Measurements of Proton Measurements of Proton Induced Reaction Cross-Induced Reaction Cross-

Sections on Sections on natnatMo up to 35 Mo up to 35

MeV at MC-50 CyclotronMeV at MC-50 Cyclotron

ByByMayeen Uddin KhandakerMayeen Uddin Khandaker

Supervised by,Supervised by,Prof. Guinyun KimProf. Guinyun Kim

What is meant by Cross-section ?What is meant by Cross-section ? Basically, cross-section is nothing but the probability of Basically, cross-section is nothing but the probability of

interaction takes place between the incident beam particle & interaction takes place between the incident beam particle & the target nuclides.the target nuclides.

Another definition is that;Another definition is that; The geometrical area through which the interaction takes placeThe geometrical area through which the interaction takes place

. . Mathematically-Mathematically-A section formed by a airplane cutting A section formed by a airplane cutting

through an object, usually at right angles to an axis. 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 = 101 barn = 10−24−24 cm cm2 2

Why do we need to know the cross-Why do we need to know the cross-sectional data?sectional data?

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

What is the advantages of using proton What is the advantages of using proton beam over deuteron or helium?beam over deuteron or helium?

due to the lower stopping-power and larger due to the lower stopping-power and larger range than deuterons and helium range than deuterons and helium

Stopping power- It is the total energy lost per Stopping power- It is the total energy lost per path length by a charged particle.path length by a charged particle.

Why proton has larger range?Why proton has larger range?

Among all the charged particles Among all the charged particles 11HH11, , 22HH1 1 & & 44HeHe2 2 , proton carries the smaller mass. So, it , proton carries the smaller mass. So, it

can travel larger distances than others.can travel larger distances than others.

General purposes of activation General purposes of activation experiment:experiment: To produce medically important radioisotopesTo produce medically important radioisotopes

To know the To know the radiation & shielding effects of the investigated radiation & shielding effects of the investigated elementelement

To be acknowledged about the nuclear waste transmutation To be acknowledged about the nuclear waste transmutation and energy production.and energy production.

To be acknowledged of the elements as structural and To be acknowledged of the elements as structural and instrumental materials instrumental materials

To use the radioisotopes in dosimetry application, radiation To use the radioisotopes in dosimetry application, radiation therapy etc.therapy etc.

Why do we choose natural Why do we choose natural molybdenum as target material?molybdenum as target material?

Due to its use as structural materialDue 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 ( 2623Due to its very high melting point ( 262300C) C) Due to its use as refractory and corrosion resistant Due to its use as refractory and corrosion resistant

material in accelerator applications.material in accelerator applications. Due to the production of medically important Due to the production of medically important

radioisotopes like radioisotopes like 99m99mTc, Tc, 9999Mo, Mo, 9696Tc, Tc, 95m95mTc, Tc, 95g95gTc, Tc, 94m94mTc, Tc, 94g94gTc etc. Tc etc.

Objectives of this experiment:Objectives of this experiment:

to report on the measurement of excitation to report on the measurement of excitation functions for functions for natnatMo(p, xn)Mo(p, xn)97-x97-xTc, x= 1~4 and Tc, x= 1~4 and natnatMo(p, pn)Mo(p, pn)9696Nb nuclear reactions in the Nb nuclear reactions in the energy region up to 30 MeV.energy region up to 30 MeV.

to compare this experimental data with the to compare this experimental data with the previous published values. previous published values.

Experimental TechniqueExperimental Technique Preparation of samples (Preparation of samples (Special care was taken in Special care was taken in

preparation of uniform targets with known thickness).preparation of uniform targets with known thickness). Determination of samples activityDetermination of samples activity Using the order Using the order Al-Cu-Mo repeatedly, stacked Al-Cu-Mo repeatedly, stacked

( sandwiched) was formed.( sandwiched) was formed. where , Cuwhere , Cu Monitor foil Monitor foil AlAl Energy degrader & Monitor foil Energy degrader & Monitor foil

..The degradation of proton beam energy were The degradation of proton beam energy were calculated by using calculated by using SRIM-2003SRIM-2003 program. program.

The samples were then irradiated by 35 MeV The samples were then irradiated by 35 MeV external proton beam line of Cyclotron 50-MC external proton beam line of Cyclotron 50-MC at KIRAM, Seoul.at KIRAM, Seoul.

Beam diameter-0.1 cmBeam diameter-0.1 cm Beam current-100 nABeam current-100 nA Irradiation time- 8.3 mins. & 40 mins.Irradiation time- 8.3 mins. & 40 mins. The beam intensity was kept constant during The beam intensity was kept constant during

irradiation. irradiation. The activity of the produced radioisotopes of The activity of the produced radioisotopes of

the target and monitor foils were measured the target and monitor foils were measured continuously on the basis of their gamma continuously on the basis of their gamma radiation energy using HPGe detector.radiation energy using HPGe detector.

