Ishiwari, Ryutaro

Shiomi, Naoko

Shirai, Shigeko

Kyoto University Research Information Repository

Title Stopping Powers of Be, Al, Ti, V, Fe, Co, Ni, Cu, Mo, Rh, Ag,Ta, and Au for 28.8 MeV Alpha ParticlesAuthor(s)Ishiwari, Ryutaro; Shiomi, Naoko; Shirai, ShigekoCitationBulletin of the Institute for Chemical Research, KyotoUniversity (1977), 55(1): 60-67Issue Date1977-03-31URL http://hdl.handle.net/2433/76712RightType Departmental Bulletin PaperTextversionpublisherKyoto University Bull. Inst. Chem. Res., Kyoto Univ., Vol. 55, No. 1, 1977   Stopping Powers of Be, Al, Ti, V, Fe, Co, Ni, Cu, Mo,     Rh, Ag, Ta, and Au for 28.8  MeV Alpha Particles            Ryutaro ISHIWARI, Naoko SHIOMI, and Shigeko SHIRAI*                             Received January 31, 1977    Stopping powers of Be, Al, Ti, V, Fe, Co, Ni, Cu, Mo, Rh, Ag, Ta, and Au for 28.8 MeV alpha particles have been measured with a silicon detector and associated electronic equipment. It has been confirmed that the stopping power for alpha particles devided by 4 is higher than that for protons of the same velocity. The deviations are from 2.4 to 4 percent.                          I. INTRODUCTION   It was first found experimentally by Andersen et al.1' that one fourth of the stopping power for alpha particles is slightly larger than the stopping power for protons of the same velocity. And this effect was experimentally confirmed by our previous experiment')    Presently, this effect has been explained as the effect of higher Born approxima-tion and called Zl effect,') where Z1 is the atomic number of the particles. These theories of Zi effect agrees fairly well with the experiment of Andersen et al.5'    In a recent letter," we have reported that our recent measurements of stopping powers of various metallic elements for 28.8 MeV alpha particles do not agree with the theories and the differences between the stopping powers for alpha particles and for protons are larger than those predicted by the theories.    Although there remains yet a questions') whether our proton data are too low or the proton data of Andersen et al.'° " are too high, we want to report here the details of our new experiments and the full data on 28.8 MeV alpha particles.                    II. EXPERIMENTAL PROCEDURE    The alpha particles accelerated with the Kyoto University Cyclotron were used for the present experiment. The method to measure the energy loss of alpha par-ticles in sample foils is quite the same as described in detail in the previous papers.l4'15)    Figure 1 shows the experimental setup. The absolute value of the incident alpha particle energy was determined by the analyzing magnet. The effective radius of curveture of the alpha particle paths in the analyzing magnet has been determined in the previous experiment.55) The very same value was used in the present experiment. Therefore, the energy scale of the present measurements is based on the same energy calibration as the previous measurements for protons.15)    The beam scattered at an angle of 15 degrees by a gold scatterer of 180 ,ug/cm2 was used for the measurement. The sample foil was fitted to one of the two windows * O#s : Department of Physics, Faculty of Science, Nara Women's   University, Nara. ( 60 )                    Stopping Powers for 28.8 MeV Alpha Particles  lo› CYCLOTRON                                      Q MAGNET                             4 ANALYZING51                   MAGNET                                     REACTION CHAMBER                              ^PUMP 52        ABSORBER 53 WHEEL. AU FOIL 160 g/cm2µ j~ a-15°           o MOTOR ~~54              'BSORBER5PUMP                                    PRE AMPPRECISION             SILICON( PULSER                     