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1. First evidence of low energy enhancement in Ge isotopes

Author

Renstrøm T., Nyhus H.-T., Utsunomiya H., Larsen A. C., Siem S., Guttormsen M., Filipescu D. M., Gheorghe I., Goriely S., Bernstein L. A., Bleuel D. L., Glodariu T., Görgen A., Hagen T. W., Lui Y.-W., Negi D., Ruud I. E., Şahin E., Schwengner R., Shima T., Takahisa K., Tesileanu O., Tornyi T. G., Tveten G. M., and Wiedeking M.

Subjects
Physics, QC1-999
Abstract

The γ-strength functions and level densities of 73,74Ge have been extracted from particle-γ coincidence data using the Oslo method. In addition the γ-strength function of 74Ge above the neutron separation threshold, Sn = 10.196 MeV has been extracted from photoneutron measurements. When combined, these two experiments give a γ-strength function covering the energy range of ∼1-13 MeV for 74Ge. This thorough investigation of 74Ge is a part of an international campaign to study the previously reported low energy enhancement in this mass region in the γ-strength function from ∼3MeV towards lower γ energies. The obtained data show that both 73,74Ge display an increase in strength at low γ energies.

Published
2015
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2. Low-energy enhancement and fluctuations of $\gamma$-ray strength functions in $^{56,57}$Fe: test of the Brink-Axel hypothesis

Author

Larsen, A. C., Guttormsen, M., Blasi, N., Bracco, A., Camera, F., Campo, L. Crespo, Eriksen, T. K., Görgen, A., Hagen, T. W., Ingeberg, V. W., Kheswa, B. V., Leoni, S., Midtbø, J. E., Million, B., Nyhus, H. T., Renstrøm, T., Rose, S. J., Ruud, I. E., Siem, S., Tornyi, T. G., Tveten, G. M., Voinov, A. V., Wiedeking, M., and Zeiser, F.

Subjects
Nuclear Experiment
Abstract

Nuclear level densities and $\gamma$-ray strength functions of $^{56,57}$Fe have been extracted from proton-$\gamma$ coincidences. A low-energy enhancement in the $\gamma$-ray strength functions up to a factor of 30 over common theoretical E1 models is confirmed. Angular distributions of the low-energy enhancement in $^{57}$Fe indicate its dipole nature, in agreement with findings for $^{56}$Fe. The high statistics and the excellent energy resolution of the large-volume LaBr$_{3}$(Ce) detectors allowed for a thorough analysis of $\gamma$ strength as function of excitation energy. Taking into account the presence of strong Porter-Thomas fluctuations, there is no indication of any significant excitation-energy dependence in the $\gamma$-ray strength function, in support of the generalized Brink-Axel hypothesis., Comment: 24 pages, 17 figures, accepted for publication in J. Phys. G: Nucl. Phys; Special Issue

Published
2016
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3. Low-energy enhancement in the \gamma-ray strength functions of $^{73,74}$Ge

Author

Renstrøm, T., Nyhus, H. -T., Utsumoniya, H., Schwengner, R., Goriely, S., Larsen, A. C., Filipescu, D. M., Gheorghe, I., Bernstein, L. A., Bleuel, D. L., Glodariu, T., Görgen, A., Guttormsen, M., Hagen, T. W., Kheswa, B. V., Lui, Y. -W ., Negi, D., Ruud, I. E., Shima, T., Siem, S., Takahisa, K., Tesileanu, O., Tornyi, T. G., Tveten, G. M., and Wiedeking, M.

Subjects
Nuclear Experiment
Abstract

The $\gamma$-ray strength functions and level densities of $^{73,74}$Ge have been extracted up to the neutron separation energy S$_n$ from particle-$\gamma$ coincidence data using the Oslo method. Moreover, the $\gamma$-ray strength function of $^{74}$Ge above S$_n$ has been determined from photo-neutron measurements, hence these two experiments cover the range of E$_\gamma \approx$ 1-13 MeV for $^{74}$Ge. The obtained data show that both $^{73,74}$Ge display an increase in strength at low $\gamma$ energies. The experimental $\gamma$-ray strength functions are compared with $M1$ strength functions deduced from average $B(M1)$ values calculated within the shell model for a large number of transitions. The observed low-energy enhancements in $^{73,74}$Ge are adopted in the calculations of the $^{72,73}$Ge(n,$\gamma$) cross sections, where there are no direct experimental data. Calculated reaction rates for more neutron-rich germanium isotopes are shown to be strongly dependent on the presence of the low-energy enhancement.

