Structure around the island of inversion with single-neutron knockout reactions at GANIL

CERN-Proceedings-2010-001 available at http://www.fluka.org/Varenna2009/procmat.htmInternational audienceThe nuclear structure of the 31Mg nucleus has been studied with the singleneutron knockout reaction. We report on the preliminary results of an experiment performed with the EXOGAM array coupled, for the first time, to the SPEG spectrometer at GANIL.We present a provisional result for the inclusive single-neutron knockout cross section of σinc= 90(5) mb. Preliminary exclusive cross sections for the measured bound states, including the ground state, are also presented. Finally, preliminary longitudinal momentum distributions for the ground state and first excited state are also shown. These results are compared to Monte Carlo Shell-Model calculations in the sd-pf region

Re-examining the transition into the N=20 island of inversion: structure of 30Mg

Intermediate energy single-neutron removal from $^{31}$Mg has been employed to investigate the transition into the N=20 island of inversion. Levels up to 5~MeV excitation energy in $^{30}$Mg were populated and spin-parity assignments were inferred from the corresponding longitudinal momentum distributions and $\gamma$-ray decay scheme. Comparison with eikonal-model calculations also permitted spectroscopic factors to be deduced. Surprisingly, the 0$^{+}_{2}$ level in $^{30}$Mg was found to have a strength much weaker than expected in the conventional picture of a predominantly $2p - 2h$ intruder configuration having a large overlap with the deformed $^{31}$Mg ground state. In addition, negative parity levels were identified for the first time in $^{30}$Mg, one of which is located at low excitation energy. The results are discussed in the light of shell-model calculations employing two newly developed approaches with markedly different descriptions of the structure of $^{30}$Mg. It is concluded that the cross-shell effects in the region of the island of inversion at Z=12 are considerably more complex than previously thought and that $np - nh$ configurations play a major role in the structure of $^{30}$Mg.Comment: Physics Letters B, Volume 779, 10 April 2018, Pages 124-12

Determination of immune response of Newcastle disease virus vaccines in layer chickens

The study was conducted for the detection of persistence of Maternally derived antibody (MDA) as well as the comparative evaluation of antibody production of nine different NDV vaccines in layer chickens in the Department of Microbiology and Hygiene, Bangladesh Agricultural University, Mymensingh during the period from July to December 2008. A total of 55 layer chicks (ISA Brown breed) were divided into eleven groups each consisting of five birds of which odd number groups were vaccinated primarily with Nobilis® MA5+Clone 30, Avipro® ND-IB HB1, Cevac® BIL, Newcastle-Bronchitis Vaccine Fortdoge® and Avipro® ND LaSota vaccine respectively at day 5 of age and secondarily with Nobilis® ND Clone30, Avipro® ND LaSota, Cevac® New L, Newcastle Disease Vaccine Fortdoge® and Avipro® ND LaSota vaccine respectively at day 21 of age by single eye instillation and even number groups were vaccinated with the same vaccines respectively by double eye instillation following the same schedule. Again group 9 and group 10 were also vaccinated with RDV at 60 days of age through intramuscular route. Group 11 was kept as unvaccinated control. Sera samples were collected after 10 days of each vaccination and at day 5, 15, 20, 31 of age from unvaccinated control and subjected to HI test for the determination of antibody titres. It was observed that after primary vaccination the mean of HI titres of double eye vaccinated groups differed significantly (P<0.01). Overall analysis of mean of HI titres of double eye vaccinated groups revealed that there were significant increases (P<0.01) in HI titres in groups 8 (891.44±228.97) and 10 (861.66±140.21) compared to other groups. It was observed that secondary vaccination produced higher immune response compared to primary vaccination in case of all the vaccinated groups and double eye vaccination produced higher immune response compared to single eye vaccination in case of all the vaccinated groups. It was also observed that following vaccination with RDV in groups 9 and 10, HI titres increased significantly (P<0.01) which indicated that group 10 (1204.30±280.43 ) produced significantly higher antibody titres than group 9 (966.74±144). Maternal antibody was high (483.37±181.01) at day 5 of age and persisted to a minimal level (8.00±0.00) until the age of day 20 and almost disappears (≤4±0) at day 31 of age. From the present research it may be concluded that LaSota strain produced higher immune response than Clone 30 and B1 strain, Fortdose® and Avipro® vaccine produced higher immune response than all other vaccines and vaccination with lentogenic strains followed by mesogenic strain produced higher antibody titers used in this study

Direct radiative proton capture 23Al(p,α\alpha)24Si studied via one-proton nuclear breakup of 24Si

Expérience GANIL/SPEGInternational audienceWe present the results of an experimental work that studied the direct component of the radiative proton capture reaction 23Al(p,$\gamma$)24Si for its relevance in X-ray burst nucleosynthesis. The experiment was performed at GANIL using one-proton nuclear breakup reaction at intermediate energies to determine the Asymptotic Normalization Coefficient (ANC) of the system 24Si $\rightarrow$ 23Al + p. Using the ANC, we evaluated the corresponding astrophysical S factor and reaction rate

Astrophysically important reaction rates for novae and X‐ray bursts from proton breakup at intermediate energies

Expérience GANILInternational audienceWe discuss the use of one‐nucleon removal reactions of loosely bound nuclei at intermediate energies as an indirect method in nuclear astrophysics. The breakup reactions are proved to be good spectroscopic tools and can be used to study a large number of loosely bound proton‐ or neutron‐rich nuclei over a wide range of beam energies. As peripheral processes, they can be used to extract asymptotic normalization coefficients (ANCs) from which non‐resonant capture reaction rates of astrophysical interest can be calculated parameter free. In this talk, we present results of a proton‐breakup experiment carried out at GANIL (France) with a cocktail beam centered around 23Al at 50 MeV/nucleon. Momentum distributions of the breakup fragments, inclusive and in coincidence with gamma rays detected by EXOGAM Germanium clover array, were measured in the focal plan of SPEG energy‐loss spectrometer. We present in particular the investigations of reaction rates for 22Mg(p,γ)23Al and 23Al(p,γ)24Si important for novae and X‐ray bursts, respectively

Structure around the island of inversion with single-neutron knockout reactions at GANIL

CERN-Proceedings-2010-001 available at http://www.fluka.org/Varenna2009/procmat.htmInternational audienceThe nuclear structure of the 31Mg nucleus has been studied with the singleneutron knockout reaction. We report on the preliminary results of an experiment performed with the EXOGAM array coupled, for the first time, to the SPEG spectrometer at GANIL.We present a provisional result for the inclusive single-neutron knockout cross section of σinc= 90(5) mb. Preliminary exclusive cross sections for the measured bound states, including the ground state, are also presented. Finally, preliminary longitudinal momentum distributions for the ground state and first excited state are also shown. These results are compared to Monte Carlo Shell-Model calculations in the sd-pf region

How sharp is the transition into the N=20 island of inversion for the Mg isotopes?

The N=20 island of inversion is an excellent playground for testing shell model calculations. The Mg chain is a region of shell evolution still far from being well understood. In this paper we present preliminary results of a single-neutron knockout experiment from ³¹Mg performed at GANIL to study the structure of ³¹Mg and of the core ³⁰Mg. The level scheme and longitudinal momentum distributions were mesured and spectroscopic factors were deduced. Negative parity states arise at low energy and the spectroscopic factor for the isomeric 0²₊ in ³⁰Mg was determined to be smaller than foreseen in the standard picture. The preliminary experimental results are compared to state-of the art shell model calculations revealing opposed interpretations