Incidence and geographical distribution of cereal cyst nematode (CCN, Heterodera spp.) in winter wheat fields in Algeria

Incidència i distribució geogràfica del nematode enquistat dels cereals (CCN, Heterodera spp.) en camps de blat d’hivern d’Algèria Els nematodes enquistats dels cereals (CCN, Heterodera spp.) són els nematodes paràsits vegetals més nocius per al blat, especialment a les zones de conreu de cereals, arreu del món. L’estiu de 2015 vam prendre mostres en 22 camps de blat i les vam analitzar mitjançant la tècnica de l’embut de Fenwick. L’estudi va revelar que el 54,55 % dels camps de blat estaven infestats pel nematode enquistat dels cereals. La infestació es va observar en diverses localitzacions del nord d’Algèria, però no a la zona desèrtica del sud. Les densitats de població de CCN al sòl de les zones infestades van variar entre 0,6 ± 0,54 i 8,6 ± 19,96 quists/500 g de sòl sec. A més, vam trobar una mitjana de 56,33 ± 15,18 i 364,70 ± 81,93 segons estadis juvenils i ous per quist, respectivament. La infestació era més severa als camps dedicats al cereal de Draa Semar i Djendel, amb 86,6 ± 19,96 quists/500 g de sòl i 57,4 ± 17,55 quists/500 g de sòl, respectivament. Les taxes més baixes d’infestació es van observar als altres camps: Ras Elouad, Sidi Mbarek i Sedraia, amb 0,6 ± 0,54 quists/500 g de sòl, 1,6 ± 1,67 quists/500 g de sòl i 2,4 ± 1,67 quists/500 g de sòl, respectivament. Heterodera spp. estava distribuït en tota la zona de conreu de cereal d’Algèria i podria causar una pèrdua de rendiment econòmic en aquestes regions. En mostrem la distribució en un mapa.Dades publicades a Mendeley (Doi:10.17632/rtsbcn6k9y.2) Incidencia y distribución geográfica del nematodo enquistado de los cereales (CCN, Heterodera spp.) en campos de trigo de invierno de Argelia Los nematodos enquistados de los cereales (CCN, Heterodera spp.) son los nematodos parásitos vegetales más dañinos para el trigo, especialmente en las zonas de cultivo de cereales, en todo el mundo. En el verano de 2015 tomamos muestras en 22 trigales y las analizamos utilizando la técnica del embudo de Fenwick. El estudio reveló que el 54,55% de los trigales estaban infestados por nematodo enquistado de los cereales. La infestación se observó en varias localizaciones del norte de Argelia, pero no en la zona desértica del sur. Las densidades de población de CCN en el suelo de las zonas infestadas variaron entre 0,6 ± 0,54 y 8,6 ± 19,96 quistes/500 g de suelo seco. Además, hallamos un promedio de 56,33 ± 15,18 y 364,70 ± 81,93 segundos estadios juveniles y huevos por quiste,  respectivamente. La infestación era más severa en los campos dedicados al cereal de Draa Semar y Djendel, con 86,6 ± 19,96 quistes/500 g de suelo y 57,4 ± 17,55 quistes/500 g de suelo, respectivamente. Las tasas más bajas de infestación se observaron en los otros campos: Ras Elouad, Sidi Mbarek y Sedraia, con 0,6 ± 0,54 quistes/500 g de suelo, 1,6 ± 1,67 quistes/500 g de suelo y 2,4 ± 1,67 quistes/500 g de suelo, respectivamente. Heterodera spp. estaba distribuido en toda la zona de cultivo de cereal de Argelia y podría causar una pérdida de rendimiento económico en esas regiones. Mostramos la distribución en un mapa. Datos publicados en Mendeley (Doi:10.17632/rtsbcn6k9y.2)Cereal cyst nematodes (CCN, Heterodera spp.) are the most damaging plant-parasitic nematode species on wheat, causing severe economic loss in global wheat production. In summer 2015, we analyzed samples collected from 22 wheat fields in Algeria using the Fenwick can technique. The study revealed that 54.55 % of wheat fields were infested with cereal cyst nematodes. The species was observed in several locations in the northern part of Algeria but not in the southern desert area. Population densities of CCNs in soil varied between the regions at an infestation rate of between 0.6 ± 0.54 and 86.6 ± 19.96 cysts per 500 g of dried soil. Furthermore, we found an average of 56.33±15.18 and 364.70 ± 81.93 second-stage juveniles and eggs/cyst. The infestation was most severe in cereal fields in Draa Semar and Djendel with 86.6 ± 19.96 cyst/500g of soil and 57.4±17.55 cysts/500g of soil, respectively. Infestation was lowest in fields in Ras Elouad, Sidi Mbarek and Sedraia with 0.6 ± 0.54 cysts/500g of soil; 1.6 ± 1.67 cysts/500g of soil and 2.4 ± 1.67 cysts/500g of soil, respectively. Heterodera spp. was distributed throughout the cereal growing province in Algeria and could cause economic loss in these regions. Data published in Mendeley (Doi:10.17632/rtsbcn6k9y.2

