TY - JOUR

T1 - New Forensic Insight into Carl Auer von Welsbach's 1910 Observation of Induced Radioactivity

T2 - Theoretical, Experimental and Historical Approaches

AU - Steinhauser, Georg

AU - Adunka, Roland

AU - Hainz, Dieter

AU - Löffler, Gerd

AU - Musilek, Andreas

N1 - Funding Information: We thank the heirs of Auer's heritage for supporting this study by providing many objects to the Auer von Welsbach-Museum in Althofen and for providing access of their invaluable objects for our investigations. Further we thank Treibacher Industrie-AG for kindly conducting SEM/EDX analyses on the crucible. G. Steinhauser gratefully acknowledges support by the Austrian Academy of Sciences in the form of the Bader Award for the History of Sciences as well as the Theodor Körner Fonds in the form of the Theodor Körner Award, respectively. Lastly, we thank E. Strub for discussing his ideas with us.

PY - 2016/10/1

Y1 - 2016/10/1

N2 - In 1910, Carl Auer von Welsbach noted that he had made an observation of a radioactive substance inducing radioactivity to an inactive substance. From today's point of view, this could have been the first observation of neutron activation. Herein, we present new insights into our investigation of this ‘mysterious observation’ as Auer von Welsbach termed it. We believe that one of the activated objects was a platinum–iridium crucible. The dominating activation product of the crucible could have been iridium-194. We have discovered several platinum crucibles from Auer's heritage and investigated them by gamma-spectrometry and, one of them, by SEM/EDX. In the EDX investigations, however, no iridium was found in the most promising crucible. Hence this particular crucible was probably not the activated object. In any case, gamma-ray spectrometry revealed very low but detectable amounts of natural radionuclides. This indicated that these crucibles were used by Auer von Welsbach for his radioactive work and that these crucibles were bought prior to World War I. Hence Auer von Welsbach somehow managed to save these crucibles from the noble metal collections during the war. Auer's 1910 publication carried the suffix ‘Part I’, however, Part II was thought to be lost. In our recent work, however, we rediscovered a hand-written manuscript of Part II, in which the peculiar observation is mentioned vaguely. Lastly, we converted Auer's uranium standard into becquerels. Based on this conversion, we estimated that Auer von Welsbach observed an 194Ir activity of the crucible of 500 kBq. It is further estimated that a (thermal) neutron flux density of approximately 8E+4 cm−2s−1 was needed to activate the crucible in a way to meet Auer's description.

AB - In 1910, Carl Auer von Welsbach noted that he had made an observation of a radioactive substance inducing radioactivity to an inactive substance. From today's point of view, this could have been the first observation of neutron activation. Herein, we present new insights into our investigation of this ‘mysterious observation’ as Auer von Welsbach termed it. We believe that one of the activated objects was a platinum–iridium crucible. The dominating activation product of the crucible could have been iridium-194. We have discovered several platinum crucibles from Auer's heritage and investigated them by gamma-spectrometry and, one of them, by SEM/EDX. In the EDX investigations, however, no iridium was found in the most promising crucible. Hence this particular crucible was probably not the activated object. In any case, gamma-ray spectrometry revealed very low but detectable amounts of natural radionuclides. This indicated that these crucibles were used by Auer von Welsbach for his radioactive work and that these crucibles were bought prior to World War I. Hence Auer von Welsbach somehow managed to save these crucibles from the noble metal collections during the war. Auer's 1910 publication carried the suffix ‘Part I’, however, Part II was thought to be lost. In our recent work, however, we rediscovered a hand-written manuscript of Part II, in which the peculiar observation is mentioned vaguely. Lastly, we converted Auer's uranium standard into becquerels. Based on this conversion, we estimated that Auer von Welsbach observed an 194Ir activity of the crucible of 500 kBq. It is further estimated that a (thermal) neutron flux density of approximately 8E+4 cm−2s−1 was needed to activate the crucible in a way to meet Auer's description.

KW - Carl Auer von Welsbach

KW - Discovery of neutron activation

KW - History of Science

KW - Nuclear Forensics

UR - http://www.scopus.com/inward/record.url?scp=85008946395&partnerID=8YFLogxK

U2 - 10.15488/1216

DO - 10.15488/1216

M3 - Article

AN - SCOPUS:85008946395

VL - 41

SP - 297

EP - 318

JO - Interdisciplinary science reviews

JF - Interdisciplinary science reviews

SN - 0308-0188

IS - 4

ER -