2007 2008 ACADEMIC TRAINING PROGRAMME
LECTURE SERIES
13 May 2008
11:00 -12:00 – Main Auditorium, bldg. 500-1
LHC Hardware Commissioning - Why LHC Hardware commissioning? Specificity and complexity of the LHC
Roberto SABAN, CERN, Geneva
The operation of the Large Hadron Collider relies many systems with technologies often beyond the start of the art and in particular on hundreds of superconducting magnets operating in superfluid He at 1.9K powered by more than 1700 power converters. A sophisticated magnet protection system is crucial to detect a quench and safely extract the energy stored in the circuits (about 1GJ only in one of the dipole circuits of each sector) after a resistive transition.
In order to ensure safe operation, these systems depend on each other and on the infrastructure systems (controls, electricity distribution, water cooling, ventilation, communication systems, etc.). The commissioning of the technical systems together with the associated infrastructures is therefore mandatory.
The complexity of operating this machine stems from the dependence and interplay of the systems, their nominal performance which is often at the technological frontier and on their geographical distribution.
14 May 2008
11:00 -12:00 – Main Auditorium, bldg. 500-1
LHC Hardware Commissioning - The challenges for getting the nominal cryogenic conditions
Laurent TAVIAN, CERN, Geneva
The cooling of the LHC is produced by eight large cryogenic plants – one per sector - installed in five cryogenic islands. Each plant is able to produce up to 600 kW at 80 K, up to an equivalent capacity of 18 kW at 4.5 K as well as up to 2.4 kW at 1.8 K. After cooling the huge sector mass of 4.6x106 kg from room temperature down to 1.9 K and filling the magnet with up to 15 tons of helium mainly in superfluid state, the cryogenic system must be tuned without current to obtain stable operating conditions over long period. Following this tuning, powering tests with current ramping and de-ramping, fast current discharges and resistive transitions are performed. Fast discharges of the current of the main magnet circuits dissipate up to 3 kJ per meter in the magnet cold-masses which must remain cooled in superfluid helium. Resistive transitions of magnets create fast pressure and temperature rises and flow surges. Following a resistive transition of a magnet cell (107 m), the recovery time to nominal conditions should not exceed few hours.
15 May 2008
11:00 -12:00 – Main Auditorium, bldg. 500-1
LHC Hardware Commissioning - The challenges of protecting the super-conducting magnets and powering system
Karl-Hubert MESS and Rudiger SCHMIDT, CERN, Geneva
Unprecedented parameters of the LHC accelerator have a significant impact on operation and machine protection. The energy stored in the magnets is in the order of 10 GJoule when operating at 7 TeV. Each beam carries an energy of about 360 MJoule at nominal beam current. LHC powering operation, and later beam operation must fully rely on a number of protection system.
For powering of the superconducting magnets, the quench detection system, the system to extract the energy and the related interlock systems are required to prevent magnets and other powering equipment to be damaged in case of a quench, or other accidents. During hardware commissioning, the systems must be fully tested. This will not only guarantee that the equipment is protected, but also ensure that the machine is ready for beam and pave the way for the commissioning of beam related protection systems, such as beam interlocks, beam dumping system and beam loss monitors.
16 May 2008
11:00 -12:00 – Main Auditorium, bldg. 500-1
LHC Hardware Commissioning - The challenges of powering the super-conducting magnets
Quentin KING, CERN, Geneva
The LHC machine requires more than 1700 power converter systems that supply between 60A and 12kA of precisely regulated current to the superconducting magnets.
In addition to the power converters themselves, utilities (such as air and water cooling, electrical power, communication networks,…) and superconducting elements (current leads, magnets, busbars,…) with their safety systems needed to be commissioned as a single system.
Due to the complexity of commissioning, the power converters with inevitable interaction between the different systems and to guarantee the very high precision (few ppm) required by the beam performance, a three phase test strategy was developed. The first phase comprises the manufacture, integration and reception tests of all systems necessary for high precision power converters (voltage source, current transducers and high precision electronics). The second phase covers the commissioning of all the power converters installed in their final environment with the utilities and with all normal conducting elements on a short circuit. And finally the third phase adds the superconducting magnets.
The presentation will quickly summarized the results and conclusions of the power converter reception tests and the short-circuit tests and will focus on the hardware commissioning of the converters powering the superconducting magnets.
19, 20, 21 May 2008
11:00 -12:00 – Main Auditorium, bldg. 500-1
Black holes and neutron stars
Dr. Adam BURROWS, Princeton University, USA
Modern supernova simulations suggest that one or more of three general classes of explosion mechanisms are employed by Nature to end the life of a massive star and to give birth to neutron stars and black holes. These are the neutrino, acoustic, and MHD mechanisms. However, though the computer codes currently applied to this puzzle incorporate the requisite physics with increasing fidelity, they are not yet able to settle the question. Moreover, it is now clear that the Gamma-Ray Burst phenomenom and the supernova phenomenom are related, however distantly. I will present results of various simulations, the physics behind them, and predictions concerning the gravitational-wave, neutrino, and pulsar signatures of various scenarios. The goal is to summarize where the theory that subsumes supernova explosions, GRBs, and the birth of compact objects is and where it is going.