DETECTOR                                 MAIN AMP                .400 CHANNEL            PULSE HEIGHT ANALYZER I BIASED AMP                  Fig. 1 Experimental setup for the energy loss measurement. of the absorber wheel and the wheel was rotated in front of a silicon detector (OR-TEC). Thus, the pulse heights with and without the sample foil were measured simultaneously in one exposure. The double slit system consists of S4 and S57 which have circular apertures of 1.5 mm and 2.0 mm in diameter and are placed 80 mm apart. This device was set between the absorber wheel and the detector to limit the direction of the alpha particles incident on the detector.    The pulses from the detector were amplified with a low noise amplifier and the relevant portion of the pulse height spectrum was expanded by a biased amplifier. The output of the biased amplifier was fed into a 400-channel pulse height analyzer.    The energy calibration of the expanded pulse height spectrum was performed by measuring the alpha particles elastically scattered by an aluminium target of 1.692 mg/cm2 at various angles and was crosschecked by a precision pulser. ( 61 )                            R. ISHIWARI, N.  SHIOMI, and S. SHIRAI    The measurements were made four times for each element and the average val-ues were obtained.    The sample foils used are as follows: Beryllium    Thickness: 2.4301+0.0063 mg/cm2. Stated purity: unknown but presumed to be 99 percent or up. Supplier: Brush Beryllium Co. The very same foil as used in the previous experiment." Aluminium    Thickness: 4.937410.0074 mg/cm2. Stated purity: 99.8 percent. Supplier: Toyo Aluminium Co., Ltd. Titanium    Thickness: 6.154710.0092 mg/cm2. Stated purity: 99.5 percent (0.25 percent Fe). Supplier: A. D. Mackay, Inc. Vanadium    Thickness: 7.6299+0.0114 mg/cm2. Stated purity: 99.9 percent. Supplier: A.D. Mackay, Inc. Iron    Thickness: 6.1285+0.0092 mg/cm2. Stated purity: 99.9 percent. Supplier: Fukuda Metal Foil and Powder MFG Co., Ltd. Cobalt    Thickness: 9.188410.0138 mg/cm2. Stated purity: 99.9 percent. Supplier: A.D. Mackay, Inc. Nickel    Thickness: 6.720510.0101 mg/cm2. Stated purity: 99.9 percent. Supplier: Fukuda Metal Foil and Powder MFG Co., Ltd. Copper    Thickness: 7.417810.0111 mg/cm2. Stated purity: 99.9 percent. Supplier: Fukuda Metal Foil and Powder MFG Co., Ltd. Molybdenum    Thickness: 6.805010.0102 mg/cm2. Stated purity: 99.95 percent. Supplier: A.D. Mackay, Inc. The very same foil as used in the previous experiment.' Rhodium    Thickness: 7.748810.0116 mg/cm2. Stated purity: 99.9 percent. Supplier: A.D. Mackay, Inc. Silver    Thickness: 8.961310.0134 mg/cm2. Stated purity: 99.9 percent. Supplier: Fukuda Metal Foil and Powder MFG Co., Ltd. Tantalum    Thickness: 10.3447+0.0155 mg/cm'. Stated purity: 99.9 percent. Supplier: A.D. Mackay, Inc. The very same foil as used in the previous experiment.' Gold    Thickness: 10.506010.0158 mg/cm'. Stated purity: 99.95 percent. Supplier: Ishifuku Metal Industry Co., Ltd. The very same foil as used in the previous ex-periment." ( 62 )                    Stopping Powers for 28.8 MeV Alpha Particles                             HI. RESULTS    The typical pulse height spectra are shown in Fig. 2. The numerical results of the pulse height measurements for Al, Ag, and Au are shown in Table I as examples.    From the measurement of the elastically scattered alpha particles by the alumin-ium target at different angles, the energy scale of the pulse height spectra was determined as 14.7857±0.0605  keV/channel.                                                               -1000      '— Ni z 0 U-                                                              - 500  300—-                             M •.