1. Measurements of Proton Induced Reaction Cross- Sections on nat Mo up to 35 MeV at MC-50 Cyclotron By Mayeen Uddin Khandaker Supervised by, Prof. Guinyun Kim

2. What is meant by Cross-section ? Basically, cross-section is nothing but the probability of interaction takes place between the incident beam particle & the target nuclides. Basically, cross-section is nothing but the probability of interaction takes place between the incident beam particle & the target nuclides. Another definition is that; Another definition is that; The geometrical area through which the interaction takes place The geometrical area through which the interaction takes place. Mathematically- A section formed by a airplane cutting through an object, usually at right angles to an axis. The unit of cross-section is called barn. The unit of cross-section is called barn. 1 barn = 10 −24 cm 2 1 barn = 10 −24 cm 2

3. Why do we need to know the cross- sectional data? In general, cross-sections means the excitation function of the target nuclei/material with respect to the incident beam energy. So, in order to use the target material in any nuclear devices or any sophisticated devices ( i.e., using as structural & instrumental materials), we need to know the interaction behavior/properties of the material - & this properties can be known from cross-sectional data. This is the basic need of knowing the cross-sectional data. In general, cross-sections means the excitation function of the target nuclei/material with respect to the incident beam energy. So, in order to use the target material in any nuclear devices or any sophisticated devices ( i.e., using as structural & instrumental materials), we need to know the interaction behavior/properties of the material - & this properties can be known from cross-sectional data. This is the basic need of knowing the cross-sectional data.

4. What is the advantages of using proton beam over deuteron or helium? due to the lower stopping-power and larger range than deuterons and helium due to the lower stopping-power and larger range than deuterons and helium Stopping power- It is the total energy lost per path length by a charged particle. Stopping power- It is the total energy lost per path length by a charged particle. Why proton has larger range? Why proton has larger range? Among all the charged particles 1 H 1, 2 H 1 & 4 He 2, proton carries the smaller mass. So, it can travel larger distances than others. Among all the charged particles 1 H 1, 2 H 1 & 4 He 2, proton carries the smaller mass. So, it can travel larger distances than others.

5. General purposes of activation experiment: To produce medically important radioisotopes To produce medically important radioisotopes To know the radiation & shielding effects of the investigated element To know the radiation & shielding effects of the investigated element To be acknowledged about the nuclear waste transmutation and energy production. To be acknowledged about the nuclear waste transmutation and energy production. To be acknowledged of the elements as structural and instrumental materials To be acknowledged of the elements as structural and instrumental materials To use the radioisotopes in dosimetry application, radiation therapy etc. To use the radioisotopes in dosimetry application, radiation therapy etc.

6. Why do we choose natural molybdenum as target material? Due to its use as structural material Due to its use as structural material Due to its low cost Due to its low cost Due to its good thermal and electrical conductivity Due to its good thermal and electrical conductivity Due to its very high melting point ( 2623 0 C) Due to its very high melting point ( 2623 0 C) Due to its use as refractory and corrosion resistant material in accelerator applications. Due to its use as refractory and corrosion resistant material in accelerator applications. Due to the production of medically important radioisotopes like 99m Tc, 99 Mo, 96 Tc, 95m Tc, 95g Tc, 94m Tc, 94g Tc etc. Due to the production of medically important radioisotopes like 99m Tc, 99 Mo, 96 Tc, 95m Tc, 95g Tc, 94m Tc, 94g Tc etc.

7. Objectives of this experiment: to report on the measurement of excitation functions for nat Mo(p, xn) 97-x Tc, x= 1~4 and nat Mo(p, pn) 96 Nb nuclear reactions in the energy region up to 30 MeV. to report on the measurement of excitation functions for nat Mo(p, xn) 97-x Tc, x= 1~4 and nat Mo(p, pn) 96 Nb nuclear reactions in the energy region up to 30 MeV. to compare this experimental data with the previous published values. to compare this experimental data with the previous published values.

8. Experimental Technique Preparation of samples (Special care was taken in preparation of uniform targets with known thickness). Preparation of samples (Special care was taken in preparation of uniform targets with known thickness). Determination of samples activity Determination of samples activity Using the order Al-Cu-Mo repeatedly, stacked ( sandwiched) was formed. Using the order Al-Cu-Mo repeatedly, stacked ( sandwiched) was formed. where, Cu  Monitor foil where, Cu  Monitor foil Al  Energy degrader & Monitor foil Al  Energy degrader & Monitor foil. The degradation of proton beam energy were calculated by using SRIM-2003 program.

