A 25 GeV Electron facility for Europe.

Report on the ELFE @ HERA project.

The Concept Design Report (CDR) has been completed. A PDF version (411 kB) of this report is available at the NIKHEF site.


A short description of the ELFE proposal is available. A full report has been published in october 1992:


An Electron Facility for Europe, edited by J. Arvieux and E. De Sanctis

After termination of the present physics program with HERA at DESY, Hamburg, possible use of the ring as a stretcher ring for ELFE could be considered. In February 1996 an international study group has been formed by Bernard Frois (Saclay) to study the modification of the HERA electron ring into a 25 GeV stretcher ring for electrons.

Details of the study group:

The goal of the study group was :

The main efforts


Solutions have been found for these problems, although the control of beam instabilities will probably not be easy. The achievable performances of the extracted beam have been calculated assuming that the effects of machine imperfections could be corrected.

The performance that can be expected:

Energy rangeGeV 15 - 25
Energy spread(promille) 1.2 (15 GeV) - 2.2 ( 25 GeV)
Maximum currentmicroAmp 30
Macroscopic duty factor percent 88
Bunch spacingnanoseconds. 2.3 (433 MHz)
Min. horizontal emittance mm * microrad 4 (15 GeV) - 12 (25 GeV)

Therefore, we conclude that HERA can be used in association with TESLA to produce a high duty factor electron beam for fixed nuclear target experiments.

ELFE@DESY appears to be feasible

The study group has terminated its activities.

The next activities will be:

Updated on *

We welcome your remarks and suggestions.