First application of the Trojan Horse Method with a Radioactive Ion Beam: study of the 18^{18}F(p,αp,{\alpha})15^{15}O}} reaction at astrophysical energies

Measurement of nuclear cross sections at astrophysical energies involving unstable species is one of the most challenging tasks in experimental nuclear physics. The use of indirect methods is often unavoidable in this scenario. In this paper the Trojan Horse Method is applied for the first time to a radioactive ion beam induced reaction studying the $^{18}$F($p,{\alpha}$)$^{15}$O process at low energies relevant to astrophysics via the three body reaction $^{2}$H($^{18}$F,${\alpha}^{15}$O)n. The knowledge of the $^{18}$F($p, {\alpha}$)$^{15}$O reaction rate is crucial to understand the nova explosion phenomena. The cross section of this reaction is characterized by the presence of several resonances in $^{19}$Ne and possibly interference effects among them. The results reported in Literature are not satisfactory and new investigations of the $^{18}$F($p,{\alpha}$)$^{15}$O reaction cross section will be useful. In the present work the spin-parity assignments of relevant levels have been discussed and the astrophysical S-factor has been extracted considering also interference effectsComment: 7 pages, 4 figure

Fast-neutron induced background in LaBr3:Ce detectors

The response of a scintillation detector with a cylindrical 1.5-inch LaBr3:Ce crystal to incident neutrons has been measured in the energy range En = 2-12 MeV. Neutrons were produced by proton irradiation of a Li target at Ep = 5-14.6 MeV with pulsed proton beams. Using the time-of-flight information between target and detector, energy spectra of the LaBr3:Ce detector resulting from fast neutron interactions have been obtained at 4 different neutron energies. Neutron-induced gamma rays emitted by the LaBr3:Ce crystal were also measured in a nearby Ge detector at the lowest proton beam energy. In addition, we obtained data for neutron irradiation of a large-volume high-purity Ge detector and of a NE-213 liquid scintillator detector, both serving as monitor detectors in the experiment. Monte-Carlo type simulations for neutron interactions in the liquid scintillator, the Ge and LaBr3:Ce crystals have been performed and compared with measured data. Good agreement being obtained with the data, we present the results of simulations to predict the response of LaBr3:Ce detectors for a range of crystal sizes to neutron irradiation in the energy range En = 0.5-10 MeVComment: 28 pages, 10 figures, 4 Table

Low Energy States of 3181Ga50^{81}_{31} Ga_{50} : Elements on the Doubly-Magic Nature of 78^{78}Ni

Excited levels were attributed to $^{81}_{31}$Ga$_{50}$ for the first time which were fed in the $\beta$-decay of its mother nucleus $^{81}$Zn produced in the fission of $^{nat}$U using the ISOL technique. We show that the structure of this nucleus is consistent with that of the less exotic proton-deficient N=50 isotones within the assumption of strong proton Z=28 and neutron N=50 effective shell effects.Comment: 4 pages, REVTeX 4, 5 figures (eps format

Indirect techniques for astrophysical reaction rates determinations

Direct measurements of nuclear reactions of astrophysical interest can be challenging. Alternative experimental techniques such as transfer reactions and inelastic scattering reactions offer the possibility to study these reactions by using stable beams. In this context, I will present recent results that were obtained in Orsay using indirect techniques. The examples will concern various astrophysical sites, from the Big-Bang nucleo synthesis to the production of radioisotopes in massive stars

Low energy measurement of the 7Be(p,gamma)8B cross section

We have measured the cross section of the 7Be(p,gamma)8B reaction for E_cm = 185.8 keV, 134.7 keV and 111.7 keV using a radioactive 7Be target (132 mCi). Single and coincidence spectra of beta^+ and alpha particles from 8B and 8Be^* decay, respectively, were measured using a large acceptance spectrometer. The zero energy S factor inferred from these data is 18.5 +/- 2.4 eV b and a weighted mean value of 18.8 +/- 1.7 eV b (theoretical uncertainty included) is deduced when combining this value with our previous results at higher energies.Comment: Accepted for publication in Phys. Rev. Let

