chiller and the whole system are improved significantly. (author)

  1. Cooling Efficiency of Laminar Cooling System for Plate Mill

    Institute of Scientific and Technical Information of China (English)

    ZHANG Dian-hua; WANG Bing-xing; ZHOU Na; YU Ming; WANG Jun

    2008-01-01

    Heat transfer was researched from a perspective of the industry application.On the basis of the first law of thermodynamics,the cooling efficiency was deduced from the change of enthalpy inside hot plate.The relationship between the cooling efficiency and its influencing parameters was regressed from plenty of data collected from the worksite and discussed in detail.The temperature profiles resulting from the online model and the model modified by regressed formulas were presented and compared.The results indicated that the control accuracy of the modified model was increased obviously.

  2. Power spectra of active galactic nuclei

    Institute of Scientific and Technical Information of China (English)

    WANG TaiShan; WU YuXiang; LIU Yuan

    2009-01-01

    The power spectral densities (PSDs) for a sample of active galactic nuclei (AGNs) are analyzed in both the frequency domain and the time domain. We find for each object that for broadband noise a character timescale-bifurcation timescale of Fourier and time-domain PSD exists in the 103-106 s range,below which the time-domain power spectrum is systematically higher than the corresponding Fourier spectrum. The relationship between bifurcation timescale, AGN mass and luminosity is studied. Compared with the fact that similar phenomena have been found for Galactic black hole candidates (GBHs)with bifurcation timescale ~0.1 s but not for accreting neutron stars, our finding indicates that AGNs and GBHs have common intrinsic nature in rapid X-ray variability with a character time parameter scaled with their masses.

  3. Power spectra of active galactic nuclei

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The power spectral densities(PSDs)for a sample of active galactic nuclei(AGNs)are analyzed in both the frequency domain and the time domain.We find for each object that for broadband noise a character timescale-bifurcation timescale of Fourier and time-domain PSD exists in the 10 3 -10 6 s range, below which the time-domain power spectrum is systematically higher than the corresponding Fourier spectrum.The relationship between bifurcation timescale,AGN mass and luminosity is studied.Compared with the fact that similar phenomena have been found for Galactic black hole candidates(GBHs) with bifurcation timescale~0.1 s but not for accreting neutron stars,our finding indicates that AGNs and GBHs have common intrinsic nature in rapid X-ray variability with a character time parameter scaled with their masses.

  4. Are cometary nuclei primordial rubble piles?

    Science.gov (United States)

    Weissman, P. R.

    1986-01-01

    Whipple's icy conglomerate model for the cometary nucleus has had considerable sucess in explaining a variety of cometary phenomena such as gas production rates and nongravitational forces. However, as discussed here, both observational evidence and theoretical considerations suggest that the cometary nucleus may not be a well-consolidated single body, but may instead be a loosely bound agglomeration of smaller fragments, weakly bonded and subject to occasional or even frequent disruptive events. The proposed model is analogous to the 'rubble pile' model suggested for the larger main-belt asteroids, although the larger cometary fragments are expected to be primordial condensations rather than collisionally derived debris as in the asteroid case. The concept of cometary nuclei as primordial rubble piles is proposed as a modification of the basic Whipple model, not as a replacement for it.

  5. Active Galactic Nuclei Feedback and Clusters

    Indian Academy of Sciences (India)

    Biman B. Nath

    2011-12-01

    The Intracluster Medium (ICM) is believed to have been affected by feedback from Active Galactic Nuclei (AGN) and/or supernovae-driven winds. These sources are supposed to have injected entropy into the ICM gas. The recently determined universal pressure profile of the ICM gas has been used and after comparing with the entropy profile of the gas from gravitational effects of the dark matter halo, the additional entropy injected by non-gravitational sources, as a function of the total cluster mass is determined. The current observational data of red-shift evolution of cluster scaling relation is shown that allow models in which the entropy injection decreases at high red-shift.

  6. Correlations of Active Galactic Nuclei with Microquasars

    Institute of Scientific and Technical Information of China (English)

    YE Yong-Chun; ZUO Xue-Qin; WANG Ding-Xiong

    2006-01-01

    Correlations of active galactic nuclei (AGNs) with microquasars are discussed based on the coexistence of the Blandford-Znajek (BZ) and magnetic coupling (MC) processes (CEBZMC) in black hole (BH) accretion disk.The proportions of several quantities of BH systems for both AGNs and microquasars are derived by combining the observational data with CEBZMC. It is shown that the square of the magnetic field at the BH horizon is inversely proportional to the BH mass, while the accretion rate of the disk is proportional to the BH mass. In addition, the very steep emissivity indexes from the recent XMM-Newton observations of the nearby bright Seyfert 1 galaxy MCG-6-30-15 and the microquasars XTE J1650-500 are well fitted by considering the MC effects on the disk radiation. These results suggest strongly the correlations of A GNs with microquasars.

