Triton Beam Research Articles

K43from theK41(t,p) reaction

The reaction $^{41}\mathrm{K}$(t,p)$^{43}\mathrm{K}$ has been investigated with a 15-MeV triton beam. Twenty levels of $^{43}\mathrm{K}$ (many of them unreported previously) have been identified up to about 3.4 MeV excitation energy. Angular distributions were measured for all levels. Comparison with distorted-wave Born-approximation calculations allows extraction of $L$ values for most of them. Three multiplets arising from the couplings of ${(1{f}_{\frac{7}{2}})}_{J=2}^{2}$ and ${(1{f}_{\frac{7}{2}})}_{J=4}^{2}$ transferred neutrons with the $1{d}_{\frac{3}{2}}$ proton hole have been identified in $^{43}\mathrm{K}$. Their energy centroids are closely related to the ${(1{f}_{\frac{7}{2}})}^{4}$ spectrum of $^{44}\mathrm{Ca}$. The general sum rules for two-nucleon transfer reactions and a more specialized sum rule give a good account of the data and suggest spin and parity assignments for many of the observed states. The positive parity states in $^{43}\mathrm{K}$ are compared with ${f}_{\frac{7}{2}}^{4}{({d}_{\frac{3}{2}}{s}_{\frac{1}{2}})}^{\ensuremath{-}1}$ and ${f}_{\frac{7}{2}}^{3}{p}_{\frac{3}{2}}{d}_{\frac{3}{2}}^{\ensuremath{-}1}$ shell-model calculations.

Au197(t,p)Au199reaction

The level structure of /sup 199/Au was investigated via the /sup 197/Au(t,p) reaction induced with a 17 MeV triton beam. Essentially all of the L = 0 transfer strength is observed in the ground state transition. The distribution of L = 4 transfer strength follows the systematic behavior observed previously in the Pt(t,p) reactions.

As79via proton pickup

The reaction $^{80}\mathrm{Se}(\mathrm{t}, \ensuremath{\alpha})^{79}\mathrm{As}$ has been investigated with an 18-MeV triton beam. Twenty-six levels of $^{79}\mathrm{As}$ (many of them previously unreported) have been identified up to about 3.5 MeV excitation energy. Angular distributions were measured and compared with distorted-wave Born-approximation calculations, in order to extract $L$ values and spectroscopic factors. Most of the expected strength for pickup from the $2p$ and $1{f}_{\frac{5}{2}}$ orbitals is observed. Behavior of the low-lying negative-parity states for various As isotopes is presented and compared with the predictions of a rotational model with prolate deformation and Coriolis coupling. The observed first and second $\frac{9}{{2}^{+}}$ states in odd-$A$ isotopes give further evidence for the shape transition suggested recently for this mass region.NUCLEAR REACTIONS $^{80}\mathrm{Se}(\mathrm{t}, \ensuremath{\alpha})^{79}\mathrm{As}$, $E=18$ MeV; measured $\ensuremath{\sigma}({E}_{\ensuremath{\alpha}}, \ensuremath{\vartheta})$. $^{79}\mathrm{As}$ deduced levels, $L$, $\ensuremath{\pi}$, ($J$), spectroscopic factors. DWBA analysis, enriched target.

Single proton structure ofIr193,195,197and perturbed spin(6) symmetry

The $^{194,196,198}\mathrm{Pt}(\stackrel{\ensuremath{\rightarrow}}{t}, \ensuremath{\alpha})^{193,195,197}\mathrm{Ir}$ reactions have been studied with a 17 MeV polarized triton beam. Based on the measured angular distributions of cross sections and analyzing powers, several new ${I}^{\ensuremath{\pi}}$ assignments were made in $^{195}\mathrm{Ir}$ and new levels were identified in $^{197}\mathrm{Ir}$. The change in the distribution of ${d}_{\frac{3}{2}}$ spectroscopic strength as a function of neutron number is observed to be quite dramatic. Two large fragments are observed in $^{193}\mathrm{Ir}$, all of the ${d}_{\frac{3}{2}}$ strength is concentrated in the ground state of $^{197}\mathrm{Ir}$, and $^{195}\mathrm{Ir}$ shows a situation intermediate between these two. The empirical ${d}_{\frac{3}{2}}$ strength in $^{193}\mathrm{Ir}$ is well reproduced by the predictions of the $\mathrm{U}(\frac{6}{4})$ supersymmetry proposed for the Os-Ir-Pt nuclei. The change in the ${d}_{\frac{3}{2}}$ strength as a function of neutron number is well reproduced by a perturbation of this symmetry.NUCLEAR REACTIONS $^{194,196,198}\mathrm{Pt}(\stackrel{\ensuremath{\rightarrow}}{t}, \ensuremath{\alpha})$, ${E}_{t}=17$ MeV, enriched targets; measured $\ensuremath{\sigma}({E}_{\ensuremath{\alpha}}, \ensuremath{\theta})$, ${A}_{y}({E}_{\ensuremath{\alpha}}, \ensuremath{\theta})$. $^{193,195,197}\mathrm{Ir}$ deduced levels, $I$, $\ensuremath{\pi}$, spectroscopic strengths.NUCLEAR STRUCTURE Interacting boson fermion model, $\mathrm{U}(\frac{6}{4})$ supersymmetry, spin(6) symmetry.