Published
2015
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4. Evidence for dipole nature of the low-energy $\gamma$ enhancement in $^{56}$Fe

Author

Larsen, A. C., Blasi, N., Bracco, A., Camera, F., Eriksen, T. K., Görgen, A., Guttormsen, M., Hagen, T. W., Leoni, S., Million, B., Nyhus, H. T., Renstrøm, T., Rose, S. J., Ruud, I. E., Siem, S., Tornyi, T., Tveten, G. M., Voinov, A. V., and Wiedeking, M.

Subjects
Nuclear Experiment
Abstract

The $\gamma$-ray strength function of $^{56}$Fe has been measured from proton-$\gamma$ coincidences for excitation energies up to $\approx 11$ MeV. The low-energy enhancement in the $\gamma$-ray strength function, which was first discovered in the ($^3$He,$\alpha\gamma$)$^{56}$Fe reaction, is confirmed with the ($p,p^\prime\gamma$)$^{56}$Fe experiment reported here. Angular distributions of the $\gamma$ rays give for the first time evidence that the enhancement is dominated by dipole transitions., Comment: 5 pages, 4 figures. Version accepted for publication in Phys. Rev. Letters

Published
2013
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5. Transitional $\gamma$ strength in Cd isotopes

Author

Larsen, A. C., Ruud, I. E., Bürger, A., Goriely, S., Guttormsen, M., Görgen, A., Hagen, T. W., Harissopulos, S., Nyhus, H. T., Renstrøm, T., Schiller, A., Siem, S., Tveten, G. M., Voinov, A. V., and Wiedeking, M.

Subjects
Nuclear Experiment
Abstract

The level densities and $\gamma$-ray strength functions of $^{105,106,111,112}$Cd have been extracted from particle-$\gamma$ coincidence data using the Oslo method. The level densities are in very good agreement with known levels at low excitation energy. The $\gamma$-ray strength functions display no strong enhancement for low $\gamma$ energies. However, more low-energy strength is apparent for $^{105,106}$Cd than for $^{111,112}$Cd. For $\gamma$ energies above $\approx$ 4 MeV, there is evidence for some extra strength, similar to what has been previously observed for the Sn isotopes. The origin of this extra strength is unclear; it might be due to $E1$ and $M1$ transitions originating from neutron skin oscillations or the spin-flip resonance, respectively., Comment: 10 pages, 11 figures

Published
2013
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6. Low-energy enhancement in the gamma-ray strength functions of 73,74Ge

Author

Renstrøm, T., Nyhus, H. -T., Utsumoniya, H., Schwengner, R., Goriely, S., Larsen, A. C., Filipescu, D. M., Gheorghe, I., Bernstein, L. A., Bleuel, D. L., Glodariu, T., Görgen, A., Guttormsen, M., Hagen, T. W., Kheswa, B. V., Lui, Y. -W ., Negi, D., Ruud, I. E., Shima, T., Siem, S., Takahisa, K., Tesileanu, O., Tornyi, T. G., Tveten, G. M., and Wiedeking, M.

Subjects
level densities, Astrophysics::High Energy Astrophysical Phenomena, Nuclear structure, Nuclear Experiment, nuclear reactions, strength functiopns
Abstract

The $\gamma$-ray strength functions and level densities of $^{73,74}$Ge have been extracted up to the neutron separation energy S$_n$ from particle-$\gamma$ coincidence data using the Oslo method. Moreover, the $\gamma$-ray strength function of $^{74}$Ge above S$_n$ has been determined from photo-neutron measurements, hence these two experiments cover the range of E$_\gamma \approx$ 1-13 MeV for $^{74}$Ge. The obtained data show that both $^{73,74}$Ge display an increase in strength at low $\gamma$ energies. The experimental $\gamma$-ray strength functions are compared with $M1$ strength functions deduced from average $B(M1)$ values calculated within the shell model for a large number of transitions. The observed low-energy enhancements in $^{73,74}$Ge are adopted in the calculations of the $^{72,73}$Ge(n,$\gamma$) cross sections, where there are no direct experimental data. Calculated reaction rates for more neutron-rich germanium isotopes are shown to be strongly dependent on the presence of the low-energy enhancement.