9. The samples were then irradiated by 35 MeV external proton beam line of Cyclotron 50-MC at KIRAM, Seoul. The samples were then irradiated by 35 MeV external proton beam line of Cyclotron 50-MC at KIRAM, Seoul. Beam diameter-0.1 cm Beam diameter-0.1 cm Beam current-100 nA Beam current-100 nA Irradiation time- 8.3 mins. & 40 mins. Irradiation time- 8.3 mins. & 40 mins. The beam intensity was kept constant during irradiation. The beam intensity was kept constant during irradiation. The activity of the produced radioisotopes of the target and monitor foils were measured continuously on the basis of their gamma radiation energy using HPGe detector. The activity of the produced radioisotopes of the target and monitor foils were measured continuously on the basis of their gamma radiation energy using HPGe detector.

10. Data Evaluation The HPGe -detector was coupled with a 4096 multi-channel analyzer (MCA) with the associated electronics to determine the photo peak-area of gamma ray spectra by using gamma vision computer program. The HPGe -detector was coupled with a 4096 multi-channel analyzer (MCA) with the associated electronics to determine the photo peak-area of gamma ray spectra by using gamma vision computer program. The activity measurements were done after sufficient cooling time to complete the decay of most of the undesired short- lived activities to identify and separate complex gamma lines. The activity measurements were done after sufficient cooling time to complete the decay of most of the undesired short- lived activities to identify and separate complex gamma lines. The detector-source distances were kept long enough (10~60 cm) to assure low dead time and point like geometry. The detector-source distances were kept long enough (10~60 cm) to assure low dead time and point like geometry. The efficiency versus energy curve for the HPGe-detector was drawn using the standard gamma-ray point sources ( 133 Ba, 57 Co, 60 Co, 137 Cs, 54 Mn and 109 Cd) with known strength. The efficiency versus energy curve for the HPGe-detector was drawn using the standard gamma-ray point sources ( 133 Ba, 57 Co, 60 Co, 137 Cs, 54 Mn and 109 Cd) with known strength.

11. The Mo targets and the Al & Cu monitor foils were measured in the same counting geometry with the same detector calibrated with standard gamma-sources. The Mo targets and the Al & Cu monitor foils were measured in the same counting geometry with the same detector calibrated with standard gamma-sources. The cross- sections were deduced for the reactions nat Mo(p, xn) 97-x Tc, x= 1~4 and nat Mo(p, pn) 96 Nb in the proton energy range 5~30 MeV by using the well-known activation formula. The cross- sections were deduced for the reactions nat Mo(p, xn) 97-x Tc, x= 1~4 and nat Mo(p, pn) 96 Nb in the proton energy range 5~30 MeV by using the well-known activation formula. The decay data used in the calculation was taken from Browne and Firestone book. The decay data used in the calculation was taken from Browne and Firestone book. The threshold energies of reactions were calculated using the Los Alamos National Laboratory T-2 Nuclear Information Service on the internet. The threshold energies of reactions were calculated using the Los Alamos National Laboratory T-2 Nuclear Information Service on the internet. The total uncertainties of the measured cross-section were calculated by using the uncertainty data obtained from the gamma vision program. The total uncertainties of the measured cross-section were calculated by using the uncertainty data obtained from the gamma vision program.

12. Results and Discussion Excitation function of nat Mo(p,xn) 96(m+g) Tc Excitation function of nat Mo(p,xn) 96(m+g) Tc

13. We measured the excitation function of 96g Tc production by using the intense independent gamma line, 812.5 keV. We measured the excitation function of 96g Tc production by using the intense independent gamma line, 812.5 keV. It is a sum of three processes, 96 Mo(p, n) 96g Tc (Q= -3.79 MeV), 97 Mo(p, 2n) 96 Tc (Q= -10.69 MeV), 98 Mo(p, 3n) 96 Tc (Q= -19.42 MeV). It is a sum of three processes, 96 Mo(p, n) 96g Tc (Q= -3.79 MeV), 97 Mo(p, 2n) 96 Tc (Q= -10.69 MeV), 98 Mo(p, 3n) 96 Tc (Q= -19.42 MeV). Our results showed very good agreement with the most latest data reported by Takacs et al. (2002), M.S. Uddin et al.(2004) [16, 17]and the recommended values and this fact confirms the reliability of the measured cross-section values of 96g Tc production. Our results showed very good agreement with the most latest data reported by Takacs et al. (2002), M.S. Uddin et al.(2004) [16, 17]and the recommended values and this fact confirms the reliability of the measured cross-section values of 96g Tc production.