  7. Single-particle states in transcurium nuclei.

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, I.

    1999-09-30

    Identification of single-particle states in the heaviest known nuclei is important because their energies can be used to test the single-particle potential in these high-Z elements. These states can be identified by studying the decay schemes of very heavy odd-mass nuclides. For neutrons, the heaviest odd-mass nuclide available in milliCurie quantities is the 20-h {sup 255}Fm and for protons the heaviest nuclide available is the 20-d {sup 253}Es. These two isotopes were obtained from the Transplutonium Element Production Program at Oak Ridge and their spectra were measured with high-resolution germanium spectrometers. From the results of these measurements we have identified states in {sup 251}Cf and {sup 249}Bk up to 1 MeV excitation energy.

  8. Viscosity: From air to hot nuclei

    Indian Academy of Sciences (India)

    Nguyen Dinh Dang

    2014-11-01

    After a brief review of the history of viscosity from classical to quantal fluids, a discussion of how the shear viscosity of a finite hot nucleus is calculated directly from the width and energy of the giant dipole resonance (GDR) of the nucleus is given in this paper. The ratio / with s being the entropy volume density, is extracted from the experimental systematic of GDR in copper, tin and lead isotopes at finite temperature . These empirical results are compared with the results predicted by several independent models, as well as with almost model-independent estimations. Based on these results, it is concluded that the ratio / in medium and heavy nuclei decreases with increasing to reach (1.3−4)$×\\hbar/(4 k_B)$ at = 5 MeV, which is almost the same as that obtained for quark-gluon plasma at > 170 MeV.

  9. Neutrino Nucleosynthesis of radioactive nuclei in supernovae

    CERN Document Server

    Sieverding, A; Langanke, K; Martínez-Pinedo, G; Heger, A

    2015-01-01

    We study the neutrino-induced production of nuclides in explosive supernova nucleosynthesis for progenitor stars with solar metallicity and initial main sequence masses between 15 M$_\\odot$ and 40 M$_\\odot$. We improve previous investigations i) by using a global set of partial differential cross sections for neutrino-induced charged- and neutral-current reactions on nuclei with charge numbers $Z < 76 $ and ii) by considering modern supernova neutrino spectra which have substantially lower average energies compared to those previously adopted in neutrino nucleosynthesis studies. We confirm the production of $^7$Li, $^{11}$B, $^{138}$La, and $^{180}$Ta by neutrino nucleosynthesis, albeit at slightly smaller abundances due to the changed neutrino spectra. We find that for stars with a mass smaller than 20 M$_\\odot$, $^{19}$F is produced mainly by explosive nucleosynthesis while for higher mass stars it is produced by the $\

  10. Compressed Baryonic Matter: from Nuclei to Pulsars

    CERN Document Server

    Xu, Renxin

    2013-01-01

    Our world is wonderful because of the negligible baryonic part although unknown dark matter and dark energy dominate the Universe. Those nuclei in the daily life are forbidden to fuse by compression due to the Coulomb repulse, nevertheless, it is usually unexpected in extraterrestrial extreme-environments: the gravity in a core of massive evolved star is so strong that all the other forces (including the Coulomb one) could be neglected. Compressed baryonic matter is then produced after supernova, manifesting itself as pulsar-like stars observed. The study of this compressed baryonic matter can not only be meaningful in fundamental physics (e.g., the elementary color interaction at low-energy scale, testing gravity theories, detecting nano-Hertz background gravitational waves), but has also profound implications in engineering applications (including time standard and navigation), and additionally, is focused by Chinese advanced telescopes, either terrestrial or in space. Historically, in 1930s, L. Landau spec...

  11. Eta-mesic nuclei: past, present, future

    CERN Document Server

    Haider, Q

    2015-01-01

    Eta-mesic nucleus or the quasibound nuclear state of an eta ($\\eta$) meson in a nucleus is caused by strong-interaction force alone. This new type of nuclear species, which extends the landscape of nuclear physics, has been extensively studied since its prediction in 1986. In this paper, we review and analyze in great detail the models of the fundamental $\\eta$--nucleon interaction leading to the formation of an $\\eta$--mesic nucleus, the methods used in calculating the properties of a bound $\\eta$, and the approaches employed in the interpretation of the pertinent experimental data. In view of the successful observation of the $\\eta$--mesic nucleus $^{25}$Mg$_{\\eta}$ and other promising experimental results, future direction in searching for more $\\eta$--mesic nuclei is suggested.

