8 Accelerator Engineering and Technology: Accelerator Technology
437
The installation of the vacuum system follows the closure of the detector.
Therefore, the design has to be validated beforehand in order to prevent integration
issues which could prevent the closure of the detector and lead to significant delay
and increase of costs. Temporary supports and protection are required at each stage
of the installation. Indeed, as compared to the size of the detectors, the beam pipes
are small, fragile and need to be permanently supported and protected while moving
the detector components.
The leak tightness and bake-out testing are compulsory at each step of the
installation since all vacuum systems are later on encapsulated in the detector,
thereby preventing any access, even for repair. Their reliability is critical.
The installation of the detectors dictates the speed and sequence of installation of
the beam-pipes. To avoid delays, the vacuum components must be available (tested
and ready for installation) in advance in order to adapt to the installation sequence.
The experimental beam-pipe must be thin and manufactured from light material
in order to allow the particles created inside the beam-pipe to escape from it
through the vacuum envelope. Since the detectors are extremely demanding in
terms of operating pressure (normally expressed in gas densities) light materials
are mandatory. Beryllium and aluminium materials are the most commonly used.
Titanium is sometimes an alternative. These materials can be NEG coated by
plasma discharge and baked-out in-situ. Beryllium being is extremely expensive
and dangerous in case the beampipe breaks; beam-pipe design attempts have been
made to replace the beryllium by composite chambers. Carbon-carbon materials
have been used with metallic layers but the ultimate pressure is not yet in the range
of the specification of the modern detectors. The engineering solutions for the bakeouts have also to be studied in details since the bake-out solutions (heaters, probes
and cables) must fit within the limited space available between beam-pipes and the
detector parts.
The excellent performances of the vacuum system in the experimental areas are
a determinant factor for the performances of the detectors themselves. The most
important issues to follow are the beam-pipe transparency, gas density and residual
gas composition, impedance and high order mode trapping and precise alignment.
The last point is difficult to achieve once the beam-pipes are installed in large
detectors.
8.6 Beam Instrumentation and Diagnostics
R. Jones · T. Lefevre · H. Schmickler
Beam instrumentation and diagnostics [117, 118] combines the disciplines of
accelerator physics with mechanical, electronic and software engineering, making it
an extremely interesting field in which to work. The task of a beam instrumentation
physicist or engineer is to design, build, maintain and improve the diagnostic
equipment for the observation of particle beams with the precision required to tune,
437
The installation of the vacuum system follows the closure of the detector.
Therefore, the design has to be validated beforehand in order to prevent integration
issues which could prevent the closure of the detector and lead to significant delay
and increase of costs. Temporary supports and protection are required at each stage
of the installation. Indeed, as compared to the size of the detectors, the beam pipes
are small, fragile and need to be permanently supported and protected while moving
the detector components.
The leak tightness and bake-out testing are compulsory at each step of the
installation since all vacuum systems are later on encapsulated in the detector,
thereby preventing any access, even for repair. Their reliability is critical.
The installation of the detectors dictates the speed and sequence of installation of
the beam-pipes. To avoid delays, the vacuum components must be available (tested
and ready for installation) in advance in order to adapt to the installation sequence.
The experimental beam-pipe must be thin and manufactured from light material
in order to allow the particles created inside the beam-pipe to escape from it
through the vacuum envelope. Since the detectors are extremely demanding in
terms of operating pressure (normally expressed in gas densities) light materials
are mandatory. Beryllium and aluminium materials are the most commonly used.
Titanium is sometimes an alternative. These materials can be NEG coated by
plasma discharge and baked-out in-situ. Beryllium being is extremely expensive
and dangerous in case the beampipe breaks; beam-pipe design attempts have been
made to replace the beryllium by composite chambers. Carbon-carbon materials
have been used with metallic layers but the ultimate pressure is not yet in the range
of the specification of the modern detectors. The engineering solutions for the bakeouts have also to be studied in details since the bake-out solutions (heaters, probes
and cables) must fit within the limited space available between beam-pipes and the
detector parts.
The excellent performances of the vacuum system in the experimental areas are
a determinant factor for the performances of the detectors themselves. The most
important issues to follow are the beam-pipe transparency, gas density and residual
gas composition, impedance and high order mode trapping and precise alignment.
The last point is difficult to achieve once the beam-pipes are installed in large
detectors.
8.6 Beam Instrumentation and Diagnostics
R. Jones · T. Lefevre · H. Schmickler
Beam instrumentation and diagnostics [117, 118] combines the disciplines of
accelerator physics with mechanical, electronic and software engineering, making it
an extremely interesting field in which to work. The task of a beam instrumentation
physicist or engineer is to design, build, maintain and improve the diagnostic
equipment for the observation of particle beams with the precision required to tune,