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The thermal-neutron capture cross sections (σ0,m and σ0,g) and resonance integrals (I 0,m and I 0,g) leading to the isomeric and ground states of 81Se were measured by the activation method. Samples of high-purity (99.99%) selenium oxide were irradiated in a rotary specimen rack of the research reactor of Rikkyo University. Wires of Co/Al and Au/Al alloys, which have different sensitivities to neutrons in the thermal and epithermal energy regions, were irradiated to monitor the thermal neutron fluxes and the epithermal components at the same position of the rotary specimen rack. The cadmium-shielded samples were also irradiated to obtain the cadmium ratio and the resonance integrals (I 0,m and I 0,g). A high-purity Ge detector was used to measure the γ-rays emitted from the irradiated samples and wires, and reaction rates were calculated from γ-ray yields. On the basis of Westcott's convention, the cross sections were obtained as follows: σ0,m = 0.057 ± 0.003 b and I 0,m = 0.186 ± 0.014 b leading to 81mSe...

The thermal neutron capture cross section (σ0) and the resonance integral (I 0)of 237Np have been measured by an activation method to supply basic data for the study of transmutation of nuclear waste. The neutron irradiation of 237Np samples have been done at the Research Reactor Institute, Kyoto University (KUR). Samples of 237Np were irradiated between two Cd sheets or without a Cd sheet. Since 237Np has a strong resonance at the energy of 0.49 eV, the Cd cutoff energy was adjusted at 0.358 eV (thickness of the Cd sheets: 0.125 mm). A high purity Ge detector was employed for activity measurement. The reaction rate to produce 238Np from 237Np was analyzed by the Westcott's convention. Results obtained were 141.7±5.4 barns for σ0 and 862±51 barns for I 0 above 0.358 eV of 273Np. By setting the Cd cut-off energy at 0.358 eV considering the resonance at 0.49 eV, a smaller value of σ0 was obtained in this work than the values reported by the previous authors.

In order to develop a neutron flux monitor for long-term neutron irradiation, the thermal neutron(2,200 m/s neutron) capture cross section (≤σ0) and the resonance integral (I 0)of the 109Ag(n,γ)110mAg reaction were measured by the activation and γ-ray spectroscopic methods. Silver foils were irradiated with and without a Cd shield capsule at the Rikkyo Research Reactor. The Co/A1 and Au/A1 alloy wires were irradiated together with silver foils in order to monitor the thermal neutron flux and the fraction of the epi-thermal neutron part (Westcott's index). A high purity Ge detector was used for the γ-ray measurements of the irradiated samples. The σ0 and the I 0 of the 109Ag(n,γ)110mAg reaction are 4.12±0.10 b and 67.9±3.1 b, respectively. The σ0 is 12% smaller than the tabulated one (4.7±0.2 b). On the other hand, the I 0 is in agreement with the tabulated one (72.3±4.0 b) within the limits of error.

Thermal neutron capture cross sections (σ0) and resonance integrals (I0)of the 90Sr(n, γ)91Sr and 166mHo(n, γ)I67Ho reactions were measured with an activation method to provide fundamental data for research on nuclear transmutation methods of radioactive wastes.

The thermal neutron capture cross section (a0) and the resonance integral (I0) of 166mHo have been measured as data for the transmutation of nuclear waste. Samples of 166mHo were made by the neutron irradiation of 165Ho. Two metallic foils of 165Ho were irradiated for 2 weeks and two others for 3 weeks at the Kyoto University Reactor. A high purity Ge detector was employed for activity measurement. The samples irradiated were cooled for 3 months to reduce the activity of 166gHo. One of the samples irradiated for 2 weeks was irradiated again with Cd cover sheets and the other one without a Cd cover sheet. For the samples irradiated for 3 weeks, the same irradiation was performed. The 167Hon uclei were produced at the second irradiation via the neutron capture of 166mHo and the double neutron capture of 165Ho. The amount of 167Ho via the double capture was estimated from the difference between the data of 2 week irradiation and 3 week irradiation, and corrected. The reaction rate to produce 167Ho from 166mH...