The interactions of polarised tritons with 32S

Cross sections and analysing powers have been measured for the elastic and inelastic scattering of tritons from 32S, along with the 32 S( t, α) 31 P reaction data, using the 17 MeV polarised triton beam available at the Los Alamos National Laboratory. An optical model analysis of the elastic scattering data has yielded a triton spin-orbit potential with an unconventional geometry. The inelastic analysing powers have shown a requirement for including the deformation of the spin-orbit potential in the coupling potential form factor. The ( t, α ) reaction data have been analysed using the zero-range DWBA. Certain features of this reaction data which could not be described by the DWBA are well predicted when the analysis is extended to include explicitly the inelastic couplings and two-step processes through a CCBA calculation.

Fragmentation ofL=0transfer strength in thePt195(t, p)Pt197reaction

The /sup 195/Pt(t,p)/sup 197/Pt reaction has been measured with a 17 MeV triton beam. Excitation energies and angular distributions of states below 2.2 MeV have been obtained. Three sizable L = 0 transitions were observed to states below 1 MeV, in contrast to earlier Pt(t,p) and (p,t) reaction measurements where essentially all of the L = 0 strength was in the ground-state transition.

Investigation of the reactions3H+p to3He+n and3H+p to3H+p at a triton momentum of 2.5 GeV/c

The differential cross sections d sigma /dt of the reactions 3H+p to 3He+n and 3H+p to 3H+p at a triton momentum of 2.5 GeV/c (equivalent to a proton kinetic energy Tp=318 MeV) have been measured. The ITEP 80 cm hydrogen bubble chamber was exposed to a 2.5 GeV/c separated triton beam. 2350 events of the reaction 3H(p,n)3He and 2574 events of the reaction 3H(p,p)3H were selected and analysed. Calculations performed in the framework of the multiple scattering theory taking the spin-isospin structure of the NN amplitude into account fit the data very well and show the high sensitivity of the charge-exchange cross section to the double spin-flip NN amplitudes.

Mo92,94,97,98(t,p) reactions atEt=17MeV

A systematic study of the molybdenum isotopes has been carried out by using the ($t$,$p$) reaction with a 17-MeV incident triton beam. Energy levels up to excitation energies of 5.1, 4.7, 2.1, and 3.8 MeV in the isotopes $A=94, 96, 99, \mathrm{and} 100$, respectively, were studied, and numerous spin assignments were made. Of particular interest is the trend of ground state and excited ${0}^{+}$ state transition strengths, which suggest a rapidly changing structure of the molybdenum ground states as a function of neutron number. The interacting boson approximation model is able to reproduce these trends only with the introduction of configuration mixing.NUCLEAR REACTIONS $^{92,94,97,98}\mathrm{Mo}$($t$,$p$) measured $\ensuremath{\sigma}(\ensuremath{\theta})$ DWBA analysis.

Application of Nuclear Microlocalization Techniques to Biomedical Problems

Ion beams at the Brookhaven 3.5 MV Research Van de Graaff accelerator have been used for elemental analysis and distribution in biomedical samples. This paper will present results from several collaborations. Both collimated and uncollimated charged particle beams are used for elemental analysis by measurement of characteristic x-rays (PIXE). A collimated proton beam, using a pinhole collimator (~20 μm) has been used as a particle microprobe in the laboratory ambient. Thick, essentially unprepared, samples can be measured with general elemental sensitivities of ≲ 10 ppm. The spatial resolution and elemental sensitivity have proven adequate for many samples of tissue sections and cell clusters. Specimen damage by charged particle beams is discussed and results of cell irradiations by triton beams are presented. Deuterium localization has been carried out in cell uptake studies using the 2H(3H,n)4He reaction initiated by the triton beam at the accelerator. Alpha particles from the reaction register the deuterium distribution in a plastic track detector. This technique suggests that 3H may be replaced by the stable isotope H in tracer studies. Studies have included the detection of nonexchangeable 2H in oocytes and the uptake of deuterated thymidine in blood cells.

