Refer to Guide E 844
Refer to Test Method E 261
Titanium has good physical strength, is easily fabricated, has excellent corrosion resistance, has a melting temperature of 1675°C, and can be obtained with satisfactory purity.
46Sc has a half-life of 83.79 days. The 46Sc decay emits a 0.8893 MeV gamma 99.984 % of the time and a second gamma with an energy of 1.1205 MeV 99.987 % of the time.
The isotopic content of natural titanium recommended for 46Ti is 8.25 %.
The radioactive products of the neutron reactions 47Ti(n,p)47Sc (τ1/2 = 3.3492 d) and 48Ti(n,p)48Sc (τ1/2 = 43.67 h), might interfere with the analysis of 46Sc.
Contaminant activities (for example, 65Zn and 182Ta) might interfere with the analysis of 46Sc. See Sections 7.1.2 and 7.1.3 for more details on the 182Ta and 65Zn interference.
46Ti and 46Sc have cross sections for thermal neutrons of 0.59 and 8 barns, respectively ; therefore, when an irradiation exceeds a thermal-neutron fluence greater than about 2 × 1021 cm–2, provisions should be made to either use a thermal-neutron shield to prevent burn-up of 46Sc or measure the thermal-neutron fluence rate and calculate the burn-up.
Fig. 1 shows a plot of cross section versus neutron energy for the fast-neutron reactions of titanium which produce 46Sc [that is, NatTi(n,X)46Sc]. Included in the plot is the 46Ti(n,p) reaction and the 47Ti(n,np) contribution to the 46Sc production, normalized (at 14.7 MeV) per 46Ti atom. This figure is for illustrative purposes only to indicate the range of response of the 46Ti(n,p) reaction. Refer to Guide E 1018
1.1 This test method covers procedures for measuring reaction rates by the activation reactions 46Ti(n,p) 46Sc + 47Ti(n, np)46Sc.
Note 18212;Since the cross section for the (n,np) reaction is relatively small for energies less than 12 MeV and is not easily distinguished from that of the (n,p) reaction, this test method will refer to the (n,p) reaction only.
1.2 The reaction is useful for measuring neutrons with energies above approximately 4.4 MeV and for irradiation times up to about 250 days (for longer irradiations, see Practice E 261
1.3 With suitable techniques, fission-neutron fluence rates above 109 cm–2·s–1 can be determined. However, in the presence of a high thermal-neutron fluence rate, 46Sc depletion should be investigated.
1.4 Detailed procedures for other fast-neutron detectors are referenced in Practice E 261
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its......
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