  12. Exotic nuclei: production, properties and specificity

    Energy Technology Data Exchange (ETDEWEB)

    Van Duppen, Piet [Inst. voor Kern- en Stralingsfysika, Leuven Univ., Celestijnenlaan 200D, B-3001 Leuven (Belgium); Collaboration: La Direction des Sciences de la Matiere du CEA (FR); Le Fonds National de la Recherche Scientifique de Belgique (BE)

    1998-12-31

    In this paper we will put the production of energetic radioactive ion beams of exotic nuclei in perspective and describe the two complementary production processes that are used nowadays: Isotope Separation On-Line (ISOL) followed by post-acceleration, and In-Flight Separation (IFS). After a general description of the process we will focus on recent technical developments in the field. In the subsequent section we give some `typical` examples of physics cases that are addressed with exotic beams. The examples are chosen not only because their physics importance but also to demonstrate the complementary aspects in the production process and the detection systems. This overview will not be complete and the reader is referred to literature for further information, nor is the lecture intended to give an overview of all the efforts that are taking place in the field by mentioning every project separately. (author) 50 refs., 11 figs., 1 tab.

  13. Dielectronic Recombination In Active Galactic Nuclei

    Science.gov (United States)

    Lukić, D.; Savin, D. W.; Schnell, M.; Brandau, C.; Schmidt, E.; Schippers, S.; Müller, A.; Lestinsky, M.; Sprenger, F.; Wolf, A.; Altun, Z.; Badnell, N. R.

    2006-05-01

    Recent X-ray satelitte observations of active galactic nuclei point out shortcomings in our understanding of low temperature dielectronic recombination (DR) for iron M- shell ions. In order to resolve this issue and to provide reliable iron M-shell DR data for modeling astrophysical plasmas, we are carrying out a series of laboratory measurements using the heavy-ion Test Storage Ring at the Max- Plank-Institute for Nuclear Physics in Heidelberg, Germany. Storage rings are currently the only laboratory method capable of studying low temperature DR. We use our results to produce experimentally- derived DR rate coefficients. We are also providing our data to atomic theorist to benchmark their DR calculations. Here we will report our recent DR results for selected Fe M-shell ions. At temperatures where these ions are predicted to form in photoionized gas, we find a significant discrepancy between our experimental results and previously recommended DR rate coefficients.

  14. Production of Polarized Vector Mesons off Nuclei

    CERN Document Server

    Kopeliovich, B Z; Schmidt, I; Schmidt, Ivan

    2007-01-01

    Using the light-cone QCD dipole formalism we investigate manifestations of color transparency (CT) and coherence length (CL) effects in electroproduction of longitudinally (L) and transversally (T) polarized vector mesons. Motivated by forthcoming data from the HERMES experiment we predict both the A and Q^2 dependence of the L/T- ratios, for rho^0 mesons produced coherently and incoherently off nuclei. For an incoherent reaction the CT and CL effects add up and result in a monotonic A dependence of the L/T-ratio at different values of Q^2. On the contrary, for a coherent process the contraction of the CL with Q^2 causes an effect opposite to that of CT and we expect quite a nontrivial A dependence, especially at Q^2 >> m_V^2.

  15. Ground State Properties of Neutron Magic Nuclei

    CERN Document Server

    Saxena, G

    2016-01-01

    A systematic study of the ground state properties of the entire chains of even even neutron magic nuclei represented by isotones of traditional neutron magic numbers N = 8, 20, 40, 50, 82 and 126 has been carried out using relativistic mean field (rmf) plus Bardeen Cooper Schrieffer (BCS) approach. Our present investigation includes deformation, binding energy, two proton separation energy, single particle energy, rms radii along with proton and neutron density profiles, etc. Several of these results are compared with the results calculated using non relativistic approach (Skyrme Hartree Fock method) along with available experimental data and indeed they are found with excellent agreement. In addition, the possible locations of the proton and neutron drip lines, the (Z,N) values for the new shell closures, disappearance of traditional shell closures as suggested by the detailed analyzes of results are also discussed in detail.

  16. The Doubling of Stellar Black Hole Nuclei

    CERN Document Server

    Kazandjian, Mher V

    2012-01-01

    It is strongly believed that Andromeda's double nucleus signals a disk of stars revolving around its central super-massive black hole on eccentric Keplerian orbits with nearly aligned apsides. A self-consistent stellar dynamical origin for such apparently long-lived alignment has so far been lacking, with indications that cluster self-gravity is capable of sustaining such lopsided configurations if and when stimulated by external perturbations. Here, we present results of N-body simulations which show unstable counter-rotating stellar clusters around super-massive black holes saturating into uniformly precessing lopsided nuclei. The double nucleus in our featured experiment decomposes naturally into a thick eccentric disk of apo-apse aligned stars which is embedded in a lighter triaxial cluster. The eccentric disk reproduces key features of Keplerian disk models of Andromeda's double nucleus; the triaxial cluster has a distinctive kinematic signature which is evident in HST observations of Andromeda's double ...