Published
2016

7. Low-energy enhancement in the γ-ray strength functions of 73,74Ge

Author

Renstrøm, Therese, Nyhus, H.-T., Utsunomiya, Hiroaki, Schwengner, R., Goriely, S., Larsen, Ann-Cecilie, Filipescu, D. M., Gheorghe, I., Bernstein, L. A., Bleuel, D. L., Glodariu, T., Görgen, A., Guttormsen, Magne, Hagen, Trine Wiborg, Kheswa, B. V., Lui, Y. W., Negi, D., Ruud, I. E., Shima, T., Siem, Sunniva, Takahisa, K., Tesileanu, O., Tornyi, T. G., Tveten, Gry M., and Wiedeking, M.

Published
2016

8. Low-energy enhancement and fluctuations ofγ-ray strength functions in56,57Fe: test of the Brink–Axel hypothesis

Author

Larsen, A C, primary, Guttormsen, M, additional, Blasi, N, additional, Bracco, A, additional, Camera, F, additional, Campo, L Crespo, additional, Eriksen, T K, additional, Görgen, A, additional, Hagen, T W, additional, Ingeberg, V W, additional, Kheswa, B V, additional, Leoni, S, additional, Midtbø, J E, additional, Million, B, additional, Nyhus, H T, additional, Renstrøm, T, additional, Rose, S J, additional, Ruud, I E, additional, Siem, S, additional, Tornyi, T G, additional, Tveten, G M, additional, Voinov, A V, additional, Wiedeking, M, additional, and Zeiser, F, additional

Published
2017
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9. First evidence of low energy enhancement in Ge isotopes

Author

Renstrøm, Therese, Nyhus, Hilde Therese, Utsunomiya, Hiroaki, Larsen, Ann-Cecilie, Siem, Sunniva, Guttormsen, Magne, Filipescu, D.M., Gheorghe, I., Goriely, Stéphane, BA, Cheikh Oumar, Bleuel, D.L., Glodariu, T., Görgen, Andreas, Hagen, T.W., Lui, Yiu-Wing, Negi, D., Ruud, I. E., Sahin, E, Schwengner, Ronald, Shima, Tadashi, Takahisa, K., Tesileanu, O., Tornyi, T., Tveten, G. M., Wiedeking, M., Renstrøm, Therese, Nyhus, Hilde Therese, Utsunomiya, Hiroaki, Larsen, Ann-Cecilie, Siem, Sunniva, Guttormsen, Magne, Filipescu, D.M., Gheorghe, I., Goriely, Stéphane, BA, Cheikh Oumar, Bleuel, D.L., Glodariu, T., Görgen, Andreas, Hagen, T.W., Lui, Yiu-Wing, Negi, D., Ruud, I. E., Sahin, E, Schwengner, Ronald, Shima, Tadashi, Takahisa, K., Tesileanu, O., Tornyi, T., Tveten, G. M., and Wiedeking, M.

Abstract

info:eu-repo/semantics/published

Published
2015

10. Transitional gamma strength in Cd isotopes

Author

Larsen, A. C., Ruud, I. E., Bürger, A., Goriely, S., Guttormsen, M., Görgen, A., Hagen, T. W., Harissopulos, S., Nyhus, H. T., Renstrøm, T., Schiller, A., Siem, S., Tveten, G. M., Voinov, A. V., and Wiedeking, M.

