The HL-LHC luminosity goals pose various challenges that come from the increased radiation environment. Many magnets and equipment in the vicinity of the beam collision or beam service points will suffer from increased radiation levels, stemming part from the debris and part from the primary beam: the energy deposition must be carefully evaluated for proper functionality of the magnets, preventing induced quench. In addition, the cryogenic system capacity has to suit the total power absorbed by the cold masses, which in the experimental insertions scales proportionally to the peak luminosity as well.
Moreover, dedicated protection devices (like the TAS and the TAN) and local shielding must sustain the induced thermomechanical stress. On the other hand, the target integrated luminosity represents a quite demanding requirement in terms of lifetime of several components (superconducting cables, insulators, instrumentation) as well as electronics reliability versus the risk of single event effects and long-term damage, related respectively to the particle fluence and dose to which materials and equipment are exposed.
In order to face such challenges, contributing to the machine design optimization and preventing critical showstoppers, radiation-matter interaction simulations, as accurate as possible, are essential, and imply the detailed and reliable modelling of the whole areas of interest as well as the proper characterization of the relevant source terms, including beam losses in addition to beam-beam collisions. The energy deposition studies feed into almost all work packages and have to accompany and orient the layout and optics finalization.
In particular, together with the responsibility for the maintenance of the respective machine model, a list of upcoming tasks follows:
- possible mitigation measures have to be evaluated in order to suitably address the weak point represented by the tungsten shielding interruption in the triplet interconnections;
- the effectiveness of the matching section protection scheme has to be validated;
- the leakage in the dispersion suppressor has to be quantified;
- the impact of the particle shower from the incoming beam, on the machine elements and up to the detector, has to be taken into account;
- the scenario of an LHCb upgrade beyond nominal ATLAS and CMS luminosity has to be precisely investigated;
- the radiation environment in the tunnel and in the service areas, has to be assessed.
For what concerns the appropriate radiation monitoring, qualification tests related to radiation damage for both materials and electronics, as well as the common development of radiation tolerant electronic systems, WP10 keeps a direct link to associated activities in the R2E project ensuring:
- an appropriate long-term monitoring of the radiation levels in the LHC and its injector chain;
- the availability of dedicated radiation test facilities including both facilities at CERN (CHARM and CC60) as well as dedicated contracts and follow-up with external test facilities (PSI, Fraunhofer, etc.);
- adequate radiation testing and direct support for respective design of test circuits;
- an appropriate selection, qualification and purchase of electronic components, aiming for and promoting common solutions across equipment groups whenever possible;
- the design, upgrade and qualification of electronic equipment installed in the accelerator tunnel or its vicinity, with particular focus on: power converters (60A and 120A), quench protection systems, cryogenics control and powering, beam instrumentation as well as vacuum related equipment;
- linked to the above, that common communication link solutions are developed and deployed;
- the design and implementation of dedicated radiation shielding measures;
- the study of optional relocation measures (around IP4 and IP6).