N. Arena

Energy and Width Measurement of the 9B First Excited State Observed by the 10B(3He, α)9B(p)8Be and 10B(3He, α)9B(α)5Li Reactions

An appropriate choice of the beam energies and detector geometries allowed us to observe the first excited 9B state through the p-8Be and α-5Li decay channels populated by the 10B(3He, α)9B(p)8Beg.s. and 10B(3He, α)9B(α)5Lig.s. reactions at E(3He) = 2.3 and 5 MeV, respectively. The excitation energy Ex and the state width Γ have been deduced.

Experimental evidence of the13D16Li state at about 5.7 MeV excitation energy

SummaryThe αd bidimensional spectra for the7Li(3He, ααd) reaction at

The 4.3 MeV6li state width deduced from the7Li(3He, αd)α reaction at E3He = 2.5 MeV

E_{{}^3He} = 2.5

5Lig.s. energy spectrum deduced by the6Li(3He, αp) α reaction

and 5 MeV, at various detection angles, have been measured. The peak corresponding to an ad relative energy of about 5.7 MeV, found in the spectra, has been analysed. By taking this peak to be mainly contributed by the13D16Li state at 5.7 MeV, the values of the excitation energy and of the width of this state are given.

Measurement of the 4. 8-MeV /sup 9/B state width by the reaction /sup 10/B(/sup 3/He,. cap alpha. )/sup 9/B(. cap alpha. ) /sup 5/Li at E( /sup 3/He) = 2. 3 and 5. 0 MeV

The αd bidimensional spectra for the 7 Li( 3 He, αd)α reaction at E ( 3 He)=11.5 have been measured. The width of the ( J π =1 + , T =0) level of the 6 Li nucleus at E x =5.65 MeV excitation energy have been deduced. The \(\varGamma\) value of (1.6±0.3) MeV found is in line with the values deduced by the same reaction at incident energies of E ( 3 He)=2.5 and 5.0 MeV. This shows that, in the range between 2.5 and 11.5 MeV, the apparent \(\varGamma\) width value does not seem to depend on the 3 He bombarding energy.

Measurement of the 4.8-MeV 9B state width by the reaction 10B(3He, alpha )9B( alpha ) 5Li at E( 3He

SummaryThe dα bidimensional spectra for the7Li(3He, αd)α reaction at E3He = = 2.5 MeV have been measured. The 4.3 MeV6Li state contribution has been isolated from the other products of the reaction. The value of (1.6±0.3) MeV found for its width is, within the experimental errors, in line with those deduced from the6Li(d, d’) and6Li(p, pα)d reactions, but it is a factor of about 3 larger than the ones measured in the7Li(3He, αd)α and6Li(e, e’) experiments.

Excitation energy and width of the first excited state in 5 Li from the 6 Li( 3 He, αp)α reaction

The reaction 7 Li( d , αα) n was studied by detecting αα coincidences with a forward-forward and a forward-backward geometry at 1.4, 2.1 and 2.5 MeV incident deuteron energies. The analysis of the αα bidimensional spectra allowed us to isolate the first excited 5 He state from other reaction products. The values of (3.8±0.3) MeV and of (3.1±0.5) MeV for the excitation energy and width of this state were found, respectively.

Complete and incomplete fusion in the reaction {sup 35}Cl+{sup 12}C at the energy range 70{endash}154 MeV

SummaryThe αα bidimensional spectra of the6Li(3He, αp)α reaction atE(3He)=2.5 MeV were analysed. The peak energyE* and the Γ width of the5Lig.s. nucleus were deduced. Each energy spectrum was fitted by an incoherent sum of the contributions coming from the g.s. and the first excited state of the5Li nucleus. A test was performed to verify whether experimental data could be fitted by a single-levelR-matrix calculation.RiassuntoSono stati analizzati gli spettri bidimensionali αα della reazione6Li(3He, αp) α ad energia incidente di 2.5 MeV e sono state misurate l’energia di piccoE* e l’ampiezza Γ dello stato fondamentale del5Li. Ogni spettro energetico è stato trattato con una somma incoerente dei contributi dovuti allo stato fondamentale ed al primo stato eccitato del5Li. Utilizzando la matriceR, è stato eseguito un fit dei dati sperimentali allo scopo di verificare se lo spettro energetico del5Li potesse essere riprodotto solo con l’ausilio di un singolo livello.РезюмеАнализируются двумерные спектры αα из реакции6Li(3He, αp) α приE (3He)=2.5 МэВ. Определяются положение максимальной энергииE* и ширины Γ для основного состояния5Li. Каждый энергетический спектр представляется в виде некогерентной сумму вкладов от основного состояния и первого возбужденного состояния ядер5Li. ИспользуяR-матрицу, предпринимается попытка объяснения экспериментальных данных, если предположить, что энергетический спектр может быть воспроизведен с помощью толяко одного уровня.