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Nuclear Experiment, Physique atomique et nucléaire
Abstract

The level densities and $\gamma$-ray strength functions of $^{105,106,111,112}$Cd have been extracted from particle-$\gamma$ coincidence data using the Oslo method. The level densities are in very good agreement with known levels at low excitation energy. The $\gamma$-ray strength functions display no strong enhancement for low $\gamma$ energies. However, more low-energy strength is apparent for $^{105,106}$Cd than for $^{111,112}$Cd. For $\gamma$ energies above $\approx$ 4 MeV, there is evidence for some extra strength, similar to what has been previously observed for the Sn isotopes. The origin of this extra strength is unclear; it might be due to $E1$ and $M1$ transitions originating from neutron skin oscillations or the spin-flip resonance, respectively., Comment: 10 pages, 11 figures

Published
2013

11. Evidence for the Dipole Nature of the Low-Energy [Gamma] Enhancement in 56Fe

Author

Larsen, A. C., Blasi, N., Bracco, A., Camera, F., Eriksen, T. K., Görgen, A., Guttormsen, M., Hagen, T. W., Leoni, S., Million, B., Nyhus, H. T., Renstrøm, T., Rose, S. J., Ruud, I. E., Siem, S., Tornyi, Tamás Gábor, Tveten, G. M., Voinov, A. V., and Wiedeking, M.

Subjects
Természettudományok, Fizikai tudományok
Published
2013

12. Astrophysical reaction rates and the low-energy enhancement in the gamma-strength

Author

Larsen, Ann-Cecilie, Burger, A., Goriely, Stéphane, Guttormsen, Magne, Görgen, Andreas, Eriksen, T.K., Hagen, T.W., Harissopulos, Sotirios, Nyhus, Hilde Therese, Renstrom, T., Rose, S.J., Ruud, I. E., Schiller, Andreas, Siem, Sunniva, Tveten, G. M., Voinov, A., Larsen, Ann-Cecilie, Burger, A., Goriely, Stéphane, Guttormsen, Magne, Görgen, Andreas, Eriksen, T.K., Hagen, T.W., Harissopulos, Sotirios, Nyhus, Hilde Therese, Renstrom, T., Rose, S.J., Ruud, I. E., Schiller, Andreas, Siem, Sunniva, Tveten, G. M., and Voinov, A.

Abstract

An unexpected enhancement in the γ-strength function for Eγ < 3 MeV for Ti, Sc, V, Fe, and Mo nuclei close to the valley of stability has been discovered at the Oslo Cyclotron Laboratory. Provided that this enhance- ment is present also in very neutron-rich nuclei, it could give an increase in the neutron-capture rates up to two orders of magnitude. However, it is still an open question whether this structure persists when approaching the neutron drip line., info:eu-repo/semantics/published

Published
2013

13. Transitional gamma strength in Cd isotopes

Author

Larsen, André, Ruud, I. E., Burger, Arnold, Goriely, Stéphane, Guttormsen, Magne, Görgen, Andreas, Hagen, W. T., Harissopulos, Sotirios, Nyhus, Hilde Therese, Renstrom, T., Schiller, Andreas, Siem, Sunniva, Tveten, G. M., Voinov, A., Wiedeking, M., Larsen, André, Ruud, I. E., Burger, Arnold, Goriely, Stéphane, Guttormsen, Magne, Görgen, Andreas, Hagen, W. T., Harissopulos, Sotirios, Nyhus, Hilde Therese, Renstrom, T., Schiller, Andreas, Siem, Sunniva, Tveten, G. M., Voinov, A., and Wiedeking, M.

Abstract

info:eu-repo/semantics/published

Published
2013

14. Gamma‐ray strength functions and their relation to astrophysics

Author

Larsen, André, Goriely, Stéphane, Algin, E, Agvaanluvsan, Undraa, Burger, Arnold, Görgen, Andreas, Guttormsen, Magne, Hagen, W. T., Lonnroth, Tom, Mitchell, Gerardine, Nyhus, Hilde Therese, Rekstad, J. B., Renstrom, T., Rose, S. J., Ruud, I. E., Schiller, Andreas, Siem, Sunniva, Syed, N.U.H., Toft, H.K., Tveten, G. M., Voinov, A., Wikan, K., Larsen, André, Goriely, Stéphane, Algin, E, Agvaanluvsan, Undraa, Burger, Arnold, Görgen, Andreas, Guttormsen, Magne, Hagen, W. T., Lonnroth, Tom, Mitchell, Gerardine, Nyhus, Hilde Therese, Rekstad, J. B., Renstrom, T., Rose, S. J., Ruud, I. E., Schiller, Andreas, Siem, Sunniva, Syed, N.U.H., Toft, H.K., Tveten, G. M., Voinov, A., and Wikan, K.