To precisely determine emission probabilities of γ rays of 100Ru, β-γ coincidence measurements have been performed. A thin plastic scintillator was used to detect f rays emitted from the ground state of 100Tc produced by thermal neutron capture reaction of99 Tc, while γ rays de-exciting the excited states of 100Ru populated via the β decays were detected using a high-purity germanium detector. In the data analysis, ratios of counting rates of f rays in coincidence with one of the 100Ru γ rays to that of f-ray singles were deduced at several finite β-ray detection threshold energies. The ratios at the zero threshold energy were then deduced by extrapolating the ones at finite threshold energies to take the effect of cascading γ rays into account. From the ratios at the zero threshold energy, the emission probabilities of 539 and 591 keV γ rays of 100Ru, which are emitted following the β decay of 100Tc, were obtained to be 6.6±0.5% and 5.5±0.3%, respectively. By following the decay of the two γ rays, half-l...

For precise determination of γ-ray emission probabilities of short-lived nuclides whose half-lives are less than a few minutes, a β-γ coincidence measurement system has been developed which uses a plastic scintillator as a β-ray detector. The system was applied to a measurement of the absolute β-ray emission probability of 1,779keV β ray in 28A1 (Ti/2=2.24min), whose γ-ray emission probability is well known. The uncertainty of the measured γ-ray emission probability was smaller than 2%. Performance of the β-γ coincidence system has been demonstrated for a short-lived nuclide, and the details of the corrections have been analyzed.

In order to obtain precise data of the neutron capture cross section of the reaction 137Cs(n, γ)138Cs, the production probability of isomer state 138mCs was measured in this work. Targets of about 0.37MBq 137Cs were irradiated for 3 min in. the pneumatic tube facility (Pn-3) of Kyoto University Reactor (KUR). The 1,436 keV gamma;-ray emitted from both of 138gCs and 138mCs was measured. A ratio of the production probability between 138gCs and 138mCs was deduced from time dependence of peak counts of 1,436 keV γ-ray by making use of difference of half-lives of 138gCs (33.41 min) and 138mCs (2.91 min). The production probability of 138mCs was obtained as 0.75plusmn;0.18 and this value revised the effective cross section upwards by 9plusmn;2percnt;. The effective cross section o and the thermal neutron capture cross section σo were obtained as o=0.29±0.02 b and σ=0.27±0.03b with taking into account the production of 138mCs.

The measurements of the thermal neutron (2,200 m/s neutron) cross section (σ0) and the resonance integral (I 0) of the 133Cs(n, γ;) reaction were performed by an activation method to obtain fundamental data for research on the transmutation of nuclear wastes. The cross sections for the formations of the isomeric state 134mCs and the ground state 134mCs were measured respectively by following the behavior of the γ-ray counting rate after the irradiation. The thermal neutron capture cross sections and the resonance integrals of the 133Cs(n, γ) reaction were determined to be 2.70±0.13 b and 23.2±1.8 b for the formation of the isomeric state 134mCs, and 26.3±1.0 b and 275±16 b for the formation of the ground state of 134gCs. The results for the reaction 133Cs(n, γ)134m+gCs were 29.0±l.0 b and 298±16 b, respectively. As for the thermal neutron capture cross section for the formation of 134m+gCs, the evaluated value (29.00 b) of JENDL-3.2 agreed with the present result. The reported value by Baerg et al. was in...

The measurement of effective neutron capture cross section( ) of 134Cs was carried out with a method using a triple neutron capture reaction,133Cs(n, γ)134Cs(n,γ)135Cs(n, γ)136Cs. The target used for the experiment was natural cesium(133Cs), and was irradiated for 23 days and 17 hours in the reactor JRR-3 at Japan Atomic Energy Research fnstitute(JAERI). The neutron field of the reactor was monitored by Au/Al and Co/Al alloy wires. A high purity Ge detector was employed for the measurement of γ-rays from the irradiated target and monitor wires. Gamma-rays emitted in the decay of 134Cs and 136Cs nuclides induced by single and triple neutron capture reactions of 133Cs were seen at the energies of 563, 569. 605, 796, 802, 819, 1,039, 1,048, 1,168 and 1,235 keV. Decays of the 819 and the 1,048 keV γ-ray intensities were followed; it was confirmed that these γ-rays originated in the 136Ba, the decay product of 136Cs. Data obtained were analyzed with values of neutron capture cross sections of 133Cs and 135Cs. ...

