Construction Plans for the LENS Proton Linac

The Low Energy Neutron Source (LENS) at Indiana University will provide moderated neutrons in the meV energy range for materials and neutron physics research as well as MeV energy range neutrons for creating a high flux neutron test environment. Neutrons will be generated by colliding 13 MeV protons with a Be target. Since December 2004, using an existing AccSys PL-7 RFQ and DTL, we have been able to deliver a 0.5% duty factor, 10 mA, 7 MeV beam to a Be target mounted next to a 3.6K methane moderator. In 2007, an additional 7 MeV to 13 MeV DTL section will be added and klystrons will be used to power the RFQ and DTL sections. This will improve the output to about 3% duty factor with 20 mA at 13 MeV. A new 75 keV, 150 mA proton injector and 100 mA, high duty factor RFQ is being constructed to replace the original 3 MeV RFQ at a later date. The peak beam current available from the new injector and RFQ will increase to 50 mA with a duty factor of at least 5% or up to 100 mA with lower duty factor. In addition, a conceptual plan has been developed for a 13 MeV to 22 MeV DTL which will boost the maximum instantaneous flux available from the neutron source up to about 10 n/s/cm. LENS UPGRADE PATH A description of the LENS accelerator project may be found elsewhere [1-4]. The two primary uses of the accelerator will be to generate a low energy flux of neutrons for materials and neutron scientists [5] and to provide a higher energy neutron flux for a radiation effects program (NREP) [6]. The NREP program a part of the accelerator construction has been supported by the Department of Defense through NAVSEA Crane. Two separate targets will be installed for these two primary users, a high energy, high instantaneous flux target for the NREP users and a target surrounded by a custom moderator optimized for materials physics (particularly large scale structures). LENS is now in operation [1] but is limited to a low neutron flux due to a low average proton current and energy of only 7 MeV. An upgrade path to increase the neutron flux by more than two orders of magnitude is outlined in Table 1. During the next phase of operation the PL-7 will be upgraded to 13 MeV and powered by three klystrons. Further improvements will be realized by increasing the duty factor of the klystrons by adding a more powerful modulator supply and by installing a new 100 mA, 3 MeV RFQ which is presently under construction. Details of these upgrade components are described below. Figure 1: Layout of the Phase 4 LENS project with a 13 MeV, 100 mA proton accelerator shown installed. The 3 MeV RFQ is 3 meters long. The 13 MeV Phase 2 version will require 3 klystrons and a conceptual 22 MeV Linac would require 5 klystrons. ___________________________________________ *Work supported by the National Science Foundation under Grant Nos. DMR-0220560 and DMR-0320627, by the Indiana 21st Century Science and Technology Fund, by the Department of Defense and by the Indiana University. vderench@indiana.edu MOP050 Proceedings of LINAC 2006, Knoxville, Tennessee USA 156 Accelerators and Facilities Ion Linacs