Abstract

info:eu-repo/semantics/published

Published
2011

16. Low-energy enhancement of nuclear γ strength and its impact on astrophysical reaction rates

Author

Larsen A. C., Blasi N., Bracco A., Bürger A., Camera F., Eriksen T.K., Giacoppo F., Goriely S., Guttormsen M., Görgen A., Hagen T. W., Harissopulos S., Koehler P. E., Leoni S., Million B., Nyhus H.T., Renstrøm T.T., Rose S., Ruud I.E., Schiller A., Siem S., Tornyi T., Tveten G. M., Voinov A. V., and Wiedeking M.

Subjects
Physics, QC1-999
Abstract

An unexpected enhancement in the low-energy part of the γ-strength function for light and medium-mass nuclei has been discovered at the Oslo Cyclotron Laboratory. This enhancement could lead to an increase in the neutron-capture rates up to two orders of magnitude for very exotic, neutron-rich nuclei. However, it is still an open question whether this structure persists when approaching the neutron drip line.

Published
2014
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17. Targeted Modulation of Chicken Genes In Vitro Using CRISPRa and CRISPRi Toolkit.

Author

Chapman B, Han JH, Lee HJ, Ruud I, and Kim TH

Subjects
Animals, Gene Expression Regulation, Transcriptional Activation, Cell Line, Chickens genetics, CRISPR-Cas Systems
Abstract

Engineering of clustered regularly interspaced short palindromic repeats (CRISPR) and the CRISPR-associated protein 9 (Cas9) system has enabled versatile applications of CRISPR beyond targeted DNA cleavage. Combination of nuclease-deactivated Cas9 (dCas9) and transcriptional effector domains allows activation (CRISPRa) or repression (CRISPRi) of target loci. To demonstrate the effectiveness of the CRISPR-mediated transcriptional regulation in chickens, three CRISPRa (VP64, VPR, and p300) and three CRISPRi (dCas9, dCas9-KRAB, and dCas9-KRAB-MeCP2) systems were tested in chicken DF-1 cells. By introducing guide RNAs (gRNAs) targeting near the transcription start site (TSS) of each gene in CRISPRa and CRISPRi effector domain-expressing chicken DF-1 cell lines, significant gene upregulation was induced in dCas9-VPR and dCas9-VP64 cells, while significant downregulation was observed with dCas9 and dCas9-KRAB. We further investigated the effect of gRNA positions across TSS and discovered that the location of gRNA is an important factor for targeted gene regulation. RNA sequencing analysis of IRF7 CRISPRa and CRISPRi- DF-1 cells revealed the specificity of CRISPRa and CRISPRi-based targeted transcriptional regulation with minimal off-target effects. These findings suggest that the CRISPRa and CRISPRi toolkits are an effective and adaptable platform for studying the chicken genome by targeted transcriptional modulation.

Published
2023
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18. The forest as a classroom: preparing for mental health practice.

Author

Eklund ML, Ruud I, and Grov EK

Abstract

Background: Positive effects of physical activity, health promotion and disease prevention, in treatment of mental illnesses are well documented. Mental health practice for nursing students highlights the important connection between physical activities and mental health. This study aims to examine the outcome from nursing students' participation using The forest as a classroom. Students' collaboration by problem solving, theoretical discussions and performance of activities in the forest serves as a repertoire of non-medical treatment strategies in mental health., Methods: The forest as a classroom was evaluated by means of an ad-hoc questionnaire including both standardized and open-ended questions. Data was analyzed by means of descriptive statistics and content analysis., Results: The results indicated enhanced knowledge about physical activity and its impact on mental health. However, the nursing students' experience challenge preserving theoretical exercises outdoor because sensory stimulation took attention away from learning., Conclusions: For nursing students it is essential to build a repertoire of treatment activities to care for patients having mental health problems. This kind of approach is supported by the students' learning in the forest. The pilot study highlights the importance of multiple methods of learning in nursing education.

Published
2016
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