**4. Conclusions**

152 Radioisotopes – Applications in Physical Sciences

Fig. 10. The comparison of the calculated cross section of 203Tl(p,3n)201Pb reaction with the

**18F** 1.83 h EC + β+ (100) 0.52 0.01795 Ep= 10 5

**57Co** 271.74 d EC + β+ (100) 122.06065 85.60 Ep= 15 5

**54Mn** 312.05d EC + β+ (100) 834.848 99.97 Ep= 20 10

**67Ga** 3.2617 d EC + β+ (100) 393.527 4.56 Ep= 30 15

**68Ga** 67.63m EC+ β+ (100) 1077.35 3 Ep= 15 5

**90Mo** 5.67h EC + β+ (100) 257.34 78 Ep= 55 45

**111In** 2.8047 d EC + β+ (100) 245.350 94.10 Ep= 25 15

**125Xe** 56.9s EC + β+ (100) 111.3 60.2 Ep= 35 25

**128Ba** 2.43d EC + β+ (100) 273.44 14.5 Ep= 70 50

**201Pb** 9.33 h EC+ β+ (100) 546.280 0.279 Ep= 30 20

Table 1. The decay data and optimum energy range for investigated radionuclides.

**(%) E� (keV) I��(%)** 

**Optimum Energy Range (MeV)** 

values reported in Ref. [7].

**radioisotopes Half life Mode of decay** 

**Producted** 

The new calculations on the excitation functions of 18O(p,n)18F, 57Fe(p,n)57Co, 57Fe(p,α)54Mn, 68Zn(p,2n)67Ga, 68Zn(p,n)68Ga, 93Nb(p,4n)90Mo, 112Cd(p,2n)111In, 127I(p,3n)125Xe ,133I(p,6n)128Ba and 203Tl(p,3n)201Pb reactions have been carried out using nuclear reaction models. Although there are some discrepancies between the calculations and the experimental data, in generally, the new evaluated hybrid and GDH model calculations (with ALICE/ASH) are good agreement with the experimental data above the incident proton energy with 5-100 MeV in Figs. 1-10. While the Weisskopf-Ewing model calculations are only in agreement with the measurements for lower incident proton energy regions, hybrid model calculations are in good harmony with the experimental data for higher incident proton energy regions. Some nuclei used in this study were examined and compared in previous paper written by Tel et al.[13,14]. Detailed informations can be found in these papers. And also new developed semi-empirical formulas for proton incident reaction cross-sections can be found in Ref. [27,28].

When Comparing the experimental data and theoretical calculations, the production of 18F,57Co, 54Mn, 67,68Ga, 90Mo, 111In, 125Xe , 128Ba and 201Pb radioisotopes can be employed at a medium-sized proton cyclotron since the optimum energy ranges are smaller than 50 MeV, except for 128Ba. We gave the optimum energy range and the decay data for the investigated radionuclides in Table 1.

### **5. References**


**9** 

*USA* 

**History of Applications of Radioactive** 

**Sources in Analytical Instruments for** 

*Laboratory for Astrophysics and Space Research, Enrico Fermi Institute,* 

Space age started with the launch of Sputnik-1 more than 50 years ago. Since then we have visited all the planets, some of them many times with very capable spacecrafts that are equipped with sophisticated payload that are returning significant information about the composition, physical condition of their surfaces and atmospheres and much more information. However, at the beginning of the space age, there were no techniques and instruments available to be used in space and had to be invented, designed, built and tested for the harsh environmental conditions in space. For the first analytical instruments in space, transuranium artificial radioisotopes produced in the national laboratories, proved to be very useful for applications in space. In early sixties Anthony Turkevich and his group at the University of Chicago applied a novel technique -- the Rutherford backscattering -- that is based on the interaction of the alpha particles with matter, to devise an instrument to obtain in-situ the chemical composition of the lunar surface [1]. In addition to measuring the backscattered alpha particles, the instrument also measures the proton energy spectra derived from the (α,p) reaction of the alpha particles with some light elements in the analyzed sample. Since the bombardment of a sample with a beam of alpha particles and xrays from the same source also produces specific characteristic x-rays that results in additional compositional information, an additional x-ray detector was added to the ASI instrument to detect the produced x-rays. Based on the successful performance of this instrument on the lunar missions, more advanced and miniaturized versions complimented with an x-ray mode were developed and used in many NASA, ESA and Russian missions to

**1. Introduction** 

several planetary bodies.

**2. The alpha scattering instrument for the lunar missions** 

The technique of alpha backscattering for obtaining the chemical composition of planetary bodies was described for the first time and in detail by A. Turkevich, 1961[1], 1968[2]; Patterson et al., 1965[3]; Economou et al., 1970[4], 1973[5]. The compositional information is obtained from the energy spectra of scattered alpha particles and protons generated in (α,p) reactions of alpha particles with the matter in the analyzed sample. As it is shown in Fig. 1, a

**Planetary Exploration** 

Thanasis E. Economou

*University of Chicago, Chicago,* 