  17. Momentum distribution of N$^*$ in nuclei

    CERN Document Server

    Kelkar, N G

    2016-01-01

    Due to its dominance in the low energy eta-nucleon interaction, the S11 N$^*$(1535) resonance enters as an important ingredient in the analyses of experiments aimed at finding evidence for the existence of eta-mesic nuclei. The static properties of the resonance get modified inside the nucleus and its momentum distribution is used in deciding these properties as well as the kinematics in the analyses. Here we show that given the possibility for the existence of an N$^*$-$^3$He quasibound state, the relative momentum distribution of an N$^*$ and $^3$He inside such a $^4$He is narrower than that of neutron-$^3$He in $^4$He. Results for the N$^*$-$^{24}$Mg system are also presented. The present exploratory work could be useful in motivating searches of exotic N$^*$-nucleus quasibound states as well as in performing analyses of eta meson production data.

  18. ``Missing'' cloud condensation nuclei in peat smoke

    Science.gov (United States)

    Dusek, U.; Frank, G. P.; Helas, G.; Iinuma, Y.; Zeromskiene, K.; Gwaze, P.; Hennig, T.; Massling, A.; Schmid, O.; Herrmann, H.; Wiedensohler, A.; Andreae, M. O.

    2005-06-01

    We characterized particulate emissions from vegetation fires by burning Indonesian and German peat and other biomass fuels in a controlled laboratory setting. By measuring cloud condensation nuclei (CCN) both as a function of particle diameter (dp) and supersaturation (S), we discovered particles in peat smoke that were not activated to cloud droplets at high S (1.6%). These hydrophobic particles were present predominantly in the size range of dp > 200 nm, where typical wood burning particles are activated at S < 0.3%. Ambient measurements during the 1997 Indonesian peat fires suggested that peat smoke particles are highly soluble and therefore efficient CCN. Our CCN measurements performed on fresh smoke from peat samples of the same area suggest that these Indonesian smoke particles probably acquired soluble material through chemical processing in the atmosphere. Freshly emitted peat smoke particles are at least partially not very efficient CCN.

  19. Dynamical effects in fusion with exotic nuclei

    CERN Document Server

    Vo-Phuoc, K; Simpson, E C

    2016-01-01

    [Background] Reactions with stable beams have demonstrated a strong interplay between nuclear structure and fusion. Exotic beam facilities open new perspectives to understand the impact of neutron skin, large isospin, and weak binding energies on fusion. Microscopic theories of fusion are required to guide future experiments. [Purpose] To investigate new effects of exotic structures and dynamics in near-barrier fusion with exotic nuclei. [Method] Microscopic approaches based on the Hartree-Fock (HF) mean-field theory are used for studying fusion barriers in $^{40-54}$Ca+$^{116}$Sn reactions for even isotopes. Bare potential barriers are obtained assuming frozen HF ground-state densities. Dynamical effects on the barrier are accounted for in time-dependent Hartree-Fock (TDHF) calculations of the collisions. Vibrational couplings are studied in the coupled-channel framework and near-barrier nucleon transfer is investigated with TDHF calculations. [Results] The development of a neutron skin in exotic calcium iso...

  20. Parity nonconservation in /sup 19/F nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Elsener, K.; Gruebler, W.; Koenig, V.; Schmelzbach, P.A.; Ulbricht, J.; Vuaridel, B.; Singy, D.; Forstner, C.; Zhang, W.Z.

    1987-01-12

    The parity nonconserving asymmetry A/sub ..gamma../ in the decay of polarized /sup 19/F/sup */(110 keV) nuclei has been measured. A value of A/sub ..gamma../=-(6.83 +- 2.11) x 10/sup -5/ (total error) was found. Systematic errors are extensively investigated and found to be small. The absolute normalization is given by the /sup 19/F/sup */ polarization, which is found to be rho/sub F/=-0.52 +- 0.08 in a separate experiment, using a calibrated Compton polarimeter. The new result A/sub ..gamma../(/sup 19/F) is compared to earlier experiments and recent theoretical calculations. From an analysis including /sup 18/F and /sup 21/Ne results, constraints on the weak meson-nucleon coupling constants f/sub ..pi../ and h/sub rho//sup 0/ are deduced. Agreement with calculations based on the standard electroweak theory and QCD is found.

  1. Clusters in neutron-rich light nuclei

    Directory of Open Access Journals (Sweden)

    Jelavić Malenica D.

    2016-01-01

    Full Text Available Due to their high selectivity, transfer and sequential decay reactions are powerful tools for studies of both single particle (nucleon and cluster states in light nuclei. Their use is particularly simple for investigations of α-particle clustering (because α-particle has Jπ=0+, which simplifies spin and parity assignments to observed cluster states, but they are also easily applicable to other types of clustering. Recent results on clustering in neutron-rich isotopes of beryllium, boron and carbon obtained measuring the 10B+10B reactions (at 50 and 72 MeV are presented. The highly efficient and segmented detector systems used, built from 4 Double Sided Silicon Strip Detectors (DSSSD allowed detection of double and multiple coincidences and, in that way, studies of states populated in transfer reactions, as well as their sequential decay.

