The ILL welcomes several categories of Long-Term Visitor to the ILL. Most visitors are involved in the scientific and technical life of the institute in the following ways:

• Scientists, engineers and technicians from neutron research laboratories world-wide, but especially from Associate and Scientific Member countries, collaborating on experimental facilities and technical developments, and/or working on experiments that take many months to complete.

• Scientists on sabbatical leave from universities who spend an extended period in the active research environment of the ILL to carry out a prepared scientific programme free from their regular teaching or administrative duties.

• Members of Colllaborative Research Groups (CRG) and Externally Funded Initiatives (EFI), building and/or operating CRG or EFI facilities at the ILL.

• PhD students from partner universities for whom a major part of their research is based on experimental results obtained at ILL.

• Post-doctoral research scientists acting on behalf of ILL user groups based in partner universities.

• Engineers and computer experts working on specialised projects for the development of new techniques or infrastructure.

The ILL recognises that these scientific collaborations globally benefit the ILL by contributing to the scientific life and reputation of the institute and by helping to establish mutually beneficial relationships with other national or international research organisations.