The thermal neutron (2,200 m/s neutron) capture cross section (σ0) and the resonance integral (I 0) of the reaction 127I(n, γ)128I were obtained. The targets of the iodine were irradiated within and without a cadmium capsule at Rikkyo University Research Reactor. Characteristic features of neutron field were monitored by Co/Al and Au/Al wires. Gamma-rays from the irradiated targets were measured by a high purity Ge detector. The γ-ray spectra were taken successively and the decay of peak-area counts of the 443 keV γ-ray of 128I was followed. A half-life of 128I obtained was 24.72±0.03 min. The σ0 and I 0 of the reaction 127I(n, γ)128I were deduced from the analysis of obtained γ-ray spectra according to the Westcott's convention and were 6.40±0.29 barns and 162±8 barns, respectively. The previous measurements of the σ0 and I 0 of the reaction 127I(n, γ)128I were reviewed and differences between the present values and the previous results were discussed with special emphasis on the experimental results by ...

To determine the cross sections of the135Cs(n,γ)136Cs reaction, a sample of135Cs included in a “standardized solution” of137Cs was used as a target and irradiated in a reactor. The ratio of the atom number of135Cs to that of137Cs was determined to be 0.89±0.03 with a quadrupole mass spectrometer. The thermal cross section and the resonance integral measured in this study were determined to be 8.3±0.3 and 38.1±2.6 b respectively.

A Knudsen-cell-based quadrupole mass analyzer has been developed for the analysis of a small amount of RI sample. To achieve a high signal/noise ratio, a continuous dynode electron multiplier was installed at the end of the mass filter and was operated in a pulse counting mode. Furthermore, the cylindrical shape molecular trap was set around the mass analyzer to reach high degree of vacuum and to reduce the RI contamination area in the apparatus. The isotope ratio of 135Cs/137Cs samples has been measured to demonstrate the performance of the mass analyzer. Taking the advantage of the Knudsen-cell's precise controllability over temperature, the contribution of the isobar 137Ba was successfully removed in the mass spectrum of cesium. With samples containing about 0.3μg 137Cs and almost the same amount of 135Cs, the isotope ratio measurement with the total error of 3% has been achieved. The molecular trap was also shown to be effective to reduce the contamination area in the apparatus.

The thermal neutron (2,200 m/s neutron) capture cross section (σ0) and the resonance integral (I 0) of the reaction 135Cs(n, γ)136Cs were measured by means of an activation method to obtain fundamental data for research on the transmutation of nuclear waste. Targets of radioactive cesium, which include 135Cs and 137Cs as well as stable 133Cs, were irradiated with reactor neutrons within or without a Cd shield case. The Co/Al and Au/Al alloy wires as activation detectors were irradiated together with cesium samples to monitor the neutron flux and the fraction of the epithermal part (Westcott's index). A high purity Ge detector was used for the γ-ray measurements. The 137Cs nuclide was used as a tracer of 135Cs, since 135Cs decays through β-transition, but does not emit γ-rays. The ratio of the number of nuclei of 135Cs to that of 137Cs in the target was measured with a quadrupole mass spectrometer. This ratio and the ratio of activity of 136Cs to that of 137Cs in the irradiated target were used for deducti...

The effect of sintering aids on the tribological behavior of three kinds of hot-pressed Si3N4 ceramics sliding on itself in water was investigated at 120 °C under saturated vapor pressure of 0.1 MPa. At lower sliding speeds, the friction coefficients and specific wear rates of MgO + Al2O3-doped Si3N4 (SN-1 — were larger than those of Y2O3+Al2O3-doped materials (SN-2 and SN-3), and the wear behavior for all samples was mainly controlled by the reaction to produce NH3. These phenomena are probably caused by the contact stress on the asperities formed by the dissolution of the grain boundaries, because the intergranular layers for the SN-1 sample were easier to dissolve than those for the other samples. At higher sliding speeds above 0.4 m s−1, the friction coefficients and specific wear rates decreased in order of SN-3, SN-1 and SN-2. The wear properties were governed by the oxidation and microfracture of the Si3N4 substrate and may be related to the flat oxide film formed on the worn surface of SN-1 and the inferior oxidation resistance of Y10(SiO4)6N2 existing as the secondary phase in SN-3.