14. Excitation function of nat Mo(p,xn) 95g Tc Excitation function of nat Mo(p,xn) 95g Tc In order to calculate the production cross- section of 95g Tc, we considered the gamma line 765.794 keV and also confirmed the result with the 1073.713 keV gamma line In order to calculate the production cross- section of 95g Tc, we considered the gamma line 765.794 keV and also confirmed the result with the 1073.713 keV gamma line

15. Excitation function of nat Mo(p,xn) 95m Tc Excitation function of nat Mo(p,xn) 95m Tc The production cross-section of 95m Tc is calculated with the analysis of 835.149 keV gamma peak. The production cross-section of 95m Tc is calculated with the analysis of 835.149 keV gamma peak.

16. Excitation function of nat Mo(p,xn) 94g Tc Excitation function of nat Mo(p,xn) 94g Tc The production cross-section of 94g Tc is calculated with the analysis of 702.626 keV gamma peak. The production cross-section of 94g Tc is calculated with the analysis of 702.626 keV gamma peak.

17. Excitation function of nat Mo(p,xn) 96 Nb Excitation function of nat Mo(p,xn) 96 Nb The production cross-section of 96 Nb is calculated with the analysis of 459.88 keV gamma peak. The production cross-section of 96 Nb is calculated with the analysis of 459.88 keV gamma peak.

18. Conclusions Several authors reported the cross-sectional values of the investigated radio nuclides. Several authors reported the cross-sectional values of the investigated radio nuclides. We compared our measured data only the data reported by the following authors; M.Bonardi et al (2002), Takacs et al. (2002), M.S. Uddin et al. (2004). Because, these authors did their experiments in recent time and our results showed a good agreement with their reported values for all of the investigated radio nuclides. We compared our measured data only the data reported by the following authors; M.Bonardi et al (2002), Takacs et al. (2002), M.S. Uddin et al. (2004). Because, these authors did their experiments in recent time and our results showed a good agreement with their reported values for all of the investigated radio nuclides.

19. Although, the data reported by J.J. Hogan (1971) and Lagunas-solar et al. (1991) are available in the internet, we didn’t use their values for comparison with our data because these values have a large discrepancies with the recent published values. Although, the data reported by J.J. Hogan (1971) and Lagunas-solar et al. (1991) are available in the internet, we didn’t use their values for comparison with our data because these values have a large discrepancies with the recent published values. However, we tried to our best in order to report a reliable data set for the investigated radio nuclides in the energy range 5-30 MeV & we do believe that we have done our job successfully. However, we tried to our best in order to report a reliable data set for the investigated radio nuclides in the energy range 5-30 MeV & we do believe that we have done our job successfully.

20. Acknowledgments The author would like to give special thanks to the staffs of the Cyclotron Laboratories (KIRAM, Seoul) for their cordial help in performing the irradiations of the samples. The author would like to give special thanks to the staffs of the Cyclotron Laboratories (KIRAM, Seoul) for their cordial help in performing the irradiations of the samples. This research received financial support from the MOST (Project Number M2-0409-00- 0001). This research received financial support from the MOST (Project Number M2-0409-00- 0001).

21. References: 1. Ziegler, J.F., Biersack, J.P., Littmark, U., SRIM 2003 code, Version 96.xx. The stopping and range of ions in solids. Pergamon, New York. 2. E. Browne, R.B. Firestone, Table of Radioactive Isotopes, in: V.S. Shirley (ed.), Wiley, New York, 1986. 3. Reaction Q-values and thresholds, Los Alamos National Laboratory, T-2 Nuclear Information Service. Available from 3. Reaction Q-values and thresholds, Los Alamos National Laboratory, T-2 Nuclear Information Service. Available from http://t2.lanl.gov/data/qtool.html 4. Monitor cross-section data Available at http://www-nds.iaea.org/medical/cup62zn.html

22. 5. Takacs, S., Tarkanyi, F., Sonck, M., Hermanne, A., 2002. Investigation of the nat Mo(p,xn) 96mg Tc nuclear reaction to monitor proton beams: new measurements and consequences on the earlier reported data. Nucl. Instrum. Method Phy. Res. B 198, 183-196. monitor proton beams: new measurements and consequences on the earlier reported data. Nucl. Instrum. Method Phy. Res. B 198, 183-196. 6. Uddin, M.S., Hagiwara, M., Tarkanyi, F., Ditroi, F., Baba, M., 2004. Experimental studies on the proton-induced activation reactions of molybdenum in the energy range 22- 67 MeV. Applied Radiation and Isotopes 60 (2004) 911-920. 7. Bonardi, M., Birattari, C., Groppi, F., Sabbioni, E., 2002. Thin-target excitation functions, cross-sections and optimized thick-target yields for nat Mo(p, xn) 94g,95m,95g,96(m+g) Tc nuclear reactions induced by protons from threshold up to 44 MeV. No Carrier Added radiochemical separation and quality control. Applied Radiation and Isotopes 57 (2002) 617-635.