Acceleration of tritons with a compact cyclotron

With the compact cyclotron at the Faculty of the Technical University of Munich, tritons have been accelerated to an energy of 7 MeV. A safe and reliable operation of the gas supply for the ion source was obtained by a new tritium storage system. A quantity of 1500 Ci tritium is stored by two special Zr-Al getter pumps in a non-gaseous phase. The tritium can be released in well-defined amounts by heating the getter material. During triton acceleration the pressure in the cyclotron vacuum chamber is maintained only by a large titanium sputter-ion pump, thus forming a closed vacuum system without any exhaust of tritium contaminated gas. Any tritium contaminations in the air can be detected by an extremely sensitive tritium monitoring system. The triton beam with a maximum intensity of 30 μA has been used so far to produce neutron-rich radioisotopes such as 28Mg, 43K or 72Zn, which are successfully applied in tracer techniques in the studies of biological systems.

Charge-exchange [formula omitted] and elastic [formula omitted] differential cross sections at medium energy

The Saturne I quasi-monokinetic triton beam has been used to measure the p 3H → n 3He differential cross section at 415 and 600 MeV per nucleon and the p 3H → p 3H differential cross section at 415 MeV per nucleon. We covered the four-momentum transfer squared t domain from 0 down to −0.7 GeV/ c) 2. A spin-independent Glauber-model interpretation of the data is discussed.

Medium energy triton beam obtained by alpha particle fragmentation

A quasi-monokinetic triton beam of 10 7 particles per cycle and 3% momentum spread has been obtained by α-particle fragmentation. A possible extension of the method to exotic ions beams is briefly discussed, using recent high energy data about nuclear fragmentation of heavy ions.

Total Angular Momentum Determinations from the (tpol,d) Reaction onNi58,64

The (${t}_{\mathrm{pol}}$, $d$) reaction at 16 MeV has been used to determine the total angular momentum of levels in $^{59}\mathrm{Ni}$ and $^{65}\mathrm{Ni}$. This represents the first reported results of this reaction using a polarized triton beam. The data indicate distinct differences and advantages over (${d}_{\mathrm{pol}}$,$p$) data at similar bombarding energies. The (${t}_{\mathrm{pol}}$,$d$) reaction is used on $^{58}\mathrm{Ni}$ to compare data with distorted-wave Bron-approximation predictions for known spin states and on $^{64}\mathrm{Ni}$ to resolve an important controversy over spin values in $^{65}\mathrm{Ni}$.

Mass and excited states ofBe12

The $^{10}\mathrm{Be}(t, p)^{12}\mathrm{Be}$ reaction has been studied with a 94% enriched $^{10}\mathrm{Be}$O target, a 17-MeV triton beam, and a multiangle magnetic spectrograph. Proton groups from the ($t, p$) reaction on $^{12}\mathrm{C}$ and $^{16}\mathrm{O}$ in the target served for energy calibration. An average of data at four angles gives a ${Q}_{0}$ value of -4809 \ifmmode\pm\else\textpm\fi{} 15 keV, from which the mass excess of $^{12}\mathrm{Be}$ is calculated to be 25,077.5 \ifmmode\pm\else\textpm\fi{} 15 keV. Excited states of $^{12}\mathrm{Be}$ are found at 2089 \ifmmode\pm\else\textpm\fi{} 20, (2712 \ifmmode\pm\else\textpm\fi{} 20, tentative), 4559 \ifmmode\pm\else\textpm\fi{} 25, and 5703 \ifmmode\pm\else\textpm\fi{} 25 keV. The mass excess of $^{12}\mathrm{Be}$, plus earlier data for $A=12$, $T=2$, gives a value of $d=+2.8\ifmmode\pm\else\textpm\fi{}8.6$ keV for the coefficient of the cubic term in the isobaric multiplet mass equation.NUCLEAR STRUCTURE $^{12}\mathrm{Be}$: measured $Q$ values for proton groups in $^{10}\mathrm{Be}(t, p)^{12}\mathrm{Be}$ reaction; derived $^{12}\mathrm{Be}$ mass excess, ${E}_{\mathrm{exc}}$ of $^{12}\mathrm{Be}$ excited states, IMME coefficients.

Ge74(t, p)Ge76reaction

The reaction $^{74}\mathrm{Ge}(t, p)^{76}\mathrm{Ge}$ has been investigated with a 15 MeV triton beam. Twenty-six energy levels of $^{76}\mathrm{Ge}$ were identified up to about 4 MeV excitation, five of which were unreported previously. Angular distributions were measured and compared with distorted-wave Born-approximation calculations. The first and second excited 0+ states in $^{76}\mathrm{Ge}$ have been located at 1.911 and 2.901 MeV. Thirteen additional new spin and parity assignments have been made. The systematic structure of the low-lying 0+ states observed in the $\mathrm{Ge}(t, p)$ reactions on several isotopes support the idea of a shape transition previously proposed for these nuclei but for $N\ensuremath{\ge}46$ there is a rapid change toward a spherical shape.NUCLEAR REACTIONS $^{74}\mathrm{Ge}(t, p)$, ${E}_{t}=15.0$ MeV; measured $\ensuremath{\sigma}({E}_{p}, \ensuremath{\theta})^{76}\mathrm{Ge}$ deduced levels, $L$, $\ensuremath{\pi}$, $J$. DWBA analysis.