Status of the Standard Solar Model Prediction of Solar Neutrino Fluxes

The Standard Solar Model (BP04) predicts a total 8B neutrino flux that is 17.2% larger than measured in the salt phase of the SNO detector (and if it were significant it will indicate oscillation to sterile neutrinos). Hence it is important to examine in details uncertainties (and values) of inputs to the SSM. Currently, the largest fractional uncertainty is due to the new evaluation of the surface composition of the sun. We examine the nuclear input on the formation of solar 8B [S17(0)] and demonstrate that it is still quite uncertain due to ill known slope of the measured astrophysical cross section factor and thus ill defined extrapolation to zero energy. This yields an additional reasonably estimated uncertainty due to extrapolation of +0.0 -3.0 eV-b (+0% -14%). Since a large discrepancy exists among measured as well as among predicted slopes, the value of S17(0) is dependent on the choice of data and theory used to extrapolate S17(0). This situation must be alleviated by new measurement(s). The "world average" is driven by the Seattle result due to the very small quoted uncertainty, which we however demonstrate it to be an over-estimated accuracy. We propose more realistic error bars for the Seattle results based on the published Seattle data.Comment: Fifth International Conferenceon Non-Accelerator New Physics, Dubna, June 20-25, 2005. Work Supported by USDOE Grant No. DE-FG02-94ER4087

A new experiment for the determination of the 18F(p,alpha) reaction rate at nova temperatures

The 18F(p,alpha) reaction was recognized as one of the most important for gamma ray astronomy in novae as it governs the early 511 keV emission. However, its rate remains largely uncertain at nova temperatures. A direct measurement of the cross section over the full range of nova energies is impossible because of its vanishing value at low energy and of the short 18F lifetime. Therefore, in order to better constrain this reaction rate, we have performed an indirect experiment taking advantage of the availability of a high purity and intense radioactive 18F beam at the Louvain La Neuve RIB facility. We present here the first results of the data analysis and discuss the consequences.Comment: Contribution to the Classical Novae Explosions conference, Sitges, Spain, 20-24 May 2002, 5 pages, 3 figure

Gamma ray production cross sections in proton induced reactions on natural Mg, Si and Fe targets over the proton energy range 30 up to 66 MeV

Gamma-ray excitation functions have been measured for 30, 42, 54 and 66 MeV proton beams accelerated onto C + O (Mylar), Mg, Si, and Fe targets of astrophysical interest at the separate-sector cyclotron of iThemba LABS in Somerset West (Cape Town, South Africa). A large solid angle, high energy resolution detection system of the Eurogam type was used to record Gamma-ray energy spectra. Derived preliminary results of Gamma-ray line production cross sections for the Mg, Si and Fe target nuclei are reported and discussed. The current cross section data for known, intense Gamma-ray lines from these nuclei consistently extend to higher proton energies previous experimental data measured up to Ep ~ 25 MeV at the Orsay and Washington tandem accelerators. Data for new Gamma-ray lines observed for the first time in this work are also reported.Comment: 11 pages, 6 figures. IOP Institute of Physics Conference Nuclear Physics in Astrophysics VII, 28th EPF Nuclear Physics Divisional Conference, May 18-22 2015, York, U

Search for new resonant states in 10C and 11C and their impact on the cosmological lithium problem

The observed primordial 7Li abundance in metal-poor halo stars is found to be lower than its Big-Bang nucleosynthesis (BBN) calculated value by a factor of approximately three. Some recent works suggested the possibility that this discrepancy originates from missing resonant reactions which would destroy the 7Be, parent of 7Li. The most promising candidate resonances which were found include a possibly missed 1- or 2- narrow state around 15 MeV in the compound nucleus 10C formed by 7Be+3He and a state close to 7.8 MeV in the compound nucleus 11C formed by 7Be+4He. In this work, we studied the high excitation energy region of 10C and the low excitation energy region in 11C via the reactions 10B(3He,t)10C and 11B(3He,t)11C, respectively, at the incident energy of 35 MeV. Our results for 10C do not support 7Be+3He as a possible solution for the 7Li problem. Concerning 11C results, the data show no new resonances in the excitation energy region of interest and this excludes 7Be+4He reaction channel as an explanation for the 7Li deficit.Comment: Accepted for publication in Phys. Rev. C (Rapid Communication