Data EvaluationData Evaluation The HPGe -detector was coupled with a 4096 multi-channel The HPGe -detector was coupled with a 4096 multi-channel

analyzer (MCA) with the associated electronics to determine analyzer (MCA) with the associated electronics to determine the photo peak-area of gamma ray spectra by using the photo peak-area of gamma ray spectra by using gamma gamma visionvision computer program. computer program.

The activity measurements were done after sufficient cooling The activity measurements were done after sufficient cooling time to complete the decay of most of the undesired short-time to complete the decay of most of the undesired short-lived activities to identify and separate complex gamma lines.lived activities to identify and separate complex gamma lines.

The detector-source distances were kept long enough (10~60 The detector-source distances were kept long enough (10~60 cm) to assure low dead time and point like geometry. cm) to assure low dead time and point like geometry.

The efficiency versus energy curve for the HPGe-detector was The efficiency versus energy curve for the HPGe-detector was drawn using the standard gamma-ray point sources (drawn using the standard gamma-ray point sources (133133Ba, Ba, 5757Co, Co, 6060Co, Co, 137137Cs, Cs, 5454Mn and Mn and 109109Cd) with known strength. Cd) with known strength.

The Mo targets and the Al & Cu monitor foils were measured The Mo targets and the Al & Cu monitor foils were measured in the same counting geometry with the same detector in the same counting geometry with the same detector calibrated with standard gamma-sources. calibrated with standard gamma-sources.

The cross- sections were deduced for the reactions The cross- sections were deduced for the reactions natnatMo(p, Mo(p, xn)xn)97-x97-xTc, x= 1~4 and Tc, x= 1~4 and natnatMo(p, pn)Mo(p, pn)9696Nb in the proton energy Nb in the proton energy range 5~30 MeV by using the well-known activation formula. range 5~30 MeV by using the well-known activation formula.

The decay data used in the calculation was taken from The decay data used in the calculation was taken from Browne Browne and Firestoneand Firestone book. book.

The threshold energies of reactions were calculated using the The threshold energies of reactions were calculated using the Los Alamos National Laboratory T-2 Nuclear Information Los Alamos National Laboratory T-2 Nuclear Information Service on the internet. Service on the internet.

The total uncertainties of the measured cross-section were The total uncertainties of the measured cross-section were calculated by using the uncertainty data obtained from the calculated by using the uncertainty data obtained from the gamma vision program. gamma vision program.

Results and DiscussionResults and Discussion

Excitation function of Excitation function of natnat Mo(p,xn) Mo(p,xn)96(m+g)96(m+g) Tc Tc

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M. Bonardi (2002) S. takacs (2002) M.S. Uddin (2004)Present Work Recommended

We measured the excitation function of We measured the excitation function of 96g96gTc Tc production by using the intense independent production by using the intense independent gamma line, 812.5 keV. gamma line, 812.5 keV.

It is a sum of three processes, It is a sum of three processes, 9696Mo(p, n) Mo(p, n) 96g96gTc Tc (Q= -3.79 MeV), (Q= -3.79 MeV), 9797Mo(p, 2n) Mo(p, 2n) 9696Tc (Q= -10.69 Tc (Q= -10.69 MeV), MeV), 9898Mo(p, 3n) Mo(p, 3n) 9696Tc (Q= -19.42 MeV). Tc (Q= -19.42 MeV).

Our results showed very good agreement with Our results showed very good agreement with the most latest data reported by Takacs et al. the most latest data reported by Takacs et al. (2002), M.S. Uddin et al.(2004) [16, 17]and (2002), M.S. Uddin et al.(2004) [16, 17]and the recommended values and this fact confirms the recommended values and this fact confirms the reliability of the measured cross-section the reliability of the measured cross-section values of values of 96g96gTc production. Tc production.

Excitation function of Excitation function of nat nat Mo(p,xn)Mo(p,xn)95g95g Tc Tc In order to calculate the production cross-In order to calculate the production cross-

section of section of 95g95gTc, we considered the gamma line Tc, we considered the gamma line 765.794 keV and also confirmed the result 765.794 keV and also confirmed the result with the 1073.713 keV gamma line with the 1073.713 keV gamma line

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Excitation function of Excitation function of nat nat Mo(p,xn)Mo(p,xn)95m95m Tc Tc The production cross-section of The production cross-section of 95m95mTc is Tc is

calculated with the analysis of 835.149 keV calculated with the analysis of 835.149 keV gamma peak. gamma peak.

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Excitation function of Excitation function of natnat Mo(p,xn) Mo(p,xn)94g94g Tc Tc The production cross-section of The production cross-section of 94g94gTc is Tc is

calculated with the analysis of 702.626 keV calculated with the analysis of 702.626 keV gamma peak.gamma peak.