The effects of temperature and sliding speed on the tribological behavior of a SiC ceramic by sliding on the same material in deoxygenated water were investigated from room temperature to 300°C under the corresponding saturated vapor pressures. The friction coefficient and specific wear rates of both plates and disks increased at elevated temperatures at all sliding speeds, but decreased with increasing sliding speed at 120° and 300°C. Fine mirrorlike worn surfaces were observed without wear debris under all sliding conditions. The wear mechanism appears to consist of hydrothermal oxidation of SiC and dissolution of reaction products such as silica.

The effects of sliding speed and dissolved oxygen on the tribological behavior of Si[sub 3]N[sub 4] sliding on itself in water were investigated to room temperature and at 120 C saturated vapor pressure. The friction coefficients and specific wear rates at 120 C were much larger than those at room temperature and had a minimum at about 0.4 m/s, whereas the specific wear rate of the disk increased with increasing the sliding speed. The wear rate at lower sliding speeds in water at 120 C is considered to be primarily controlled by the increase of the contact stress on the asperities which are formed by the dissolution of grain boundaries of the Si[sub 3]N[sub 4] ceramic and the subsequent dissolution of the silica layer of the reaction products. However, the wear rate at higher sliding speeds is governed by the direct oxidation and microfracture of the Si[sub 3]N[sub 4] substrate. The tribochemical reaction to product NH[sub 3] mainly occurred at all sliding conditions in water at room temperature and 120 C, and the reaction to produce H[sub 2] gas appeared slightly only at the slidings speeds above 0.4 m/s at 120 C. The tribological behavior was independent of dissolved oxygenmore » concentration for all sliding conditions in water at room temperature and 120 C.« less

To obtain fundamental data for the research of the transmutation of nuclear waste, the thermal neutron cross section and the resonance integral of the reaction 137Cs(n, γ)138Cs have been measured by means of a modified Cd-ratio technique. Targets of about 0.4 MBq 137Cs were irradiated with neutrons in the JRR-4 swimming pool reactor by using a pneumatic tube equipped with a movable Cd shield, and neutron fluxes and their epithermal neutron fractions were monitored with activation detectors (Co/Al and Au/Al) whose sensitivity to epithermal neutrons differed from each other. After irradiation, the 137Cs samples were purified chemically and their γ-ray spectra were measured with a high purity Ge detector. The resulting yields of 138Cs for different neutron spectra and the neutron flux data have yielded that the thermal neutron cross section (for 2,200 m/s neutrons) is 0.25±0.02b and the resonance integral 0.36±0.07b. The results are consistent with the effective cross section (σ=0.250±0.013b) of our...

The PIXE analysis of atmospheric samples collected over Hungary and Japan has been made to investigate characteristic features of the samples of Hungary and Japan, and to compare them. Samples were collected at Budapest, Debrecen, Szerencs, Palhaza in Hungary, and at Tokyo, Noma coast Aichi, Obara-mura Aichi (rural district), Mt. Rokko, in Japan. The PIXE analysis of the samples was made using a 2 MeV proton beam from a Van de Graaff accelerator at Nagoya University. Differences, specially in the concentration of lead, between samples collected in Hungary and Japan were observed.

For promotion of nuclear science and engineering research, examinations were made on the possibilities and necessary measures to extend joint research at international level. The present article is a summary of the reports of investigations performed during FY 1986 through 1991 by the Special Committee of the AESJ for Feasibility Study on International Cooperation for Promotion of Nuclear Science and Engineering Research, under contract with Science and Technology Agency of Japan. Background information was collected on the present status of scientific research facilities in US, European and Asian countries on one hand, and on the expectations and prospects of Japanese scientists on the other hand. Based on the analysis of these data, some measures necessary to expand the international cooperation were proposed. It was emphasized that international joint research on a reciprocal basis would be effective in order to strengthen the technological basis of peaceful uses of nuclear energy. Problems to be solved for the new development were also discussed.

The β-ray spectra of individual fission products were calculated by using the β-decay data assuming every β-decay to be allowed transition. For the nuclides without measured decay data the β-feeding function was evaluated with the gross theory of β-decay and the β-ray spectrum was calculated from the function. The measured decay data were also supplemented with the data calculated by the gross theory for the excitation energy range above the highest measured excitation energy level. The β-ray spectra from aggregate fission products after a burst fission were calculated by using the β-ray spectrum and the atom number of each fission product nuclide and they were compared with the ones measured for thermal neutron induced fission of 235U, 239Pu and 241Pu at Oak Ridge National Laboratory. The spectrum calculations showed excellent agreement with the measured data at shorter cooling times than 10s when many short-lived nuclides without measured decay data contributed considerably to the spectrum.

