The isotopic production and chemical purification of neptunium as a possible source for analytic reference material is reported. The aim was to maximize <InlineEquation ID="IEq3"> <EquationSource Format="TEX">$^{236}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>236</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>Np (<InlineEquation ID="IEq4"> <EquationSource Format="TEX">$T_{1/2}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>T</mi> <mrow> <mn>1</mn> <mo stretchy="false">/</mo> <mn>2</mn> </mrow> </msub> </math></EquationSource> </InlineEquation> = 155 ky) yield from a proton irradiation of a depleted uranium target and evaluate the relative production of the other long-lived isotopes <InlineEquation ID="IEq5"> <EquationSource Format="TEX">$^{237}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>237</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>Np (<InlineEquation ID="IEq6"> <EquationSource Format="TEX">$T_{1/2}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>T</mi> <mrow> <mn>1</mn> <mo stretchy="false">/</mo> <mn>2</mn> </mrow> </msub> </math></EquationSource> </InlineEquation> = 2.14 My) and <InlineEquation ID="IEq7"> <EquationSource Format="TEX">$^{235}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>235</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>Np (<InlineEquation ID="IEq8"> <EquationSource Format="TEX">$T_{1/2}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>T</mi> <mrow> <mn>1</mn> <mo stretchy="false">/</mo> <mn>2</mn> </mrow> </msub> </math></EquationSource> </InlineEquation> = 396 d). An efficient chemical purification procedure was developed to isolate the transmutated neptunium from the uranium target matrix and high-activity irradiation and decay products. Based on gamma and mass spectrometric analyses, the final neptunium product contained a <InlineEquation ID="IEq9"> <EquationSource Format="TEX">$^{236}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>236</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>Np mass of 6.15 <InlineEquation ID="IEq10"> <EquationSource Format="TEX">$\mu$</EquationSource> <EquationSource Format="MATHML"><math> <mi>μ</mi> </math></EquationSource> </InlineEquation>g indicating a production yield from the <InlineEquation ID="IEq11"> <EquationSource Format="TEX">$^{238}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>238</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>U(p, 3n) reaction of 125 ng/mA<InlineEquation ID="IEq12"> <EquationSource Format="TEX">$\cdot$</EquationSource> <EquationSource Format="MATHML"><math> <mo>·</mo> </math></EquationSource> </InlineEquation>h/g<InlineEquation ID="IEq13"> <EquationSource Format="TEX">$\cdot$</EquationSource> <EquationSource Format="MATHML"><math> <mo>·</mo> </math></EquationSource> </InlineEquation>cm<InlineEquation ID="IEq14"> <EquationSource Format="TEX">$^{-2}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mrow> <mo>-</mo> <mn>2</mn> </mrow> </mmultiscripts> </math></EquationSource> </InlineEquation> DU. The <InlineEquation ID="IEq15"> <EquationSource Format="TEX">$^{237}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>237</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>Np:<InlineEquation ID="IEq16"> <EquationSource Format="TEX">$^{236}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>236</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>Np and <InlineEquation ID="IEq17"> <EquationSource Format="TEX">$^{235}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>235</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>Np:<InlineEquation ID="IEq18"> <EquationSource Format="TEX">$^{236}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>236</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>Np production ratios, the former reported for the first time, were 11.5 and 1.91, respectively. Comparisons to expected production amounts based on literature cross sections showed good agreement between the isotopic ratios, however total masses indicated an underproduction in the present experiment by 50%. Higher <InlineEquation ID="IEq19"> <EquationSource Format="TEX">$^{236}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>236</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>Np isotopic purity may be achieved in future efforts if transmutated <InlineEquation ID="IEq20"> <EquationSource Format="TEX">$^{237}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mrow /> <mn>237</mn> </mmultiscripts> </math></EquationSource> </InlineEquation>U (<InlineEquation ID="IEq21"> <EquationSource Format="TEX">$T_{1/2}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>T</mi> <mrow> <mn>1</mn> <mo stretchy="false">/</mo> <mn>2</mn> </mrow> </msub> </math></EquationSource> </InlineEquation> = 6.75 d) could be separated from the neptunium product shortly following the irradiation.

Yield optimization of $^{236}$Np and quantification of long-lived Np isotopes produced in proton-irradiated DU

期刊论文
发表日期：

2026年7月24日

查看全文

Brian M. Bucher,
Peter R. Zalupski,
Jared J. Horkley,
Michael E. Fassbender,
Travis S. Grimes,
Ellen M. O’Brien,
Christiaan E. Vermeulen,
E. Paige Abel,
Kevin P. Carney,
Magen E. Coleman,
Tony D. Jones,
Kelly M. McCary,
Warren J. Oldham,
Cortney M. Pincock,
Michael A. Reichenberger,
John D. Stanek,
Andrew J. Zillmer

摘要

The isotopic production and chemical purification of neptunium as a possible source for analytic reference material is reported. The aim was to maximize $^{236}$ $^{236}$ Np ( $T_{1/2}$ $T_{1 / 2}$ = 155 ky) yield from a proton irradiation of a depleted uranium target and evaluate the relative production of the other long-lived isotopes $^{237}$ $^{237}$ Np ( $T_{1/2}$ $T_{1 / 2}$ = 2.14 My) and $^{235}$ $^{235}$ Np ( $T_{1/2}$ $T_{1 / 2}$ = 396 d). An efficient chemical purification procedure was developed to isolate the transmutated neptunium from the uranium target matrix and high-activity irradiation and decay products. Based on gamma and mass spectrometric analyses, the final neptunium product contained a $^{236}$ $^{236}$ Np mass of 6.15 $\mu$ $μ$ g indicating a production yield from the $^{238}$ $^{238}$ U(p, 3n) reaction of 125 ng/mA $\cdot$ $\cdot$ h/g $\cdot$ $\cdot$ cm $^{-2}$ $^{- 2}$ DU. The $^{237}$ $^{237}$ Np: $^{236}$ $^{236}$ Np and $^{235}$ $^{235}$ Np: $^{236}$ $^{236}$ Np production ratios, the former reported for the first time, were 11.5 and 1.91, respectively. Comparisons to expected production amounts based on literature cross sections showed good agreement between the isotopic ratios, however total masses indicated an underproduction in the present experiment by 50%. Higher $^{236}$ $^{236}$ Np isotopic purity may be achieved in future efforts if transmutated $^{237}$ $^{237}$ U ( $T_{1/2}$ $T_{1 / 2}$ = 6.75 d) could be separated from the neptunium product shortly following the irradiation.

Yield optimization of \(^{236}\)Np and quantification of long-lived Np isotopes produced in proton-irradiated DU

摘要