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Excitation function of Excitation function of natnat Mo(p,xn) Mo(p,xn)9696 Nb Nb The production cross-section of The production cross-section of 9696Nb is Nb is

calculated with the analysis of 459.88 keV calculated with the analysis of 459.88 keV gamma peak.gamma peak.

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ConclusionsConclusions

Several authors reported the cross-sectional Several authors reported the cross-sectional values of the investigated radio nuclides. values of the investigated radio nuclides.

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

Although, the data reported by J.J. Hogan (1971) and Although, the data reported by J.J. Hogan (1971) and Lagunas-solar et al. (1991) are available in the Lagunas-solar et al. (1991) are available in the internet, we didn’t use their values for comparison internet, we didn’t use their values for comparison with our data because these values have a large with our data because these values have a large discrepancies with the recent published values.discrepancies with the recent published values.

However, we tried to our best in order to report a However, we tried to our best in order to report a reliable data set for the investigated radio nuclides in reliable data set for the investigated radio nuclides in the energy range 5-30 MeV & we do believe that we the energy range 5-30 MeV & we do believe that we have done our job successfully. have done our job successfully.

AcknowledgmentsAcknowledgments

The author would like to give special thanks to The author would like to give special thanks to the staffs of the Cyclotron Laboratories the staffs of the Cyclotron Laboratories (KIRAM, Seoul) for their cordial help in (KIRAM, Seoul) for their cordial help in performing the irradiations of the samples. performing the irradiations of the samples.

This research received financial support from This research received financial support from the MOST (Project Number M2-0409-00-the MOST (Project Number M2-0409-00-0001). 0001).

References:References:

1. Ziegler, J.F., Biersack, J.P., Littmark, U., SRIM 1. Ziegler, J.F., Biersack, J.P., Littmark, U., SRIM 2003 code, Version 96.xx. The stopping and range 2003 code, Version 96.xx. The stopping and range of ions in solids. Pergamon, New York.of ions in solids. Pergamon, New York.

2. E. Browne, R.B. Firestone, Table of Radioactive 2. E. Browne, R.B. Firestone, Table of Radioactive Isotopes, in: V.S. Shirley (ed.), Wiley, New York, Isotopes, in: V.S. Shirley (ed.), Wiley, New York, 1986.1986.

3. Reaction Q-values and thresholds, Los Alamos 3. Reaction Q-values and thresholds, Los Alamos National Laboratory, T-2 Nuclear Information National Laboratory, T-2 Nuclear Information Service. Available from< Service. Available from< http://t2.lanl.gov/data/qtool.htmlhttp://t2.lanl.gov/data/qtool.html>>

4. Monitor cross-section data Available at 4. Monitor cross-section data Available at < < http://www-nds.iaea.org/medical/cup62zn.htmlhttp://www-nds.iaea.org/medical/cup62zn.html>>

5. Takacs, S., Tarkanyi, F., Sonck, M., Hermanne, A., 2002. 5. Takacs, S., Tarkanyi, F., Sonck, M., Hermanne, A., 2002. Investigation of the Investigation of the nat nat Mo(p,xn) Mo(p,xn)96mg96mgTc nuclear reaction to Tc nuclear reaction to

monitor proton beams: new measurements and monitor proton beams: new measurements and consequences on the earlier reported data. Nucl. Instrum. consequences on the earlier reported data. Nucl. Instrum. Method Phy. Res. Method Phy. Res. B B 198, 183-196.198, 183-196.

6. Uddin, M.S., Hagiwara, M., Tarkanyi, F., Ditroi, F., Baba, 6. Uddin, M.S., Hagiwara, M., Tarkanyi, F., Ditroi, F., Baba, M., 2004. Experimental studies on the proton-induced M., 2004. Experimental studies on the proton-induced activation reactions of molybdenum in the energy range 22-activation reactions of molybdenum in the energy range 22-67 MeV. Applied Radiation and Isotopes 60 (2004) 911-67 MeV. Applied Radiation and Isotopes 60 (2004) 911-920.920.

7. Bonardi, M., Birattari, C., Groppi, F., Sabbioni, E., 2002. 7. Bonardi, M., Birattari, C., Groppi, F., Sabbioni, E., 2002. Thin-target excitation functions, cross-sections and Thin-target excitation functions, cross-sections and optimized thick-target yields for optimized thick-target yields for natnatMo(p, xn)Mo(p, xn)94g,95m,95g,96(m+g)94g,95m,95g,96(m+g) Tc nuclear reactions induced by protons from threshold up Tc nuclear reactions induced by protons from threshold up to 44 MeV. No Carrier Added radiochemical separation and to 44 MeV. No Carrier Added radiochemical separation and quality control. Applied Radiation and Isotopes 57 (2002) quality control. Applied Radiation and Isotopes 57 (2002) 617-635.617-635.