  2. Structural features of protein folding nuclei.

    Science.gov (United States)

    Garbuzynskiy, S O; Kondratova, M S

    2008-03-05

    A crucial event of protein folding is the formation of a folding nucleus. We demonstrate the presence of a considerable coincidence between the location of folding nuclei and the location of so-called "root structural motifs", which have unique overall folds and handedness. In the case of proteins with a single root structural motif, the involvement in the formation of a folding nucleus is in average significantly higher for amino acids residues that are in root structural motifs, compared to residues in other parts of the protein. The tests carried out revealed that the observed difference is statistically reliable. Thus, a structural feature that corresponds to the protein folding nucleus is now found.

  3. Personal cooling apparatus and method

    Energy Technology Data Exchange (ETDEWEB)

    Siman-Tov, Moshe (Knoxville, TN); Crabtree, Jerry Allen (Knoxville, TN)

    2001-01-01

    A portable lightweight cooling apparatus for cooling a human body is disclosed, having a channeled sheet which absorbs sweat and/or evaporative liquid, a layer of highly conductive fibers adjacent the channeled sheet; and, an air-moving device for moving air through the channeled sheet, wherein the layer of fibers redistributes heat uniformly across the object being cooled, while the air moving within the channeled sheet evaporates sweat and/or other evaporative liquid, absorbs evaporated moisture and the uniformly distributed heat generated by the human body, and discharges them into the environment. Also disclosed is a method for removing heat generated by the human body, comprising the steps of providing a garment to be placed in thermal communication with the body; placing a layer of highly conductive fibers within the garment adjacent the body for uniformly distributing the heat generated by the body; attaching an air-moving device in communication with the garment for forcing air into the garment; removably positioning an exchangeable heat sink in communication with the air-moving device for cooling the air prior to the air entering the garment; and, equipping the garment with a channeled sheet in communication with the air-moving device so that air can be directed into the channeled sheet and adjacent the layer of fibers to expell heat and moisture from the body by the air being directed out of the channeled sheet and into the environment. The cooling system may be configured to operate in both sealed and unsealed garments.

  4. Oxygen Absorption in Cooling Flows.

    Science.gov (United States)

    Buote

    2000-04-01

    The inhomogeneous cooling flow scenario predicts the existence of large quantities of gas in massive elliptical galaxies, groups, and clusters that have cooled and dropped out of the flow. Using spatially resolved, deprojected X-ray spectra from the ROSAT PSPC, we have detected strong absorption over energies approximately 0.4-0.8 keV intrinsic to the central approximately 1&arcmin; of the galaxy NGC 1399, the group NGC 5044, and the cluster A1795. These systems have among the largest nearby cooling flows in their respective classes and low Galactic columns. Since no excess absorption is indicated for energies below approximately 0.4 keV, the most reasonable model for the absorber is warm, collisionally ionized gas with T=105-106 K in which ionized states of oxygen provide most of the absorption. Attributing the absorption only to ionized gas reconciles the large columns of cold H and He inferred from Einstein and ASCA with the lack of such columns inferred from ROSAT and also is consistent with the negligible atomic and molecular H inferred from H i and CO observations of cooling flows. The prediction of warm ionized gas as the product of mass dropout in these and other cooling flows can be verified by Chandra and X-Ray Multimirror Mission.

  5. Axion Cooling of Neutron Stars

    CERN Document Server

    Sedrakian, Armen

    2015-01-01

    Cooling simulations of neutron stars and their comparison with the data from thermally emitting X-ray sources puts constraints on the properties of axions, and by extension of any light pseudo-scalar dark matter particles, whose existence has been postulated to solve the strong-CP problem of QCD. We incorporate the axion emission by pair-breaking and formation processes by $S$- and $P$-wave nucleonic condensates in a benchmark code for cooling simulations as well as provide fit formulae for the rates of these processes. Axion cooling of neutron stars has been simulated for 24 models covering the mass range 1 to 1.8 solar masses, featuring non-accreted iron and accreted light element envelopes, and a range of nucleon-axion coupling. The models are based on an equation state predicting conservative physics of superdense nuclear matter that does not allow for onset of fast cooling processes induced by phase transitions to non-nucleonic forms of matter or high proton concentration. The cooling tracks in the tempe...

  6. Oxidation stability of ice nuclei from plants

    Science.gov (United States)

