66Ga: a standard for high-energy calibration of Ge detectors

Baglin, Coral M.; Browne, E.; Norman, E. B.; Molnár, Gábor; Belgya, T.; Révay, Zs.; Szelecsényi, F.

doi:10.1016/s0168-9002(01)01376-6

Cited by 34 publications

(22 citation statements)

References 21 publications

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“…66 Ga is easy to produce by proton bombardment of natural zinc and is therefore a useful isotope for detector efficiency and energy calibrations [1].…”

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confidence: 99%

Half-life ofGa66

et al. 2010

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We measured the half-life of 66 Ga by observing positrons from the β + branch to the ground state of 66 Zn with a superconducting Wu-type beta spectrometer. Our result is t 1/2 = 9.304(8) hours, which is the highest-precision measurement to date and disagrees with the Nuclear Data Sheets (NDS) value by over 6σ .The nucleus 66 Ga decays by electron capture and positron emission to 66 Zn with a half-life of more than nine hours, emitting β's up to 4.15 MeV and several γ 's with energies exceeding 2 MeV. 66 Ga is easy to produce by proton bombardment of natural zinc and is therefore a useful isotope for detector efficiency and energy calibrations [1].While in the process of carrying out a calibration experiment for a β spectrometer, we noticed that the half-life of 66 Ga is significantly shorter than the value quoted in the most recent Nuclear Data Sheets evaluation [2], and in light of this, we decided to carry out a dedicated experiment to measure the half-life.Previous measurements [3-9] of the 66 Ga half-life are summarized in Table I. The table also lists the values adopted in the recent evaluations by Woods [10] and by Browne [2]. The values adopted in the two evaluations are not in good agreement.Our experiment consisted of detecting positrons from the ground-state decay of 66 Ga in the Wisconsin Superconducting Beta Spectrometer (WSBS). The WSBS is an iron-free double focusing Wu-type beta spectrometer with a momentum acceptance of roughly 2% full width at half maximum (FWHM) and peak solid angle greater than 0.5 sr [11]. Positrons that pass through the spectrometer are detected with a 10 mm diameter, 5-mm thick Si(Li) detector. The detector has excellent energy resolution for stopped particles (about 10 keV FWHM), and the resulting capability to independently measure the energy of the momentum-selected β's allows for checks on systematic errors in the experiment.The 66 Ga was produced by proton irradiation of a 3 mg/cm 2 natural zinc target. The zinc had been vapor deposited onto a 13-µm thick aluminum foil, mounted on one of the spectrometer source holders. The reaction proceeded as 66 Zn(p,n) 66 Ga with bombardment at 7 MeV using 2 µA of beam for about 30 minutes at the Wisconsin Tandem Accelerator Lab. The target was allowed to sit for one hour to permit short-lived isotopes such as 64 Ga and 66 Cu to decay to negligible levels. It was then inserted into the counting position of the spectrometer.Data collection runs were taken at four different WSBS magnet current settings. Two of the settings were used to measure background rates, 0 A which is nonfocusing, and 20 A, corresponding to a beta momentum of 4.96 MeV/c, which is well above the beta decay endpoint as well as the internal conversion electron lines from states in 66 Zn. The other two currents, 11 and 14 A, with momenta centered at 2.73 and 3.47 MeV, respectively, were used for decay counting. The choice of relatively high momenta for decay counting helps to reduce the possibility of contributions from contaminants.Counting proceeded for 52 hours...

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“…66 Ga is easy to produce by proton bombardment of natural zinc and is therefore a useful isotope for detector efficiency and energy calibrations [1].…”

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confidence: 99%

Half-life ofGa66

et al. 2010

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“…This problem was first identified by McCallum and Coote [31] and has been discussed further by Baglin et al [32]. This problem was first identified by McCallum and Coote [31] and has been discussed further by Baglin et al [32].…”

Section: Discussionmentioning

confidence: 94%

The Evaluation of Gamma Ray Emission Probabilities in the Decay of 56Co

MacMahon¹,

Baglin²

2005

AIP Conference Proceedings

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56 Co is a radioactive source that is particularly suitable for the calibration of gamma-ray detector efficiencies, as it provides a number of gamma rays of usable intensity with energies up to 3.5 MeV. Data published in 31 papers between 1965 and 2002 for 45 gamma rays with energies between 263 keV and 3612 keV have been reviewed and evaluated. Methods for the evaluation of discrepant data are discussed. Problems with detector efficiency calibrations above 3 MeV have been identified and are addressed.

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“…The in-beam spectrum was collected with our standard Compton-suppressed HPGe detector (25% efficiency) [5], placed at 23.5 cm from the target to keep the count rate sufficiently low and suppress coincidence summing. The relative efficiency was determined using radioactive sources and capture γ -rays as described elsewhere [6]. Partial cross-sections for the strong 172, 223 and 263 keV capture γ -rays [7,8] as well as for the 539 and 591 keV γ -rays from 100 Tc decay [9] were determined from the same in-beam spectrum.…”

Section: Methodsmentioning

confidence: 99%

Partial and total thermal neutron capture cross sections for non-destructive assay and transmutation monitoring of ⁹⁹Tc

et al. 2002

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Thermal neutron capture / Gamma rays / Cold neutrons /Cross section / k 0 method / PGAA / NAA / Technetium 99 / Technetium 100 / Beta decay Summary. Accurate partial gamma-ray production cross sections were determined for the prompt and radioactive product decay gamma rays following cold neutron capture in 99 Tc. They can be used for non-destructive assay of technetium by prompt gamma activation analysis (PGAA) and neutron activation analysis (NAA), offering orders of magnitude higher analytical sensitivities than passive gamma-ray counting. A lower limit of 21.21 ± 0.17 b was also deduced for the thermal-neutron-capture cross section.

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66Ga: a standard for high-energy calibration of Ge detectors

Cited by 34 publications

References 21 publications

Half-life ofGa66

Half-life ofGa66

The Evaluation of Gamma Ray Emission Probabilities in the Decay of 56Co

Partial and total thermal neutron capture cross sections for non-destructive assay and transmutation monitoring of ⁹⁹Tc

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66Ga: a standard for high-energy calibration of Ge detectors

Cited by 34 publications

References 21 publications

Half-life ofGa66

Half-life ofGa66

The Evaluation of Gamma Ray Emission Probabilities in the Decay of 56Co

Partial and total thermal neutron capture cross sections for non-destructive assay and transmutation monitoring of 99Tc

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Partial and total thermal neutron capture cross sections for non-destructive assay and transmutation monitoring of ⁹⁹Tc