• p•-         200 —.0 . 100—       y o •-      0..r— ''• `'r°44  0 160 200 220 240 260 260                              CHANNELS                              (a) Ni -             tn                   Ta         0 U    200—• • — 500 •• .~- ••• 100—                  • _                                                                                            •                                                      0              180 200 220 240 260 280                              CHANNELS (b) Ta                         Fig. 2 Typicalpulseheightspectra.    Table II lists the results. In the table, At is the thickness of the foil, dE is the energy loss of alpha particles in the sample foil. The symbol E denotes the average energy defined as         E = Eo-4E12 , ( 63 )             R.Isxtwnxi, N. SxioMi, and S. Huzai  Table I. Examples of Numerical Results of Pulse Height Measurements. P.E.       Denotes the Propagation Error and S.E. Denotes the Standerd Error   Element  No Absorber    Absorber Peak    Pulse Height Difference   and Run  Peak(channel)     (chanllel)         (ch狐nel)Al  Run 1   262.267土0.034    203.190 0.047      59.078土0.058   Run 2      262.650土0.036      203.572土0.053         59.078=」0.064   Run 3    262.823土0.043    203.845土0.063      58.978土0,076   Run 4   262,221±0.037    203.131士0.054      59.090」=0.066   Average   262.490土0.019(P.E.)               59.056土0.033(P.E,)             ±0.147(S.E.)                    土0.026(S.E.)Ag  Run 1    263.723土0.042    192,280土0.087       71.443土0,096   Run 2      263.673土0.043      192.149=ヒ0.090          71.524±0.100   Run 3   263.973 0.040    192.567 0.087      71.406 0.096   Ru皿4      263.429士0.040      1si.s4i±0.087         71.588±0.095   Average   263.699=』0.021(P.E.)                71.490土0.049(P.E。)             土0.ll2(S.E.)                   ±0.051(S.E.)Au  Run l    262.247土0,041    197.408土0.112       64.840±0.119   Ru皿2    262,419土0.042    197.520=』0.111      64.899土0.119   Run 3    263.279±0.041    198.734±0.115      64.545土0.122   Run 4     263。056=』0,039     198.185±0.114        64.871土0. izo   Average   262.750土0.020(P.E.)               64.789土0.060(P.E。)             =』0.248(S.E.)                    =ヒ0・079(S・E・)      Table II. Results. The Incident energy is 28.75520.0177 MeV.・1・m…(mll。m・)(dEkeV) ﾉ ﾉ' (・。V認 盤 一・) Be       2.4301     477.4     28.5165    7.1783       196.45       」=0.0063       ±2.1      =』0.0177                   土1.00 Al        4.9374      873.2      28.3186     7.1285        176.85       士0.0074       =h3.6      土0.0178                  ={=0・85 Ti      6.1547    943.8    28.2833    7.1196      153.35      ±0.0092      ±3.9     」=0.0178                  ±0.74 V7.62991136.528.18707.0954148.95       =LO.0114       =」4.7      =」=0.0178                   =LOg72 Fe        6.1285      902.4      28.3040      7.1248        147.25       =LO.0092       =』=3.7      」=0.0178                   =f二〇。71 Co        9.1884     1333.6      28.0884     7.0705        145.14       =ヒ0.0138       ±5,5      土0.0179                  土0.70 Ni     6.7205    993.8    28.2583   7.1133     147.88       =』0.0101       =』4.1      土0.0178                   =LO.72 Cu      7.4178    1033.7     28.2384    7.1083      139.35       ±0。