    Felgitsch, Laura; Häusler, Thomas; Grothe, Hinrich

    2017-04-01

    Heterogeneous ice nucleation is an important process in cloud formation and therefore has direct influence on the radiation budget of the Earth. Biological ice nuclei (IN) are highly abundant in nature. Many plants have been found to produce IN. These IN are of special interest, since several have been found to be in a nano-particular/macromolecular size range (Pummer et al. 2015, Felgitsch et al. 2016). Particles of such a small size should show a high lifespan in the atmosphere. Further the substances can easily be attached to mineral dusts. Very little is known about the atmospheric fate of plant derived ice nuclei (IN) in case they become airborne. While they inherit the possibility to influence ice cloud formation, this property depends highly on the expected lifespan of the substance and of its ice nucleation activity in the atmosphere. For our experiment we exposed plant IN derived from black currant (berry juice) and birch (pollen washing water) to high concentrations of highly oxidative substances typically present in the atmosphere. The exposure lasted several hours and allowed us to monitor the changes in ice nucleation activity. Our results suggest a high stability towards oxidation leading to a high atmospheric life span of the ice nucleation activity if airborne. Pummer, B.G., Budke, C., Augustin-Bauditz, S., Niedermeier, D., Felgitsch, L., Kampf, C.J., Huber, R.G., Liedl, K.R., Loerting, T., Moschen, T., Schauperl, M., Tollinger, M., Morris, C.E., Wex, H., Grothe, H., Pöschl, U., Koop, T., and Fröhlich-Nowoisky, J.: Ice nucleation by water-soluble macromolecules, Atmos. Chem. Phys., 15, 4077-4091, 2015. Felgitsch , L., Bichler, M., Häusler, T., Hitzenberger, R., and Grothe, H.: Heterogeneous freezing of water triggered by berry juices from perenneal plants, submitted, 2016.

  7. Dynamical effects in fusion with exotic nuclei

    Science.gov (United States)

    Vo-Phuoc, K.; Simenel, C.; Simpson, E. C.

    2016-08-01

    Background: Reactions with stable beams have demonstrated strong interplay between nuclear structure and fusion. Exotic beam facilities open new perspectives to understand the impact of neutron skin, large isospin, and weak binding energies on fusion. Microscopic theories of fusion are required to guide future experiments. Purpose: To investigate new effects of exotic structures and dynamics in near-barrier fusion with exotic nuclei. Method: Microscopic approaches based on the Hartree-Fock (HF) mean-field theory are used for studying fusion barriers in -54Ca40+116Sn reactions for even isotopes. Bare potential barriers are obtained assuming frozen HF ground-state densities. Dynamical effects on the barrier are accounted for in time-dependent Hartree-Fock (TDHF) calculations of the collisions. Vibrational couplings are studied in the coupled-channel framework and near-barrier nucleon transfer is investigated with TDHF calculations. Results: The development of a neutron skin in exotic calcium isotopes strongly lowers the bare potential barrier. However, this static effect is not apparent when dynamical effects are included. On the contrary, a fusion hindrance is observed in TDHF calculations with the most neutron-rich calcium isotopes which cannot be explained by vibrational couplings. Transfer reactions are also important in these systems due to charge equilibration processes. Conclusions: Despite its impact on the bare potential, the neutron skin is not seen as playing an important role in the fusion dynamics. However, the charge transfer with exotic projectiles could lead to an increase of the Coulomb repulsion between the fragments, suppressing fusion. The effects of transfer and dissipative mechanisms on fusion with exotic nuclei deserve further studies.

  8. Feldspar minerals as efficient deposition ice nuclei

    Directory of Open Access Journals (Sweden)

    J. D. Yakobi-Hancock

    2013-06-01

    Full Text Available Mineral dusts are well known to be efficient ice nuclei, where the source of this efficiency has typically been attributed to the presence of clay minerals such as illite and kaolinite. However, the ice nucleating abilities of the more minor mineralogical components have not been as extensively examined. As a result, the deposition ice nucleation abilities of 24 atmospherically-relevant mineral samples have been studied, using a continuous flow diffusion chamber at −40.0 ± 0.3 °C. The same particle size (200 nm and particle preparation procedure were used throughout. The ice nucleation behaviour of the pure minerals is compared to that of complex mixtures, such as Arizona Test Dust (ATD and Mojave Desert Dust (MDD, and to lead iodide, which has been previously proposed for cloud seeding. Lead iodide was the most efficient ice nucleus (IN, requiring a critical relative humidity with respect to ice (RHi of 122.0 ± 2.0% to activate 0.1% of the particles. MDD (RHi 126.3 ± 3.4% and ATD (RHi 129.5 ± 5.1% have lower but comparable activity. From a set of clay minerals (kaolinite, illite, montmorillonite, non-clay minerals (e.g. hematite, magnetite, calcite, cerussite, quartz, and feldspar minerals (orthoclase, plagioclase present in the atmospheric dusts it was found that the feldspar minerals (particularly orthoclase, and not the clays, were the most efficient ice nuclei. Orthoclase and plagioclase were found to have critical RHi values of 127.1 ± 6.3% and 136.2 ± 1.3%, respectively. The presence of feldspars (specifically orthoclase may play a significant role in the IN behaviour of mineral dusts despite their lower percentage in composition relative to clay minerals.

