N Production Via D- 3 He Fusion using a Water-Cooled IEC Cathode

Transcription

1 13 N Production Via D- 3 He Fusion using a Water-Cooled IEC Cathode Ben Cipiti 6 th U.S.-Japan IEC Workshop Tokyo, Japan October 20-21, 2003

2 Overview Experimental Objective To use beam-target D- 3 He reactions in the IEC device to produce medical isotopes Outline Previous Work ( 94m Tc Production) Isotope Production System Goals Water Target Experimental Setup Production Yield Discussion Future Work

3 Molybdenum Target Produced 1 nci 94m Tc (as Reported US-Japan 5) Moly Target Activation Spectrum (Background Subtracted) 511 kev ( 94m Tc) Counts (in 1 hour) kev Channel Number Embedded D- 3 He reactions at the cathode surface 14.7 MeV protons traveled into the molybdenum target 94m Tc produced from a (p,n) reaction on 94 Mo

4 Follow-up Runs Produced 2.8 nci & Verified the 52-minute Half Life m Tc Production Decay Plot Total Target Activity (nci) Production ~ 2.9 nci (Theoretical value based on experimental D- 3 He proton rates ~ 2.8 nci) Curve was fit with the 94m Tc decay constant = min Time after Shutdown (min)

5 Isotope Production System Goals Target must be robust to handle many runs The activated isotope should be able to be removed from the device quickly Target must withstand the high power input Rates must be maximized

6 Embedded Fusion Can Be Used To Produce 13 N From A Water Target D + D + 3 He He + D + p p p p 3 He He + D D D p p p + 3 p He 3 He p p p p 3 He p D p p p D 3 He He + p 3 He D p p Water 3 He Thin-Walled Stainless Steel Tube p 3 He 3 He + + D + 3 He He + D + D + 3 He He + Replace the cathode with a thin-walled stainless steel tube Embedded fusion occurs in the tube wall Half of the 14.7 MeV protons travel into the water: 16 O(p,α) 13 N

7 Water Target Setup HV Supply 3/4 BN Stalks Thin- Walled Stainless Steel Tube Ion Exchange Resin Pressure Relief Pump Cooling Line In NaI Detector Tube-in- Tube Heat Exchanger Cooling Line Out Water target must be cooled Water serves as both the cooling system and the material to be activated Primary water loop must be kept pure and ion free Ion exchange resin removes the 13 N ions

8 Water Target System Resin Exchange Column Thin Wall S.S. Tube Double Insulating Stalk Pump

9 Water Processing System High Voltage Pressure Relief Resin Exchange Column Tube-in- Tube Heat Exchanger

10 Current Configuration Achieved 4x10 6 p/s 85 kv, 30 ma 4.5E+06 Cooled Target 14.7 MeV Proton Production Run 863, , kv, 30 ma 4.0E+06 D- 3 He Proton Rate (p/s) 3.5E E E E E E E E Experiment Time (min)

11 Cooled Target Run Produced 1.5 nci 13 N at End of Bombardment 2 13 N Cooled Target Production Run Total Collected Activity (nci) Production ~ 1.5 nci Theoretical value based on experimental D- 3 He proton rates = 2.0 nci Curve was fit with the 13 N decay constant = s Time (s)

12 Methods to Increase the 13 N Yield Increase the run voltage At 150 kv, the proton fluence should be a factor of 15 greater than rates at 85 kv Increase the current Current is directly proportional to yield Increase the run time Up to 2-3 half-lives Increase the embedded number density Change tube material

13 Conclusion and Future Work Running the cooled water target at 85 kv for a short time produced 1.5 nci 13 N The cooled target setup satisfies the initial goals for a production system The next step is to improve the design for higher, sustained voltages In the future continuous counting of the rates during a run will be implemented