ELENA – An Updated Cost and Feasibility Study

To produce dense antiproton beams at very low energies (100 keV), it has been proposed to install a small decelerator ring between the existing AD ring and the experimental area. Phase-space blowup during deceleration is compensated by electron cooling such that the final emittances are comparable to the 5MeV beam presently delivered by the AD. An immediate consequence is a significant increase in the number of trapped antiprotons at the experiments as outlined in the proposal CERN/SPSC-2009-026; SPSC-P-338. This report describes the machine parameters and layout of the proposed ELENA (Extra Low ENergy Antiproton) ring and also gives an approximate estimate of cost and manpower needs. Since the initial estimate, published in 2007 (CERN-AB-2007-079), the ELENA design has evolved considerably. This is due to a new location in the AD hall to accommodate for the possibility of another experimental zone, as suggested by the SPSC, and also due to improvements in the ring optics and layout. The cost estimate that is presented is based on the initial document and has been updated according to the improvements in the design and layout. Where applicable, inflation has also been taken into account. The SPSC has recognized the substantial potential impact of ELENA on the AD experimental program and “strongly supports the ELENA proposal” (minutes of the meeting 29.09.2009) and the RB endorsed the conclusion from the SPSC concerning the strong scientific case for ELENA (minutes of the meeting 02.12.2009).