A 78-year-old woman presented with fever, severe abdominal pain, and distension. She had been institutionalized for depression and senile dementia. Laboratory examinations disclosed a leucocytosis (WBC: 12,500/microL) and elevated levels of serum C-reactive protein (2.8 mEq/L). Diagnosis of acute cecal volvulus was made from a "coffee bean sign" on an abdominal computed tomography and a "beak sign" on a gastrographin enema. An emergent laparotomy confirmed the diagnosis and an ileo-colectomy with primary anastomosis was carried out. The patient recovered after intensive respiratory care and fluid therapy, and then returned to her former institution. A review of Japanese literature disclosed that: (1) a marked increase of aged patients with mental disability presenting with cecal volvulus, (2) adoption of ileo-colectomy as the standard surgical procedure, and (3) improved survival of the patients, were observed in the last decade.

The decay of 11.6 min 152 Nd to levels of odd-odd 152 Pm has been studied with HpGe, Ge(Li) detectors, LEPS, and a plastic scintillation detector by γ-ray singles, time dependent γ-ray singles, γ-γ coincidence and β-γ delayed coincidence measurements. Sources were prepared by a rapid chemical separation method from the fission products of 235 U. Ten γ-rays were observed and five of them are newly observed (19.5, 25.0, 44.4, 545.6 and 570.7 keV). Half-lives of the 16.1 and 28.5 keV transitions were measured to be 2.1±1.0 ns and ≤1.0 ns, respectively. A decay scheme of 152 Nd involving 2 new levels at 25.0 and 570.7 keV in 152 Pm and spin-parities are proposed. The Nilsson configurations of excited states in 152 Pm are discussed.

We have developed a technique of transurethral radiotherapy for prostatic cancer using a remote after-loading system. The radioactive source is a cobalt-60 pellet with 3.7-Ci activity. Four patients with adenocarcinoma of the prostate were treated. In all patients, the local tumor response was rapid and satisfactory as judged by physical examination as well as ultrasonography. Serious complications were not seen. A new technique and preliminary clinical results are reported.

The effects of load and hydrostatic pressure on the tribological characteristics of Si3N4 ceramic sliding on itself were investigated at 120° in water under the hydrostatic pressures of 0.2 and 10MPa. The friction coefficients and specific wear rates at 0.2MPa were larger than those at 10MPa. Both values increased with increasing the loads and saturated at about 60N under 0.2 and 10MPa, resulting in the appearance of the microfracture and production of H2 in addition to NH3. The mechanisms of the hydrothermal oxidation and microfracture of the Si3N4 ceramic are discussed.

The reactor-neutron cross section of the reaction 137Cs(n,γ)138Cs has been measured by means of a radiochemical method. First, the thermal neutron cross section, including a contribution of epithermal neutrons, was determined and found to be twice as large as that of the previous work by D.C. Stupegia. Second, a modified Cd-ratio experiment was carried out, using a movable cadimium shield in a reactor. The thermal neutron cross section (for 2200 m·s−1 neutrons) was 0.25±0.02 band the resonance integral 0.36±0.07 b. In the analysis of the experimental results, a possibility of the production of the 138Cs isomer (T 1/2=2.9 min) was disregarded. The model calculation for the isomeric yield ratio in s-wave neutron capture of 137Cs showed that the cross-section values obtained have a probable error of +1.2% or +3.9%.

The half-lives of short-lived nuclei produced by 14 MeV or thermal neutron bombardments were measured with Ge detectors in the spectrum multi-scaling mode. The corrections for the pile-up loss and the dead time were performed by applying both source and pulser methods. Half-lives of short-lived nuclei, 51Ti, 60mCo, 89mZr, 91gMo, 91mMo, 97mNb, 104mRh, 108Ag and 109mPd, were determined experimentally within 0.1 % accuracy.

A recommendation regarding the FP decay power was issued from the Research Committee on Standardization of the Decay Heat Power in Nuclear Reactors of Atomic Energy Society of Japan (AESJ). The recommendation is primarily based on the results of summation calculations, obtained through using the JNDC FP Nuclear Data Library, Version 2. It consists of decay power values, their estimated accuracy, and their β- and γ-ray components for five fissionable nuclides; U-235, -238, Pu-239, -240 and -241. A set of 33-term exponential polynomials given therein help the users in calculating the decay-power curve for any irradiation history and cooling time. The time evolution for the γ-ray component energy spectra is also given.