Structure of 74Ge from the 72Ge(t, p) reaction

Abstract The reaction 72Ge(t, p)74Ge has been investigated with a 15 MeV triton beam. Fifty energy levels of 74Ge were identified up to about 4.9 MeV excitation, eighteen of which were previously unreported. Angular distributions were measured and compared with DWBA calculations. Two low-lying states at 1.913 and 2.164 MeV have been assigned as Jπ = 0+, corresponding to the 03+ and 04+ states in 74Ge. The 42+ state has been located at 2.674 MeV, and the 24+ at 2.836 MeV. Many additional spin and parity assignments have been made. The 74Ge nucleus shows a considerably different structure of 0+ states compared with the neighboring 76Ge and 78Ge nuclei, perhaps further evidence for the shape transition suggested recently for the Ge isotopes.

Structure of 14C from 12C(t, p)

The reaction 12C(t, p) 14C has been investigated with an 18 MeV triton beam. Twenty energy levels of 14C were identified up to 13 MeV excitation. Angular distributions were measured and compared with DWBA calculations. A previously unreported 0 + level at 9.75 MeV was observed; it undoubtedly corresponds to the second predominantly sd shell 0 + state in 14C. Additional spin and parity assignments have been made in the present work: 9.81 MeV, (1 −); 10.43 MeV, 2 +; 10.50 MeV, (3 −); 10.74 MeV, 4 +; 11.40 MeV, 1 −; 11.67 MeV, (1 −); 11.73 MeV, (5 −); 12.58 MeV, (2 +, 3 −); 12.87 MeV. 2 +, 3 −; and 12.96 MeV, (1 −); none of which had a definite spin and parity assignment previously. Our results confirm the previous information on the level structure of 14C below 8.5 MeV. The cross section for the unnatural parity state at 7.34 MeV, J π = 2 −, is well reproduced by a two-step reaction calculation. The results are compared with the predictions of a weak coupling model.

Acceleration of tritium in an FN tandem accelerator

A cesium beam sputter ion source has been used to produce a negative triton beam of between 0.5 to 2.0 μA for injection into an FN tandem accelerator. The source successfully operated for a period of 600 h of experimentation, at a mean analyzed current level of about 1 μA on about 70 atm cm 3 of tritium enabling a large number of diverse experiments to be performed. Radioactive contamination of the accelerator and peripheral equipment proved minimal.

Os188,190,192(t,p)reaction at 15 MeV

A study of the heavier osmium isotopes $^{190}\mathrm{Os}$, $^{192}\mathrm{Os}$, and $^{194}\mathrm{Os}$ has been made with the ($t,p$) reaction using a 15 MeV triton beam. The osmium nuclei may be considered as transitional nuclei going from a deformed to a spherical shape with increasing neutron number and the ($t,p$) reaction is used to probe this change. The study principally investigates the position and strength of the ${0}^{+}$ states, a number of new such states being observed. The nucleus $^{194}\mathrm{Os}$ is also reported in some detail for the first time with 15 excited levels observed and 7 spin assignments made.[NUCLEAR REACTIONS $^{188,190,192}\mathrm{Os}(t,p)$, ${E}_{t}=15$ MeV. Measured $\ensuremath{\sigma}(\ensuremath{\theta})$; enriched targets; DWBA calculations deduced $J$, $\ensuremath{\pi}$.]

Damage to human blood cells caused by 200 keV triton bombardment

Fixed specimens of human blood cells have been bombarded by 200 keV triton beams with fluences up to 7 × 10 16 tritons/cm 2. The target chamber was filled with 0.5 atm of helium for heat transfer from the target. High magnification phase contrast photo-micrographs and low resolution scanning electron micrographs of the cells are used to show morphological details of radiation damage. Differences in images of the same radiation-damaged cells made with these two microscopy techniques are described. A fluence of 4 × 10 16 tritons/cm 2 was found to strip cytoplasm from white blood cells leaving their nuclei naked but intact. The same fluence caused relatively minor damage to red blood cells. Limits imposed by radiation damage on biomedical information that may be obtainable using triton bombardment to localize deuterated tracer metabolites in individual cells are discussed. A brief comparison with radiation damage observations in electron microscopy is also given.