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Measurements of Proton Induced Reaction Cross-Sections on nat Mo up to 35 MeV at MC-50 Cyclotron

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. What is meant by Cross-section ?.

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Measurements of Proton Induced Reaction Cross-Sections on nat Mo up to 35 MeV at MC-50 Cyclotron

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  1. Measurements of Proton Induced Reaction Cross-Sections on natMo 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. • Another definition is that; 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. 1 barn = 10−24 cm2

  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.

  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 • Stopping power- It is the total energy lost per path length by a charged particle. • Why proton has larger range? Among all the charged particles 1H1, 2H1 & 4He2 , 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 know the radiation & shielding effects of the investigated element • To be acknowledged about the nuclear waste transmutation and energy production. • To be acknowledged of the elements as structural and instrumental materials • 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 low cost • Due to its good thermal and electrical conductivity • Due to its very high melting point ( 26230C) • Due to its use as refractory and corrosion resistant material in accelerator applications. • Due to the production of medically important radioisotopes like 99mTc, 99Mo, 96Tc, 95mTc, 95gTc, 94mTc, 94gTc etc.

  7. Objectives of this experiment: • to report on the measurement of excitation functions for natMo(p, xn)97-xTc, x= 1~4 and natMo(p, pn)96Nb nuclear reactions in the energy region up to 30 MeV. • 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). • Determination of samples activity • Using the order Al-Cu-Mo repeatedly, stacked ( sandwiched) was formed. where , Cu 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. • Beam diameter-0.1 cm • Beam current-100 nA • Irradiation time- 8.3 mins. & 40 mins. • 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.

  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 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 efficiency versus energy curve for the HPGe-detector was drawn using the standard gamma-ray point sources (133Ba, 57Co, 60Co, 137Cs, 54Mn and 109Cd) 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 cross- sections were deduced for the reactions natMo(p, xn)97-xTc, x= 1~4 and natMo(p, pn)96Nb 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 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.

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

  13. We measured the excitation function of 96gTc production by using the intense independent gamma line, 812.5 keV. • It is a sum of three processes, 96Mo(p, n) 96gTc (Q= -3.79 MeV), 97Mo(p, 2n) 96Tc (Q= -10.69 MeV), 98Mo(p, 3n) 96Tc (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 96gTc production.

  14. Excitation function of nat Mo(p,xn)95g Tc • In order to calculate the production cross-section of 95gTc, 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 • The production cross-section of 95mTc is calculated with the analysis of 835.149 keV gamma peak.

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

  17. Excitation function of nat Mo(p,xn)96 Nb • The production cross-section of 96Nb 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. • 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. • 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. • 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< 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)96mgTc nuclear reaction to 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 natMo(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.

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