Helmut Paul (born 4 November 1929 in Vienna; died 21 December 2015 in Linz) was an Austrian nuclear and atomic physicist.

The father was employed in the accounting and financial sector of the Siemens company,[1] the mother worked first in the household and later as an interpreter in the American Embassy in Vienna.

Paul spent the year 1950/51 with a fellowship from the US State Department at the Graduate School of Purdue University in Lafayette, USA.

This employment was of great significance for Paul privately as well: He met the secretary of Professor Karlik, Maria Elisabeth Mathis (1931 - 2008), and fell in love with her.

At CERN, the first particle accelerator, the synchrocyclotron, had just started operation, and Paul got the chance to work on the first experiment that was carried out with this machine.

[2] Paul was employed at the Seibersdorf center from October 1960 to March 1971, interrupted by a fourth stay in the USA, this time at the Brookhaven National Laboratory on Long Island (1965/66).

[6] An essential part of his work was devoted to the measurement of the electron-neutrino angular correlation in neutron decay, a difficult project that went on for years and was finally concluded when Paul was no longer at Seibersdorf.

[7][8] In Brookhaven, Paul attempted to find a possible parity admixture in an excited state of a radioactive hafnium isotope, which would manifest itself by a small circular polarization of the emitted gamma radiation.

[14] Later, Paul's interests turned toward the stopping power of matter for charged particles, a subject on which D. Semrad, P. Bauer, R. Golser and other coworkers had already worked intensively for some time.

[22] Even after his retirement from active university duty in 1996, Paul received invitations to specialized conferences abroad, notably to the USA (last time 2012), but also to Brazil (2011).

In 1990, Paul began to establish a collection of all published Stopping Power Data for light Ions, with many graphical displays, and to install it in the Internet.