Chronology of Milestone Events in Particle Physics - MEITNER 1930
Chronology of Milestone Events in Particle Physics


Meitner, L.; Orthmann, W.;
Über eine absolute Bestimmung der Energie der primären -Strahlen von Radium E / Absolute Determination of Energy of Primary Rays from Radium E
Z. Phys. 60 (1930) 143;

Es wird durch eine Wärmemessung die Energie der primären -Strahlen von Radium E-Präparaten festgestellt, deren Radiumäquivalent, also die pro Sekunde zerfallende Anzahl von Atomen, durch eine besondere Untersuchung ermittelt wird, um die von einem einzelnen Kernelektron mitgeführte Energie zu erhalten. Außerdem wird gezeigt, daß Radium E innerhalb eines weit umfassenden Wellenlängenbereiches kein kontinuierliches -Strahlenspektrum besitzt.
Abstract The method employed was a calorimetric one, and the mean value of the energy of a primary -particle was determined. The number of radium E atoms disintegrating per sec was arrived at by preparing standard preparations, calibrated in radium equivalents. The most probable value as obtained is 337,000 volts 6%, which agrees well with the value 344,000 volts 10% obtained by Ellis and Wooster. The actual velocities of the -particles vary from about one million down to 200,000 volts, and a continuous magnetic spectrum is obtained. This distribution of velocity and energy exists when the -particles leave the atomic nuclei. A special experiment showed that RaE does not emit a continuous -ray spectrum, which might compensate for the inhomogeneous character of the disintegration energy given out in the form of -radiation. From the experiments it can be deduced that the number of atoms disintegrating in a second in a gramme of radium is 3.68 x 1010, with a maximum error of 5%. (Science Abstracts. 1930, 2580. H. N. A.).

Related references
See also
C. D. Ellis, Proc. Roy. Soc. A101 (1922) 1;
L. Meitner, Z. Phys. 11 (1922) 35;
W. Gurney and E. U. Condon, Nature 122 (1928) 438;
O. Erbacher and K. Philipp, Z. Phys. 51 (1928) 309;
B. Heiman and W. Marckwald, Phys.Zeitschr. 14 (1913) 303;
H. J. Braddick and H. M. Cave, Proc. Roy. Soc. A121 (1928) 367;
D. V. Skobelzyn, Z. Phys. 58 (1929) 595;
G. Gamow, Z. Phys. 51 (1928) 204;
Analyse data from
C. D. Ellis and W. A. Wooster, Proc. Roy. Soc. A117 (1927) 109;

  210Bi 210Po e X p

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Firm establishment that the spectrum is continuous.
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