INTRODUCTION

CERN is the European Organization for Nuclear Research. Founded in 1954, it is the largest particle physics center in the world. Located on the border of France and Switzerland, CERN provides research opportunities to scientists of at least twenty different Member States. At CERN, researchers are given the opportunity to use state-of-the-art accelerators, which are the main equipment for research focused on high-energy particle reactions. CERN’s ongoing commitment for the past 48 years is to explore what matter is made of, as well as what interactions between constituents of matter.

As particle physics heads towards the 21st century, its focus is evolving from seeking the basic constituents of matter to discovering why these constituents act and react they way they do. The Large Hadron Collider (LHC), being built at CERN, is the machine that will take particle physicists into this exciting new phase of discovery.[1] The LHC will collide high-energy proton beams at an energy of 14 TeV, allowing the production of particles with masses up to be 1 TeV/c².

High-energy LHC beams need strong magnets to bend the beam around the desired path. To bend 7 TeV protons around a 15km diameter ring, the LHC dipoles must be able to produce fields of 8.36 Tesla; over five times those used a few years ago at the SPS proton-antiproton collider, and almost 100,000 times the earth's magnetic field.

Superconductive materials make this possible. Superconductivity is the property of certain materials, usually at very low temperatures, to conduct electric current without resistance and power losses, therefore producing high magnetic fields. For comparable power consumption, the LHC can delivery 25 times the energy and 10,000 times the luminosity of the SPS collider.[2] The figure shown below is a model of one of the many superconducting dipole magnets that will be utilized in the LHC project.  

Figure 1: This picture represents the model of a superconducting dipole magnet for the LHC project.

(Courtesy of CERN; http://public.web.cern.ch/Public/TECHNOLOGY/techpict3.html) 

The rising dilemma of use of superconducting magnets revolves around the strength of the magnet. The new LHC magnets are many times more powerful than any used previously, hence new methods and new technology must be developed. One such method that was used in the SPS collider requiring modification is that of mapping the magnetic field. Since no two magnets can be manufactured identical at an atomic level, small imperfections are introduced into every magnet. While the average magnetic field may remain constant, some magnets produce stronger magnetic fields than others, and the magnetic field may deviate depending on such imperfections in the magnet itself.

A clear mapping of the magnetic field is crucial for data collection. With knowledge of the fluctuations of the magnetic field and where they occur, allowances for errors in the data from the LHC can be accounted for. The mapping of the magnetic field also allows for a quick reference to determine if certain magnets need to be replaced.