The CNGS Target Station By L.Bruno, S.Péraire, P.Sala SL/BT Targets & Dumps Section

The CNGS Target Station OUTLINE 1. Driving parameters 2. Conceptual & Engineering Design 3. Status in Feb “Risk Analysis” 5. Summary

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 4.8x10 13 protons per cycle, but an ultimate intensity of 7x10 13 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).

Conceptual & Engineering Design Main Issues  Material choice  Target Dimensions & Configuration  Efficiency & Structural Behaviour  Optimisation & Ancillaries

A Glossary related to Targets…

CNGS Target Issues

Progress to date We are here Done

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.

Material Choice 2/2 The change of properties with temperature was considered in the comparison between the different materials.

Optimisation (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. (P.Sala) WARNING: beam size is critical !!! Optimised value

Target Configuration Proton Beam 100 mm 90 mm 480 mm  4 mm  5 mm The amount and quality of the design work can be estimated from the details of the selected target configuration. (P.Sala) (Not to scale) R [cm] Z [cm]

Target Heat Load Nominal Ultimate Beam intensity p p Total Power~ 900 W ~1400 W 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.

Target Unit - Concept 1/2

Target elements (Graphite) « Cards » (C-C composite) Sleeve (C-C composite) Tube (Titanium) Support Frame (C-C composite) Window (Titanium) Beam Target Unit - Concept 2/2

Target Element

Target Unit

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.

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)

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.

Fault tolerance 3/3 Dynamic Max Stassi stress for the worst misalignment case in the first target rod compared to the case of centred beam. In the worst misalignment case the dynamic stress is within the allowed range.

Further validation of the Design Further design studies by numerical modelling of the overall heat exchange, geometrical stability, structural resistance and asymmetries; Experimental 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… There is still work to be done !

Schedule WARNING: Shielding fabrication is lengthy Shielding Cooling system Target Box Control WARNING: The schedule for the technical study and tests is tight

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 7x10 13 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.

Rationale for Schedule and Budget 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). T1 T9

Budget 1/2

Budget - 2/2 Shielding Design Cooling Target Control Other