Thick-target Gamma-ray Yields Research Articles

Differential cross-section measurement for 10B(p, αγ1)7Be, 10B(p, p’γ1)10B and 11B(p, p’γ1) 11B reactions

Differential cross-sections of the 10B(p, αγ1)7Be (Eγ = 429 keV), 10B(p, p’γ1)10B (Eγ = 718 keV) and 11B(p, p’γ1) 11B (Eγ = 2124 keV) reactions have been measured at proton laboratory energies of 912–2776 keV at 90°. The proton beam impinged on a thin natB2O3 film evaporated onto a self-supporting thin carbon layer. The incident energies were increased by 10 (20) keV steps in the resonance (off-resonance) regions. Our data are compared with the existing ones from literature. A benchmark procedure was performed by comparing the calculated thick-target yields from the current differential cross-sections with the existing measured thick target gamma-ray yields. The overall systematic uncertainty of the cross-sections was estimated to be about 10 %, mainly related to the target thickness determination.

Differential cross-section measurements of the 11B(d, pγ1,2)12B reactions for analytical applications

In the present work, the 11B(d, pγ)12B differential cross-sections for gamma- rays originating from the first two excited states of the 12B at 953 and 1674 keV were measured in the energy range Ed,lab = 671–1990 keV with steps of 30 or 40 keV at a detection angle of 90°. The target was a thin natB2O3 film evaporated onto a self-supporting Ag layer. The thick target gamma-ray yields were measured in the same experimental setup using a pressed pellet made of natB powder. The obtained results were compared with the existing data in literature. The validity of measured cross-sections was checked through a thick target benchmarking experiment.

12C(p,p′)12CReaction (Ep=19.5–30MeV) for Active Interrogation of Special Nuclear Material

Passive detection of special nuclear material (SNM) is challenging due to its inherently low rate of spontaneous emission of penetrating radiation, the relative ease of shielding, and the fluctuating and frequently overwhelming background. Active interrogation (AI), the use of external radiation to increase the emission rate of characteristic radiation from SNM, has long been considered to be a promising method to overcome those challenges. Current AI systems that incorporate radiography tend to use bremsstrahlung beams, which can deliver high radiation doses. Low-energy ion-driven nuclear reactions that produce multiple monoenergetic photons may be used as an alternative. The $^{12}$C(p,p')$^{12}$C is one such reaction that could produce large gamma-ray yields of highly penetrating 4.4- and 15.1-MeV gamma rays. This reaction does not directly produce neutrons below the $\sim$19.7-MeV threshold, and the 15.1-MeV gamma-ray line is well matched to the photofission cross-section of $^{235}$U and $^{238}$U. We report the measurements of thick-target gamma-ray yields at 4.4 and 15.1 MeV from the $^{12}$C(p,p')$^{12}$C at proton energies of 19.5, 25, and 30 MeV. Measurements were made with two 3'' EJ309 cylindrical liquid scintillation detectors and thermoluminescent dosimeters placed at 0 and 90 degrees. We estimate the highest yields of the 4.4- and 15.1-MeV gamma rays of 1.65$\times10^{10}$ sr$^{-1}\mu$ C$^{-1}$ and 4.47$\times10^8$ sr$^{-1}\mu$ C$^{-1}$ at a proton energy of 30 MeV, respectively. The yield of 4.4 and 15.1 MeV gamma rays in all experimental configurations is greater than a comparable deuteron-driven reaction that produces the same gamma-ray energies- $^{11}$B(d,n$\gamma$)$^{12}$C. However, a two orders of magnitude increase of the neutron radiation dose is observed when the proton energy increases from 19.5 to 30 MeV.

Measurement of deuteron induced gamma-ray emission cross sections on nitrogen for analytical applications

Deuteron induced gamma-ray emission cross-section values from the 14N(d,pγ4-1)15N (Eγ = 1885 keV), 14N(d,pγ6-1)15N (Eγ = 2297 keV), 14N(d,pγ5-0)15N (Eγ = 7299 keV) and 14N(d,pγ7-0)15N (Eγ = 8310 keV) nuclear reactions were measured in the 600–2000 keV range of the incident deuteron energies, in 30 keV steps at the laboratory angle of 90°, utilizing a thin C3H6N6 target evaporated onto a self-supporting Ag film. The thick target gamma-ray yields were measured in the same experimental setup using a thick TiN target. These measurements were conducted using the deuteron beam of the 3 MV Van de Graaff electrostatic accelerator of Nuclear Science and Technology Research Institute (NSTRI) in Tehran. The obtained results were compared with the previously reported data. The validity of the measured differential cross sections was verified through a thick target benchmarking experiment. The overall systematic uncertainty of the measured values was estimated and reported.