Ol11      =』4.3      =』0.0178                   土0.67 Mo    6.8050   833.9   28.3383   7.1334    122.54       ±0.OlO2       =ヒ3.5      士0.0177                   ±0.60 Rh     7.7488    914.0    28.2983   7.1234     117.95       ±0.Ol16       =ヒ3.8      土0.0178                   =」0,57 Ag     8.9613    1057.0    28.2267    7.1054      117.95       土0.0134       土4.4      」=0,0178                   =】=0.57 Ta     10.3447    963.1    28.2737    7.1772      93.10       =ヒ0.0155       土4.4      =』0.0178                   ±0・49 Au       10.5060      957.9      28.2763      7.1178         91.18       =」=0.0158       ±4.1      士0.Ol78                   」=0.45                    (64)                    Stopping Powers for 28.8 MeV Alpha Particles where  Eo is the incident alpha particle energy. The symbol E' denotes the energy of protons which have the same velocity as alpha particles of energy E. The ratio dE/dt corresponds in a good approximation to the stopping power, -dE/dt, at the average energy E.    Since in the present experiment only alpha particles which passed through the double slit system S4 and S5 were detected by the silicon detector, the actual path length of alpha particles in the foil was assumed to be equal to the foil thickness and no correction was made for the multiple scattering. The systematic error caused by this approximation is at most 0.05 percent.    Further, since in the present experimental setup the alpha particle beam does not scan all over the sample foil, an additional error of 0.2 percent has been added to the stopping power values. This additional error stands for the possible nonuniformi-ty of the sample foil.    The effect of the geometry in the energy loss measurement has been investigated earlier.'s) It has been confirmed that the goodness of the geometry does not affect the energy loss measurement for the degree of goodness of the geometry in the present experiment.                            IV. DISCUSSION 1. Comparison of Present Results with Previous Results     In Table III, the comparison of the present results with the previous results') for common elements are shown.    Table III. Comparison with the Previous Alpha Data. All values have been devided              by 4 and reduced to 7.0 Mev. ElementPresent DataPrevious Data*Difference (keV/mg cm-2) (keV/mg cm-2)(%)     Be50.32±0.2749.25±0.49+2.13±1.11      Al45. 00 ± 0.2245.01±0.44-0.02±1.09                                                Cu35.36±0.1735.03±0.33+0.93±1.05     Mo31.20±0.1531.43±0.30-0.74±1.09      Ta23.65±0.1223.69±0.23-0.17±1.10      Au23.17±0.1122.85±0. 22+1.38±1.08                                                                         * ref. 2    All values have been devided by 4 and reduced to the proton energy of 7.0 MeV. The reduction of the stopping power value to 7.0 MeV was made by multipling (ln v2/v2),„/(ln v2/v2).    Only for Be the difference are barely significant. But for other elements the differences are not significant statistically. Taking account of the errors of the previous data (- l percent), the general agreement between the old and new data is satisfactory. ( 65 )                              R.  ISHIWARI, N. SHIOMI and S. SHIRAI 2. Comparison of Present Data with Our Proton Data     In Table IV, the comparison of the present data with our own proton data14" are shown. The differences amount to from 2.5 to 4 present.     Table IV. Comparison with our Proton Data. Present results have been devided by               4 and reduced to 7.0 MeV.     Element(dE/dx)**(dE/dx)a,X 1/4 Difference (keV/mg cm 2)(keV/mg m-2)(%)      Al43.62±0.1545.00±0.223.16±0.61      Ti37.65±0.1738.97±0.193.51±0.66      Fe36.18±0.1637.45±0.183.51±0.66      Ni36.16±0.1937.55±0.183.84±0.72      Cu34.50±0.1235.36±0.172.49±0.60      Mo29.94±0.1431.20±0.154.21±0.70     Ag28.98±0.1129.92±0.143.24±0.61      Ta23.08±0.1123.65±0.122.47±0.69     Au22.26±0.0923.17±0.114.09±0.64    * ref. 14, 15.    