Aleksander Rajchman was born in Warsaw on 13 November 1890. He studied in Paris obtaining "licencié és sciences" in 1910. In 1919 he obtained a position at the University of Warsaw, first as a junior assistant, and, after obtaining his PhD in 1921, as a senior assistant. In 1922 Rajchman became a professor at the Free University in Warsaw (Wolna Wszechnica) and in 1925 he made a habilitation at the University of Warsaw and lectured at this University as a Privat Docent until 1939. In the late thirties he lectured in College de France at the seminar of J. Hadamard.
Aleksander Rajchman started to work in trigonometric series under the influence of Hugo Steinhaus, he worked also in real functions, probability and mathematical statistics. The list of his publications counts 40 positions.
Rajchman had a strong influence on S. Saks and A. Zygmund by introducing them into research in the theory of real functions and of trigonometric series. Jointly with Antoni Zygmund he wrote three papers on trigonometric series.
Aleksander Rajchman was arrested by Gestapo in April 1940 and perished in the concentration camp in Sachsenhausen, probably in July or August 1940.
(The above informations are taken mostly from an article of Antoni Zygmund published in Wiadomości Matematyczne 27 (1987), 219-231.)