Development of natural, Cr-rich targets for Manganese-52 production | Aici

Target project

General equipment

Natural Cr metal powder of 5N purity, Ta plate of 3N8 purity, Al plate of 5N purity, Cu plate of 5N5 purity, Au plate of 5N purity and Pt rod of 3N5 purity were obtained from ESPI Metals, Ashland, OR. enriched 52Cr metal powder with 98.8% purity was obtained from Isoflex, San Francisco, CA. Viton O-rings were obtained from McMaster-Carr, Elmhurst, IL. A 10 mm diameter ID dry pressing set was obtained from Across International (Livingston, NJ). Chromium chloride hexahydrate of purity ≥ 98% and 1 mL SPE tubes with frits were obtained from Millipore Sigma, Burlington, MA. AG1-X8 resin analytical grade 100-200 mesh chloride form was obtained from Bio-Rad, Hercules, CA. A mixed nuclide source in a sealed 1.5 mL centrifuge tube used for high purity germanium detector (HPGe) measurements was prepared by Eckert & Ziegler Analytics (Atlanta, GA). 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) was obtained from Macrocyclics (Plano, TX) and Aluminum Si-60 TLC plates were obtained from Tech Sorbtech (Norcross, GA). ).

All other materials were purchased from Fisher Scientific (Hampton, NH) unless otherwise noted.

Natural Cr foil

As described in Pyles et al. 2021, Cr foils were produced on a large scale by electrodeposition of bulk Cr as previously reported in Wooten et al. 201511,13.

Natural Cr powder target

The Cr metal powder target was made by pressing 200-230 mg of natural Cr metal powder in 5 tons for 5 minutes using hydraulic press and 10 mm paint. These targets are 10 mm in diameter and 0.4-0.5 mm thick. Tantalum (Ta) sheet with 3N8 purity and 0.06 in thickness, was cut into 2.5 cm diameter coins and 0.5 mm deep divot was placed in the center to hold the Cr powder target. . Additionally, these targets had a divot for the Viton O-ring outside the target divot to prevent loss of target material. The target was wrapped with a 0.75 mm Aluminum (Al) degrader with a “push button” design to fit a 14 mm divot to cover the target and O-ring as shown in Figure 1A.

Figure 1
picture 1

Image of the predicted target configuration of the beam. (the) Cr metal powder target with Al “push button” degrader, (at) Cr2O3 goal, (C) electroplated Cr(III) target.

Targeted by Chromium oxide powder

52Cr2O3 done in comments.

$$^ {{{52}}} {\text{Cr }} + {\text{ 3HCl}} \to^{52} {\text{CrCl}}_{{3}} + {\text{ 3H }}^{ + } {; }^{52} {\text{CrCl}}_{{3}} + {\text{ 3NH}}_{{4}} {\text{OH}} \to^{{{52}}} { \text{Cr}}\left( {{\text{OH}}} \right)_{{3}} + {\text{ 3NH}}_{{4}} {\text{Cl }};{ 2}^ {{{52}}} {\text{Cr}}\left( {{\text{OH}}} \right)_{{3}} \to^{{{52}}} {\ text{Cr}}_{{2}} {\text{O}}_{{3}} + {\text{ 3H}}_{{2}} {\text{O}}$$

Using enriched 52Cr metal powder as starting material.

200-230 mg 52Cr was dissolved in 5 mL of 6 M hydrochloric acid (HCl) heated to 95 °C for about 30 minutes or until the product dissolved. 52CrCl3. About 10 mL of 7 M ammonium hydroxide was added 52CrCl3 solution to gas the material as 52Cr(OH)3. the 52Cr(OH)3 was centrifuged at 3000 rpm for 7 minutes or until the gas separated from the solution. The precipitate pellet was separated from the supernatant, and washed with MQ water. the 52Cr(OH)3 Heated at 200-250 ° C to obtain the final product 52Cr2O3. Then the 52Cr2O3 the powder was weighed and placed in an oven to dry at 250°C. The powder target was made by pressing 200-230 mg of 52Cr2O3 powder with a diameter of 10 mm ID dry pressure die set, to ensure the correct target shape, in 5 tons of 5 min using hydraulic machine to make the pellet pressure used for irradiations. These targets are 10 mm in diameter and 0.4-0.5 mm thick. The target was constructed as described in Section 1.3 with a Ta and Al “push button” support as shown in Figure 1B.