  9. Decay of Hot Nuclei at Low Spins Produced by Antiproton-Annihilation in Heavy Nuclei

    CERN Multimedia

    2002-01-01

    % PS208 \\\\ \\\\ The objective of the experiment is to study (i) the thermal excitation energy distribution of antiproton-induced reactions in heavy nuclei and (ii) the decay properties of hot nuclei at low spins via evaporation, multifragmentation and fission as a function of excitation energy. The experimental set-up consists of 4-$\\pi$ detectors: the Berlin Neutron Ball~(BNB) which is a spherical shell of gadolinium-loaded scintillator liquid with an inner and outer diameter of 40 and 160~cm, respectively. This detector counts the number of evaporated neutrons in each reaction. Inside BNB there is a 4-$\\pi$ silicon ball~(BSIB) with a diameter of 20~cm consisting of 162 detectors which measure energy and multiplicity of all emitted charged nuclear particles. The particles are identified via time of flight, energy and pulse shape correlations.

  10. Nuclei in motion: movement and positioning of plant nuclei in development, signaling, symbiosis and disease.

    Directory of Open Access Journals (Sweden)

    Anna Hare Newman Griffis

    2014-04-01

    Full Text Available While textbook figures imply nuclei as resting spheres at the center of idealized cells, this picture fits few real situations. Plant nuclei come in many shapes and sizes, and can be actively transported within the cell. In several contexts, this nuclear movement is tightly coupled to a developmental program, the response to an abiotic signal, or a cellular reprogramming during either mutualistic or parasitic plant-microbe interactions. While many such phenomena have been observed and carefully described, the underlying molecular mechanism and the functional significance of the nuclear movement are typically unknown. Here, we survey recent as well as older literature to provide a concise starting point for applying contemporary molecular, genetic and biochemical approaches to this fascinating, yet poorly understood phenomenon.

  11. Airborne measurements of condensation nuclei and cloud condensation nuclei above the alpine foothills

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, B. [Inst. for Meteorology and Geophysics, Univ. of Frankfurt (Germany); Georgii, H.W. [Inst. for Meteorology and Geophysics, Univ. of Frankfurt (Germany)

    1994-11-01

    During the Cloud Experiment OberPfaffenhofen And TRAnsport (CLEOPATRA) in the summer 1992 airborne measurements of cloud condensation nuclei (CCN) and concentrations of condensation nuclei (CN) or total particle concentration have been determined. Flights were made in convective as well as in stratiform clouds. Enhancement of particle concentrations in the vicinity of clouds was observed in some but not all cases. Conditions pertaining to enhanced concentrations are examined. (orig.) [Deutsch] Im Sommer 1992 wurden im Rahmen des CLoud Experiment OberPfaffenhofen And TRAnsport (CLEOPATRA) Flugzeugmessungen von Wolkenkondensationskernen (CCN) und Kondensationskernen (CN) durchgefuehrt. Bei Fluegen in konvektiven und stratiformen Wolken wurde ein Anstieg von Partikeln im Wolkenrandbereich gemessen. Dieser Anstieg konnte allerdings nicht in allen Faellen beobachtet werden und war abhaengig von den Umgebungsbedingungen. (orig.)

  12. Analysis of Orientation Relations Between Deformed Grains and Recrystallization Nuclei

    DEFF Research Database (Denmark)

    West, Stine S.; Winther, Grethe; Juul Jensen, Dorte

    2011-01-01

    Nucleation in 30 pct rolled high-purity aluminum samples was investigated by the electron backscattering pattern method before and after annealing. A total of 29 nuclei including two twins were observed, and approximately one third of these nuclei had orientations not detected in the deformed sta...

  13. Comparing and contrasting nuclei and cold atomic gases

    DEFF Research Database (Denmark)

    Zinner, Nikolaj Thomas; Jensen, Aksel Stenholm

    2013-01-01

    , interactions, and relevant length and energy scales of cold atoms and nuclei. Next we address some attempts in nuclear physics to transfer the concepts of condensates in nuclei that can in principle be built from bosonic alpha-particle constituents. We also consider Efimov physics, a prime example of nuclear...

  14. Origin of light nuclei in near earth orbit

    CERN Document Server

    Derome, L

    2001-01-01

    The possible sources of light nuclei populations observed recently below the geomagnetic cutoff by the AMS experiment are discussed in terms of nuclear processes: fragmentation of the incoming flux of cosmic helium on atmospheric nuclei, and nuclear coalescence from proton and helium induced reactions. Results of simulations for deuterium, tritium, helium 3 and 4, are presented.

  15. Study of cosmic ray nuclei detection by an image calorimeter

    Energy Technology Data Exchange (ETDEWEB)

    Casolino, M.; Sparvoli, R.; Morselli, A.; Picozza, P. [Rome Univ. `Tor Vergata` (Italy)]|[INFN, Sezione Univ. `Tor Vergata` Rome (Italy); Ozerov, Yu.V.; Zemskov, V.M.; Zverev, V.G.; Galper, A.M. [Moscow Engineering Physics Institute, Moscow (Russian Federation); Carlson, P. [Royal Institute of Technology, Stockholm (Sweden); Fuglesang, C. [ESA-EAC, Cologne (Germany)

    1995-09-01

    It is shown that a cosmic gamma-ray telescope made of a multilayer silicon tracker and a imaging CsI calorimeter, is capable of identifying cosmic ray nuclei. The telescope charge resolution is estimated around 4% independently of charge. Simulation methods are used to determine the telescope properties for nuclei detection.