Gastrointestinal stromal tumor (GIST) of the stomach was treated by endoscopic enucleation in five patients. They were three men and two woman, aged 36-56 years. Tumors located in the cardia were completely enucleated endoscopically without any serious complication. The largest diameter of removed tumors ranged from 1.2 to 2.5 cm. Histopathological diagnosis was GIST with low risk of malignancy (mitotic index < 5/50 high power field) in all cases. The patients were disease-free for 10.5-42.2 mo after endoscopic enucleation.

A method was proposed to measure β+-activities of radionuclides emitting almost no γ-rays by detecting 511 keV annihilation γ-rays with a Ge detector. The β+-sources with maximum energies up to about 3.4 MeV can be regarded as 511 keV point γ-sources, if the sources are set between two 10 mm thick acrylic plates. The effect of diffused annihilation positions of β+-particles in the absorber on detection efficiencies was observed to be negligible with an accuracy of 1.0%.

The PIXE technique has been successfully applied to investigate the environmental problems caused by the studded tire of automobiles. The dust samples were collected on stacked filters in Sapporo and some other cities in Japan and Europe. PIXE measurements were performed using a 2 MeV proton beam. The results were compared with those of different cities. The main components of dust particulates were Al, Si, Ca, Fe and so on. The vertical distribution of dust concentration in the city of Sapporo was determined by PIXE in April and June. The concentration in April decreases exponentially with height from the ground. The effect of dust particulates due to studded tires is observed up to an altitude 60 m. On the other hand in June, the concentration on the ground is one-tenth of that in April, and it is almost unchanged with the distance in the vertical direction. The concentration of Ca in the dust particulates in the area where the studded tires are used increases by a factor of 2 to 4 in comparison with that in the ordinary soil.

The decay properties of 143 La and 147 Pr were investigated with Ge(Li), NaI(Tl) and plastic detectors in singles and coincidence modes with the help of a rapid paper electrophoresis. Twenty-three new γ-rays for 143 La and 9 new transitions for 147 Pr were observed and fairly precise decay schemes for 143 La including 5 new levels and for 147 Pr including 4 new levels were proposed. The half-lives of 143 La and 147 Pr are 14.14 ± 0.16 and 13.3 ± 0.4 min, and observed Q β values for 143 La and 147 Pr are 3.28 ± 0.10 and 2.77 ± 0.10 MeV, respectively.

An isotope separator was constructed and operated with on-line connection to the INS FM cyclotron. The gas-discharge type ion source was used in the earlier stage. Later the ion source was improved to the hollow-cathode type in order to achieve high temperature and high efficiency. The mean radius and the deflection angle of the separator are 60 cm and 45°, respectively. Mass-separated ions are transported through concrete walls to a tape collector, where radioactivities are measured. As a test experiment, natural copper foils were bombarded with the 52 MeV proton beam, and the reaction products of 63 Zn, 62 Zn, 61 Zn and 60 Zn were separated. The delay time between production and measurement was shortened to 1 min for the Zn isotopes evaporated from the 10 μm Cu foil. Yield ratios of 61 Zn to 63 Zn were measured for proton energies of 30–47 MeV.

The cross sections for the reactions 90Zr (n, n′) 90mZr, 91Zr (n, n′)2n) 90mZr, 207Pb (n, n′) 207mPb and 208Pb (n, n′)2n) 207mPb for neutron energy of 14.8 MeV have been measured by means of the activation method. The cross sections were determined with reference to the known 27A1 (n, α) 24Na reaction cross section. Isotropically enriched isotopes 90Zr, 91Zr, 207Pb and 208Pb were used as target materials. The irradiations and the activity measurements were repeated 100 times using a fast pneumatic transport system. The following cross sections were obtained: 410±40 mb for 90Zr (n, n′) 90mZr, 775±65mb for 91Zr (n, 2n) 90mZr 160±23 mb for 207Pb(n, n′) 207mPb, 1,220±100 mb for 208Pb(n, 2n) 207mPb. From the results of the present work, the effective formation cross sections of 90mZr and 207mPb for natural Zr and Pb have also been estimated as 475±40mb and 900±80mb, respectively