Electroplated Cr(III) target

Chromium chloride hexahydrate (CrCl3· 6H2O) was used as a source of chromium in the electrodeposition solution that was prepared according to the method previously described in Liang et al.14. A 20 × 150 mm limestone disposable culture tube modified to have two open ends was used for cell electrolysis. The plating diameter is 10 mm with a nominal thickness of 0.1-0.5 mm depending on the amount of Cr plated as shown in Figure 1C. Copper (Cu) or Gold (Au) plates with purity 5N5 and 5N, and a thickness of 0.75 mm were cut into coins 2.5 cm in diameter to be used as the support (cathode) and the A platinum rod was used as a circuit. anode suspended in solution. The electroplating equipment was connected to a DC power supply that used alligator clips to apply voltage to the platinum rod. (Figure 2) The voltage applied to the platinum rod and the electroplating solution was 3.8 V which gave an average current of 0.075 A. In addition, the targets were finally sealed with a 0.75 mm Al degrader those.

Figure 2
picture 2

An electrical device used for plating Cr metal from CrCl3 solution where the cathode is between the base plate and the plastic coin holder. The anode is the platinum rod that is found connected to the motor and suspended in CrCl3 labeling solution.

Definition of radiation

Retention and number of ions in matter (SRIM) was used to determine the energy of the proton beam on the target after annealing.15. All bombardments were performed on a TR-24 Cyclotron (Advanced Cyclotron Systems Inc). The beam below used the bombardment parameter improved by El Sayed et al. These target configurations were cleaned with a proton beam energy of 17.5 MeV in the degrader (12.8 MeV in the Cr target material) at 15 μA for 2-8 h. The proton beam stopped at the end of the amount they determined in each target system. The target was cooled by He gas in front of the target and the rear of the target was water cooled.

Characterization of the target by scanning electron microscope (SEM)

The electroplated targets were analyzed by SEM to determine the purity of the plated Cr. The SEM analysis was carried out with a SEM FEI Quanta 650 FEG with a secondary electron detector at an acceleration voltage of 16 kV for spectroscopy with an electron dispersive X-ray spectroscopy (EDAX) analyzer to to measure qualitatively the sample stoichiometry. SEM used xT microscope control software while EDAX used Teams software.

Cleaning methods

The purification procedure described below was adapted from Pyles et al. except for natural Cr foils that used the exact separation method described in Pyles et al.13. For the analysis, there were three columns consisting of 1 mL solid-phase extraction (SPE) tubes filled with AG1-X8 resin as follows: column 1 (C1) -300 mg, column 2 (C2) -200 mg and column 3 ( C3)—100 mg. A frit supplied with the SPE tubes was added on top of the AG1-X8 resin to prevent the resin bed from being disturbed by reagents entering during the cleaning process. The irradiated Cr target was dissolved in concentrated HCl, dissolved in 3% HCl in EtOH and loaded onto a column of AG1-X8 resin. Cr was purified by 3% HCl in ethanol. Mn was precipitated with 6 M HCl.

The corresponding procedure for the three-column chemical separation is described in Table 3 and Figure 3 .

Table 3 Chemical separation method for load sequence for three-column system for purification of 52Mn from cyclotron bombarded Cr13.
Figure 3
picture 3

Schematic diagram of a semi-automatic system designed for isolation 52Mn from chrome target device, valve control and syringe pump while syringes 1-6 are operated manually. B1-3: Levels 1–3; T1-3: 50 mL conical vials 1–3; C1-3: columns 1–3; V1-5: Valves 1–5; ABCD: 4 way valve; S1-6: Syringes 1–6; SP1-2: Syringe pump 1–2; FPV: final product vial. Modified from Pyles et al.13.

Gamma spectroscopy

After melting and dissolving the target, aliquots were collected from the undiluted solution. natCr and 52Cr is the target before and after cleaning. Samples were analyzed as described in Pyles et al.13.

Inductively coupled plasma-mass spectrometry (ICP-MS)

Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS, 7700 Series; Agilent, Santa Clara, CA) was used to evaluate the presence of Cr in the dissolved target material and the solution extracted from each column. Aliquots of each sample were taken and analyzed as described in Pyles et al.13.

Chemical chelation

To evaluate the chemical purity and apparent molar activity (AMA) of 52When the target natural chromium metal was produced, a chelation assay was performed as described by Graves et al.4. short 52MnCl2 was dried and resuspended in 0.1 M ammonium acetate, pH 4.5. A sample of DOTA (double layer 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) 1 mg/mL in 0.1 M ammonium acetate, pH 4.5 was prepared. 100 μL of buffered activity was added to each DOTA sample and incubated at 37 °C for 1 hour. The loading efficiency of the samples was evaluated by spotting 2 μL of each sample on an Aluminum TLC plate supported by Si-60. The plates were developed with 0.1 M HCl mobile phase, 52Mn-DOTA stopped at the beginning and was free 52Mn moved to the mobile phase.

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