Department of Particle Physics and Astrophysics

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Giora Mikenberg

Professor, Center Head
Location:Edna and K.B. Weissman Building of Physical Sciences, Room 330

Current Research Interests

Although the universe in which we live looks very complex, with a large variety of different molecules and four forces (Nuclear, Electro-magnetic, Weak, which is responsible for radioactivity, and Gravity),  it is assumed that at the beginning of the universe, there was a single,  unified force. With the decrease of the collision energies during the expansion of the universe, this force split into the four forces we know now. 

Using the largest particle accelerator in the world, the LEP machine with its 27Km circumference and four experiments (one of the four, OPAL has a strong participation of the Weizmann Experimental High Energy Group), where collision energies of 200GeV are obtained, one has been able to show that the electromagnetic and the weak forces are a one single force. Furthermore, one has shown in these experiments that the strength of the electroweak and of the nuclear force change with the collision  energy. By extrapolating the change in strength, one finds out that they  do not meet at a single energy, unless a new family of particles exists  with masses close to the collision energies that are available in the LEP machine or in the future LHC accelerator that will start operations in 2005. Two very important unknowns remain in this picture: for the unification of the electromagnetic and weak force to take place a new  type of particle has to exist that provides the mass to all other point-like  particles in nature, the Higgs Boson; while to be able to achieve the unification with the nuclear force, a new family of particles that provide a symmetry between particles that  make ordinary matter and those that transport forces, called Super-Symmetric particles, should be found. With the support of the Israeli  Science Foundation Center for the Search of the Higgs Boson at LEP and  LHC and the Benoziyo Center for High Energy Physics, the Weizmann group working at LEP has been searching for the Higgs boson (see report by E. Gross) and for Super-Symmetric particles (see report by E. Duchovni).

In parallel to this activity at the presently running accelerator (LEP), I have also been involved in the search for the lowest  mass states of the Super-Symmetric particles (Charginos and  Neutralinos).  The group is also involved in the development and construction of particle detectors and their corresponding trigger and readout electronics for a system that will provide the trigger for the searches of Higgs and  Super-Symmetric particles in one of the two experiments that will run at  the future accelerator, LHC. The detectors are based in a technology  developed at the Weizmann Institute, that has been used in the LEP accelerator called Thin-Gap Chambers (TGC), that has been modified for  large area detectors with the best time resolution ever achieved in wire chamber particle detectors.

This activity takes place with the participation of D. Lellouch and L. Levinson. A full description of the results achieved in the LEP activity can be found at:, while news about the LHC activity can be found at