The comparisons with our proton data as well as with the Zi theory') have already been reported." However, in the recent study') of the stopping powers of various elements for 6.75 MeV protons, it has been revealed that our previous data for protons') might be too low by some 1 percent. Consequently, the true differ-ences might be some 1 percent samller than as shown in Table IV. Therefore, we want to withhold the discussion about the comparison of the present data with the the proton data until the correct stopping power data for protons are established. 3. Comparison of Present Data with Andersen's Data    For reference, in Table V the present results are compared with the data of Andersen et al.10-12>     Table V. Comparison with Andersen's Data. The Present results have been devided              by 4 and reduced to 7.0 MeV.     Element(4E/40,x 1/4Andersen*Difference (keV/mg cm-2)(keV/mg cm-2)(%)     Be50.32±0.2750.34±0.15-0.04±0.62    Al45.00±0.2244.81±0.13+0.42±0.58     Ti38.97±0.1938.92±0.12+0.13±0.56     V37.73±0.1837.80±0.11-0.19±0.56     Fe37.45±0.1837.28±0.11+0.45±0.56      Co36.64±0.1836.06±0.11+1.58±0.57      Ni37.55±0.1837.29±0.11+0.69±0.56      Cu35.36±0.1735.12±0.11+0.68±0.57     Ag29.92±0.1429.48±0.09+1.47±0.57     Ta23.65±0.1223.66±0.07-0.04±0.59      Au23.17±0.1122.67±0.07+2.16±0.56    * ref. 10,-13. ( 66 )                   Stopping Powers for 28.8 MeV Alpha Particles    For most elements, the present results agree well with the data of Andersen et al. For  Co, Ag, and Au, the differences are statistically significant.    Although not yet surely established, the data of Andersen et al. are considered to be slightly too high!) Therefore, Table V should be Linterpreted as showing slight differences between stopping powers for alpha particles and protons at the proton velocity of 7 MeV. Further discussion will be deferred until the correct stopping power data for protons are undoubtely established.                       ACKNOWLEDGMENTS   The authors would like to thank Professor T. Yanabu for his encouragement and support throughout the work. Thanks are also due to Mr. K. Fujita and the members of the cyclotron crew of Kyoto University for their kind cooperation.                           REFERENCES (1) H. H. Andersen, H. Simonsen, and H. Sqlprensen, Nuclear Phys., Al25, 171 (1969).  (2) R. Ishiwari, N. Shiomi, S. Shirai, T. Ohata, and Y. Uemura, Bull. Inst. Chem. Res., Kyoto Univ.,     49, 403 (1971).  (3) J. C. Ashley, R. H. Ritchie, and W. Brandt, Phys. Rev., B5, 2393 (1972).  (4) J. D. Jackson and R. L. McCarthy, Phys. Rev., B6, 4131 (1972).  (5) J. C. Ashley, R. H. Ritchie, and W. Brandt, Phys. Rev., A8, 2402 (1973).  (6) J. C. Ashley, Phys. Rev., B9, 334 (1974).  (7) R. Ishiwari, N. Shiomi, and S. Shirai, Phys. Lett., MA, 53 (1975).  (8) Our new experiment. To be soon published elsewhere.  (9) H. H. Andersen, Phys. lett., 56A, 443 (1976). (10) H. H. Andersen, C. C. Hanke, H. Skensen, and P. Vajda, Phys. Rev., 153, 338 (1967). (11) H. H. Andersen, C. C. Hanke, H. Simonsen, H. SOrensen, and P. Vajda, Phys. Rev., 175, 389     (1968). (12) H. H. Andersen, H. Simonsen, H. Sq rensen, and P. Vajda, Phys. Rev., 186, 372 (1969). (13) H. Sorensen and H. H. Andersen, Phys. Rev., B8, 1854 (1973). (14) R. Ishiwari, N. Shiomi, S. Shirai, T. Ohata, and Y. Uemura, Bull. Inst. Chem. Res., Kyoto Univ.,     49, 390 (1971). (15) R. Ishiwari, N. Shiomi, S. Shirai, and Y. Uemura, Bull. Inst. Chem. Res., Kyoto Univ., 52, 19     (1974). (16) R. Ishiwari, N. Shiomi, T. Katayama-Kinoshita, and F. Sawada-Yasue, J. Phys. Soc. Japan,     39, 557 (1975). ( 67 )

Stopping Powers of Be, Al, Ti, V, Fe, Co, Ni, Cu, Mo, Rh, Ag, Ta, and Au for 28.8 MeV Alpha Particles

http://repository.kulib.kyoto-u.ac.jp/dspace/bitstream/2433/76712/1/chd055_1_060.pdf

Stopping Powers of Be, Al, Ti, V, Fe, Co, Ni, Cu, Mo, Rh, Ag, Ta, and Au for 28.8 MeV Alpha Particles

Abstract

Similar works

Full text

Available Versions

Kyoto University Research Information Repository