The quench tests considered here are collimation quench tests, similar to the usual loss maps measurements. The beam is blown up in the horizontal plane, creating losses at the primary collimator in IR7 and consequently on the entire collimation system. The collimators are open to very relaxed settings. The leakage from IR7 leads to energy deposition at the same level as the quench levels of the elements seeing the highest losses.
The comparison with FLUKA simulations was presented at the Collimation Review 2013.
The original presentation is available here:
| E. Skordi et al. | FLUKA Energy deposition simulations for quench tests pdf pptx |
The first step is to generate a full FLUKA geometry of this section of the LHC. One of the critical points is the real position of the BLMs, which can differ from the theoretical position. This studied showed that a few centimetres can mae a difference in the simulated signal.
FLUKA geometry of the warm section of IR7
FLUKA geometry of the DS and arc downstream IR7
The energy deposition studies are divided in several steps. First, SixTrack simulations of the particle trajectories give distributions of impacts on the aperture and the collimators. Then, this distribution is used by FLUKA to simulate the energy deposition on the Magnet Coils and the BLM response. In this case at 4 TeV, it corresponds to a peak loss rate of 1.6e12 p/s (1MW).
The BLM signal simulated from the propagation of secondary showers in the FLUKA geometry was compared to the real BLM signal measured in the LHC, showing an excellent agreement.
It has to be noted that, in simulations, the losses in BLMs and the energy deposited in elements can be different.
Comparison between simulated and real beam losses for Beam 2 (coming from the right). The TCP is the point of highest losses around 200m.
