CERN: LHC Virtual Visit
LHC – the aim of the exercise: To smash protons moving at 99.999999% of the speed of light into each other and so recreate conditions a fraction of a second after the big bang. The LHC experiments try and work out what happened.
The Large Hadron Collider (LHC) sits in a circular tunnel 27 km in circumference. The tunnel is buried around 50 to 175 m. underground. It straddles the Swiss and French borders on the outskirts of Geneva.
The first collisions at an energy of 3.5 TeV per beam took place on 30th March 2010.
The LHC is designed to collide two counter rotating beams of protons or heavy ions. Proton-proton collisions are foreseen at an energy of 7 TeV per beam.
* The beams move around the LHC ring inside a continuous vacuum guided by magnets.
* The magnets are superconducting and are cooled by a huge cryogenics system. The cables conduct current without resistance in their superconducting state.
* The beams will be stored at high energy for hours. During this time collisions take place inside the four main LHC experiments.
The goal of the Linac4 project is to build a 160 MeV H? linear accelerator replacing Linac2 as injector to the PS Booster (PSB) and to modify the PSB injection for the Linac4 beam. The beam brightness out of the PSB is expected to increase by a factor of 2.
Linac4 is designed to become the first section of a low-power Superconducting Proton Linac (SPL) replacing the PSB. It will be located in a building that allows the extension to the SPL without interruption of physics, and could be upgraded to higher duty cycle for a high-power SPL if required by the physics programme.
The PSB will deliver beam for physics using the new injector at start-up 2013, reaching its maximum performance after a few years of operation.
Linac4 is composed of an ion source, a Front-end (Radio Frequency Quadrupole and a chopper line), an Alvarez Drift Tube Linac (DTL), a Cell-Coupled Drift Tube Linac (CCDTL) and a Pi-mode structure (PIMS), for an overall length of 86 metres. A 70 m long transfer line joins the present Linac2 to PSB line. The RF accelerating structures will operate at 352.2 MHz frequency, re-using some RF equipment from LEP (klystrons, circulators and waveguides) and taking advantage of existing RFQ technology. Charge exchange injection will be implemented in the PSB, together with the modifications required in the PSB injection line to cope with the higher injection energy.
Although the duty cycle for the PSB and for the low-power SPL does not exceed 0.1%, all the accelerating structures are designed for a maximum duty cycle of 5%, to allow for future operation of Linac4 as the first part of the high-power SPL. Most of the hardware components (accelerating structures, magnets, RF high-power components, etc.) will be built for high duty cycle operation, while electronics (power supplies, etc.) and infrastructure (cooling, electricity) will be dimensioned for the low duty cycle. Linac4 will be able to operate without modifications for the low-power SPL (LP-SPL).