Cross-section measurements and production of ⁷²Se with medium to high energy protons using arsenic containing targets

Abstract

Experiments were performed to evaluate production of 72Se, parent radionuclide of the positron emitter 72As, at high energy at the Brookhaven Linac Isotope Producer (BLIP). Excitation functions for 75As(p, xn)72/75Se in the 52-105 MeV energy range were measured by irradiating thin gallium arsenide (GaAs) wafers. Maximum cross section value for the natAs(p, 4n)72Se reaction in the energy range was 103±9 mb at 52±1 MeV. Production size GaAs and arsenic metal (As°) targets were irradiated with 136 μA and 165 μA beam current possessing an initial Linac energy of 117 MeV. A total of 3.77±0.1 GBq (102±3 mCi) of 72Se was produced from a GaAs target at a calculated target entrance energy of 105.4 MeV, and 13.8±0.3 GBq (373±8 mCi) of 72Se from an As° target at a calculated incident energy of 49.5 MeV irradiated for 116.5 h and 68.9 h, respectively.

Continuing Nuclear Data Research for Production of Accelerator-Based Novel Radionuclides for Medical Use: A Mini-Review

“…Such accelerator facilities are now available at several places, for example Nantes (France), Legnaro (Italy), Moscow (Russia), Cape Town (South Africa), Brookhaven (United States), and Los Alamos (United States). A recent example is the measurement of the excitation function of the 75 As (p,4n) 72 Se reaction [31] for the production of 72 Se which is useful for preparing the β + -emitting generator system 72 Se/ 72 As.…”

Measurement and modeling of proton-induced reactions on arsenic from 35 to 200 MeV

“…The beam current during operation was recorded using toroidal beam transformers and shown to remain stable under these conditions for the duration of the irradiation. The mean beam energy extracted was 200 MeV with an approximately 0.2% uncertainty [7].…”

“…72 As offers the similar slow kinetic behaviour as the PET isotope 124 I (t 1/2 = 4.1760 (3) d, 22.7 (13)% β + [4]) but with a higher positron emission decay branch [5]. Furthermore, 72 As can form a promising pair with 77 As (t 1/2 = 38.83 (5) h, 100.0 (4)% β − , 683.2 (17) keV E β − ,max [6]) for combined imaging and radiotherapy [7][8][9]. The high sulfur affinity of arsenic, promoting its covalent binding to thiol groups, along with the toxicity of the 77 As decay spectrum, make 72 As/ 77 As an unique theranostic candidate [8,10].…”

“…Production of a generator results in 72 As free from other radioarsenic contaminants, on account of advantageous lifetime differences between 72 Se and neighboring Se nuclei, and availability restrictions at medical facilities across the globe. Measurements of a nat Br(p,x) 72 Se production route have been undertaken but the thick target yields, even approaching 200 MeV incident protons, are relatively low [3,7,12,13]. Bromine targets subjected to high power may also pose heating and/or reactivity problems [12,13].…”

Investigating High-Energy Proton-Induced Reactions on Spherical Nuclei: Implications for the Pre-Equilibrium Exciton Model

“…The beam current during operation was recorded using toroidal beam transformers and remained stable under these conditions for the duration of the irradiation. The mean beam energy extracted was 200 MeV at a 0.2% uncertainty [24].…”