  16. Investigation of irradiated PA1010 containing heterogeneous nuclei

    Science.gov (United States)

    Baozhong, Li; Lihua, Zhang; Yayan, Liu; Qi, Liang

    1996-09-01

    This paper deals with radiation effects on PAI010 containing heterogeneous nuclei (Nd203). With the help of DSC, WARD and ESR techniques, the change in the crystallinity and the perfection of the crystal of irradiated PA1010 containing heterogeneous nuclei were studied.

  17. Cool Stars and Space Weather

    CERN Document Server

    Vidotto, A A; Cameron, A C; Morin, J; Villadsen, J; Saar, S; Alvarado, J; Cohen, O; Holzwarth, V; Poppenhaeger, K; Reville, V

    2014-01-01

    Stellar flares, winds and coronal mass ejections form the space weather. They are signatures of the magnetic activity of cool stars and, since activity varies with age, mass and rotation, the space weather that extra-solar planets experience can be very different from the one encountered by the solar system planets. How do stellar activity and magnetism influence the space weather of exoplanets orbiting main-sequence stars? How do the environments surrounding exoplanets differ from those around the planets in our own solar system? How can the detailed knowledge acquired by the solar system community be applied in exoplanetary systems? How does space weather affect habitability? These were questions that were addressed in the splinter session "Cool stars and Space Weather", that took place on 9 Jun 2014, during the Cool Stars 18 meeting. In this paper, we present a summary of the contributions made to this session.

  18. Quench cooling under reduced gravity

    CERN Document Server

    Chatain, D; Nikolayev, V S; Beysens, D

    2013-01-01

    We report the quench cooling experiments performed with liquid O2 under different levels of gravity simulated with the magnetic gravity compensation. A copper disk is quenched from 270K to 90K. It is found that the cooling time in microgravity is very long in comparison with any other gravity level. This phenomenon is explained by the isolation effect of the gas surrounding the disk. The liquid subcooling is shown to drastically improuve the heat exchange thus reducing the cooling time (about 20 times). The effect of subcooling on the heat transfer is analyzed at different gravity levels. It is shown that such type of experiments cannot be used for the analysis of the critical heat flux (CHF) of the boiling crisis. The minimum heat flux (MHF) of boiling is analyzed instead.

  19. Metal complexation inhibits the effect of oxalic acid in aerosols as cloud condensation nuclei (CCN

    Directory of Open Access Journals (Sweden)

    T. Furukawa

    2010-11-01

    Full Text Available Atmospheric aerosols have both a direct and an indirect cooling effect that influences the radiative balance at the Earth's surface. It has been estimated that the degree of cooling is large enough to cancel the warming effect of carbon dioxide. Among the cooling factors, secondary organic aerosols (SOA play a key role in the solar radiation balance in the troposphere as SOA can act as cloud condensation nuclei (CCN and extend the lifespan of clouds because of their high hygroscopic and water soluble nature. Oxalic acid is one of the major components of SOA, and is produced via several formation pathways in the atmosphere. However, it is not certain whether oxalic acid exists as free oxalic acid or as metal oxalate complexes in aerosols, although there is a marked difference in their solubility in water and their hygroscopicity. We employed X-ray absorption fine structure spectroscopy to characterize the calcium (Ca and zinc (Zn in aerosols collected at Tsukuba in Japan with fractionation based on particle size using an impactor aerosol sampler. It was shown that 10–60% and 20–100% of the total Ca and Zn in the finer particles (<2.1 μm were present as Ca and Zn oxalate complexes, respectively. Oxalic acid can act as CCN because of its hygroscopic properties, while metal complexes are not hygroscopic, and so cannot be CCN. Based on the concentration of noncomplexed and metal-complexed oxalate species, we found that most of the oxalic acid is present as metal oxalate complexes in the aerosols, suggesting that oxalic acid does not act as CCN in the atmosphere. Similar results are expected for other dicarboxylic acids, such as malonic and succinic acids. Thus, it is possible that the cooling effect of organic aerosols assumed in various climate modeling studies is overestimated because of the lack of information on metal oxalate complexes in aerosols.

  20. The effect of pre-cooling intensity on cooling efficiency and exercise performance

    NARCIS (Netherlands)

    Bogerd, N.; Perret, C.; Bogerd, C.P.; Rossi, R.M.; Daanen, H.A.M.

    2010-01-01

    Although pre-cooling is known to enhance exercise performance, the optimal cooling intensity is unknown. We hypothesized that mild cooling opposed to strong cooling circumvents skin vasoconstriction and thermogenesis, and thus improves cooling efficiency reflected in improved time to exhaustion. Eig