Thick target yields of proton induced gamma-ray emission from Al, Si and P

Thick target excitation yield curves of gamma-rays from the reactions 27Al(p,p′γ)27Al (Eγ=844 and 1014keV), 27Al(p,αγ)27Al (Eγ=1369keV), 28Si(p,p′γ)28Si (Eγ=1779keV), 29Si(p,p′γ)29Si (Eγ=1273keV) and 31P(p,p′γ)31P (Eγ=1266keV) were measured by bombarding pure-element targets with protons at energies below 3MeV. Gamma-rays were detected with a High Purity Ge detector placed at an angle of 90° with respect to the beam direction. The obtained thick target gamma-ray yields were compared with the previously published data. The overall systematic uncertainty of the thick target yield values was estimated to be better than ±9%.

Absolute alpha particle induced gamma-ray yields for Ti–Zn

Absolute thick-target gamma-ray yields for the elements Ti–Zn (excluding V) induced by alpha particles at energies of 5 and 10 MeV have been determined. Results for gamma-lines which could be considered for elemental analysis are tabulated and the relevant gamma-ray spectra are illustrated. In comparison to previous relative yield values available in the literature, a disagreement with the present results was found.

Absolute thick-target gamma-ray yields for the light elements induced by 12C, 14N and 16O ions

Thick-target gamma-ray yields for elements with Z=3–30 (excluding elements Z=10, 18, 21) at 12C ion energies of 22 and 28 MeV, for elements with Z=3–9 at 14N ion energy of 28 MeV and at 16O ion energies of 28 and 33 MeV have been determined. Tables of the most suitable gamma-ray lines for elemental analysis are given. The general applicability of 12C, 14N and 16O ions for prompt gamma-ray spectrometry simultaneously with backscattering analyses is discussed.

Thick-target γ-ray yields induced by 12 and 18 MeV 7Li ions

Thick-target gamma-ray yields for 49 elements with Z = 3–9, 11–17, 19, 20, 22–30, 32, 35, 39–42, 44, 46–51, 53, 62, 64, 70, 72–75, 78, 79 and 82 have been determined at incident 7Li ion energies of 12 and 18 MeV. A table of the most suitable gamma-ray lines for elemental analysis is given. The general applicability of 7Li ions for prompt analysis is discussed as well as the advantages and limitations of the method.

Coulomb excitation of 133Cs with protons

Protons of energy 3.2–4.2 MeV have been used to Coulomb excite the states in 133Cs. The thick-target gamma-ray yields and the angular distributions were measured using a 50 cm3 Ge(Li) detector. The measurements were used to extract the reduced transition probabilities, B (E2) and B(M1), and multipole mixing ratios (δ) for the various transitions. A spin assignment has been made to the 871.8 keV level on the basis of angular distribution data. The results obtained have been compared with those of other authors.

Absolute α-induced thick-target gamma-ray yields for the elemental analysis of light elements

A systematic study of the absolute thick-target yields of prompt γ-rays following 4He+ bombardment has been carried out at Eα=2.4 MeV for the elements Z=3−9, 11–14. The spectra of interest are depicted and a table of the most suitable γ-rays for elemental analysis is given. The detection limits are given under practical measuring arrangements. The advantage of the method is its good sensitivity for the detection of Li, Be, B and F on the ppm level even in samples containing high concentrations of other light elements such as Na, Mg and Al.

Heavy element ( Z > 30) thick-target gamma-ray yields induced by 1.7 and 2.4 MeV protons

Proton induced thick target γ-ray yields for elements with Z = 31–35, 37–42, 44–53, 55–60, 62–74, 78–82 at E p = 1.7 and 2.4 MeV have been tabulated and spectra given for the most interesting elements. In elements where γ-ray peaks were observed, the yields varied from 55 to 2 × 10 5 γ-rays/ μC·sr at E p = 2.4 MeV. In spite of the rather low γ-ray yields, the proton induced γ-ray emission (PIGE) method is applicable to heavy element determination under certain circumstances, as demonstrated. Of the suitable low yield elements, tin is recommended as a lining material for (p, γ) measurements.

Proton-induced thick-target gamma-ray yields for the elemental analysis of the Z=3–9, 11–21 elements

A systematic study of the relative thick-target yields of prompt γ-rays following proton bombardment has been carried out at Ep=1, 1.7 and 2.4 MeV for the elements Z=3–9, 11–21. The relevant spectra for each element are depicted and a table of the most suitable γ-rays for elemental analysis are given. Depending on the strength of the reaction cross section, the sensitivity limits of the detection vary from ppm to a few percent under practical measuring arrangements. Particular aspects of the measuring techniques are discussed.

