The CNGS Target Station

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The CNGS Target Station
By L.Bruno, S.Péraire, P.Sala SL/BT Targets
Dumps Section
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The CNGS Target Station
OUTLINE 1. Driving parameters 2. Conceptual
Engineering Design 3. Status in Feb 2002
4. Risk Analysis 5. Summary
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Driving Parameters
The CNGS Target has to
reliably intercept a 400 GeV proton beam every
6 s in a double fast extraction with 10 µs long
spills at 50 ms distance. The nominal beam
intensity is 4.8x1013 protons per cycle, but an
ultimate intensity of 7x1013 protons must be
considered in view of a possible beam upgrade.
The beam has a normalised emittance of 12? mm
mrad and a ? to be optimised (starting value is
0.27 mm).
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Conceptual Engineering Design

• Main Issues
• Material choice
• Target Dimensions Configuration
• Efficiency Structural Behaviour
• Optimisation Ancillaries

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A Glossary related to Targets
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CNGS Target Issues
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Progress to date
Done
We are here
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Material Choice 1/2
A wide range of graphites was investigated. Based
on material data available in literature, the
best candidates have been identified. The table
shows a selection of grades considered.
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Material Choice 2/2
The change of properties with temperature was
considered in the comparison between the
different materials.
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Optimisation
Optimised value
WARNING beam size is critical !!!
(P.Sala)
(P.Sala)
A thorough and lengthy study was performed to
optimise the Physics and Engineering of the
target unit. A huge variety of alternatives for
geometry, configuration and beam size was
investigated before the most promising solution
was singled out.
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Target Configuration
R cm
90 mm
? 4 mm
? 5 mm
Proton Beam
(Not to scale)
100 mm
480 mm
(P.Sala)
Z cm
The amount and quality of the design work can be
estimated from the details of the selected target
configuration.
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Target Heat Load
The heat load in each of the target elements is
comparable to that of light bulbs. This is low
enough to simplify the cooling system and use gas
convection and thermal radiation.
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Target Unit - Concept 1/2
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Target Unit - Concept 2/2
Tube (Titanium)
Support Frame (C-C composite)
Window (Titanium)
Beam
Target elements (Graphite)
 Cards  (C-C composite)
Sleeve (C-C composite)
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Target Element
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Target Element
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Target Unit
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Temperature increase in a Ti target tube
The target heat load is limited mainly to the
target elements. The surrounding tube is not
significantly heated.
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Fault tolerance 1/3
The physics of the CNGS target is robust enough
to tolerate significant alignment errors without
a decrease in particle production.
Energy-weighted pion production as a function of
beam ? and target diameter for a 0.2 mm
displacement of the beam
(P.Sala)
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Fault tolerance 2/3
The engineering of the CNGS target is robust
enough to tolerate significant alignment errors
without exceeding the allowable stress in
graphite
Quasi-static thermal deflection and Max Stassi
stress as a function of beam misalignment in the
first target rod.
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Fault tolerance 3/3
In the worst misalignment case the dynamic stress
is within the allowed range.
Dynamic Max Stassi stress for the worst
misalignment case in the first target rod
compared to the case of centred beam.
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Further validation of the Design
There is still work to be done !
Further design studies by numerical modelling of
the overall heat exchange, geometrical stability,
structural resistance and asymmetries Experimenta
l validation of the material choice (mechanical
thermal fatigue tests) Study of the thermal
equilibrium by a full-size mock-up of a Target
Unit with electrical heaters (d.c. and
pulsed) Address open issues in the ancillary
equipment windows, in-situ spares, remote
handling, shielding
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Schedule
WARNING The schedule for the technical study and
tests is tight
Target Box
Shielding
WARNING Shielding fabrication is lengthy
Cooling system
Control
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Summary
The design of the CNGS Target fulfils the
specification. In view of a possible beam
upgrade, it allows an increase of beam intensity
up to 7x1013 protons. A wide range of design
alternatives for target material, geometry,
configuration and beam size was investigated to
single out the most promising solution. The heat
load in the Target Unit is limited enough to
simplify the cooling system. The physics and
engineering of the Target are robust enough to
tolerate significant alignment errors. Presently,
the technical study of the Target Unit is being
performed. The activity is on budget and on
schedule.
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Rationale for Schedule and Budget
T1
T9
The budget and planning for the CNGS Target
Station are based on the past experience in
building the T1 Target Station and the West Area
Neutrino Facility (T9).
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Budget 1/2
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Budget - 2/2
Other
Control
Target
Cooling
Shielding
Design