Properties of the 4.77- and 5.16-MeV States ofB10

The energy levels in ${\mathrm{B}}^{10}$ at 4.77 and 5.16 MeV have been studied by means of the reactions ${\mathrm{B}}^{11}({\mathrm{He}}^{3},\ensuremath{\alpha}){\mathrm{B}}^{10}$ and ${\mathrm{Li}}^{6}(\ensuremath{\alpha},\ensuremath{\gamma}){\mathrm{B}}^{10}$. In measurements on the ${\mathrm{B}}^{11}({\mathrm{He}}^{3},\ensuremath{\alpha}){\mathrm{B}}^{10}$ reaction (${{E}_{\mathrm{He}}}^{3}=3.5$ MeV), alpha particles populating states of ${\mathrm{B}}^{10}$ were observed at 90\ifmmode^\circ\else\textdegree\fi{} in coincidence with (a) ${\mathrm{B}}^{10}$ recoil nuclei, (b) ${\mathrm{B}}^{10}$ recoils and gamma rays, and (c) decay alpha particles, by using two solid-state detectors and a NaI detector. Relative alpha-particle and gamma-ray branching intensities were determined for the decay of the 4.77- and 5.16-MeV states. The ratio of population intensities of the 5.16- and 5.11-MeV states was measured by using a Buechner-type magnetic spectrograph. In the ${\mathrm{Li}}^{6}(\ensuremath{\alpha},\ensuremath{\gamma}){\mathrm{B}}^{10}$ reaction thick-target gamma-ray yields were measured at resonances for forming the 4.77- and 5.16-MeV states. For the 4.77-MeV state the angular distribution of the predominant 4.05-MeV gamma ray was determined, the 4.77-MeV ground-state transition was detected, and the angular distribution of the 4.77-MeV gamma ray was measured. The intensity of the ground-state gamma-ray branch from the 4.77-MeV level was measured to be (0.5\ifmmode\pm\else\textpm\fi{}0.1)%, and the angular distribution of this transition in the ${\mathrm{Li}}^{6}(\ensuremath{\alpha},\ensuremath{\gamma}){\mathrm{B}}^{10}$ reaction favors an assignment of ${J}^{\ensuremath{\pi}}={3}^{+}$ to the 4.77-MeV state. Assignments of either ${J}^{\ensuremath{\pi}}={2}^{+} or {3}^{+}$ are allowed by the angular distribution of the 4.05-MeV transition from this state. $\frac{{\ensuremath{\Gamma}}_{\ensuremath{\gamma}}}{\ensuremath{\Gamma}}$ for the 4.77-MeV level was measured to be (2.3\ifmmode\pm\else\textpm\fi{}0.3)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}3}$. For the ${J}^{\ensuremath{\pi}}={3}^{+}$ assignment, partial widths for the 4.77-MeV level were measured to be ${\ensuremath{\Gamma}}_{\ensuremath{\gamma}}=0.033\ifmmode\pm\else\textpm\fi{}0.006$ eV and ${\ensuremath{\Gamma}}_{\ensuremath{\alpha}}=14\ifmmode\pm\else\textpm\fi{}3$ eV. The partial widths of the 5.16-MeV level were measured as ${\ensuremath{\Gamma}}_{\ensuremath{\gamma}}=2.9\ifmmode\pm\else\textpm\fi{}1.1$ eV and ${\ensuremath{\Gamma}}_{\ensuremath{\alpha}}=0.44\ifmmode\pm\else\textpm\fi{}0.09$ eV for an alpha-particle branch of (13\ifmmode\pm\else\textpm\fi{}4)%. The properties of these and neighboring states are discussed in terms of the independent-particle model. Good agreement is found on some striking features but several points remain to be clarified.

Gamma-ray branching of energy levels in 24Mg from the 23Na (p,γ) 24Mg reaction

The gamma-ray spectra at six 23Na(p,γ) 24Mg resonances in the E p = 300−750 keV region have been investigated with scintillation spectrometers. From single spectra, coincidence spectra and sum-coincidence spectra the gamma-ray branchings of the resonance levels and of eighteen lower 24Mg levels were obtained. At most resonances a 1.63 MeV gamma ray was observed, from which the relative intensity of the 23Na(p, α 1) 20Ne decay could be found. Thick target gamma-ray yields have been measured from which the resonance strengths were obtained.