the cngs target station by l.bruno, s.péraire, p.sala sl/bt targets & dumps section

The CNGS Target Station

By L.Bruno, S.Péraire,

P.SalaSL/BT Targets & Dumps Section

The CNGS Target Station

OUTLINE

1. Driving parameters2. Conceptual & Engineering Design 3. Status in Feb 2002

4. “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 4.8x1013

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).

Conceptual & Engineering Design

Main Issues

Material choice Target Dimensions &

Configuration Efficiency & Structural

Behaviour Optimisation &

Ancillaries

A Glossary related to Targets…

Element - an item made from a single piece of materialperforming a target function, i.e. intercepting a beam of particles.

Unit - a combination of target elements joined together, which could not be disassembled without destruction or impairment of the target function.

Assembly - a number of target units joined together, and subject to disassembly without any degradation of any of the parts.

Station - self-sufficient item in the accelerator environment capable performing and supporting the target function.

Box - Interface between the target assembly and the systems supporting the target function (cooling, alignment, remote handling).

CNGS Target Issues

Temperature / Thermal gradientDynamic effects / Mech. strengthRadiation damage

Target Elements

Target Assembly / BoxRemote Handling External CoolingAlignment

Target UnitGeometrical accuracyBackground / Signal reductionInert atmosphere / ContainmentCooling interface

Temperature / Thermal gradientDynamic effects / Mech. strengthRadiation damage

Target ElementsTemperature / Thermal gradientDynamic effects / Mech. strengthRadiation damage

Target Elements

Target Assembly / BoxRemote Handling External CoolingAlignment



Progress to date

We are here

Done

Target Design : a 3-step engineering approach

1st Step - Select form and type of target elements rods of refractory material(s)

2nd Step - Define a suitable target unit pattern of thin flexible lightweight supports

holding in place accurately the target elementsproviding a “material-friendly” environment

3rd Step - Integrate one or more units in a target assembly / box compact, easily interchangeable piece of equipment

providing cooling, alignment & remote handling

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.

POCO h-BN1940 2020 2333 R7500 CZ3 CZ5 CZ7 ZXF-5Q AX05

Apparent Density g cm-3 1.76 1.77 1.86 1.77 1.73 1.84 1.88 1.78 1.91Open Porosity % 16 9 10 13 14 10 10 16Avg. Grain size µm 12 16 5 10 20 10 3 1Young Modulus Gpa 10 9.2 10 10.5 10 11.5 14 14.5 30Thermal exp. Coeff. µm/m °C 4.7 3.5 6 3.9 3.8 5.1 5.8 8.1 0.5Thermal Conductivity W/m°C 81 75 90 80 65 100 100 71/121 Electrical resistivity µ m 16.5 14 18 13 13 19.5 > 1014

Specific heat J/kg °C 710 710 710 710 710 710 710 710 800Flexural strength MPa 45 41 76 50 40 60 85 115 22Compressive Strength MPa 91 100 167 120 90 125 240 195 23Tensile strength MPa 30 27 50 33 26 40 56 76 15

Ratio c/t - 3.1 3.7 3.3 3.6 3.4 3.2 4.3 2.6 1.5K ~ (t Cp)/(E ) - 0.45 0.60 0.59 0.57 0.49 0.48 0.49 0.46 0.80

Graphites and hBN - Material Properties at 20 °C

SGLProperty Unit

Carbone-Lorraine

Material Choice 2/2

σt cp,avg

E ασt cp,avg

E αK

Thermo-mec hanical Efficiency

The change of properties with temperature was considered in the comparison between the different materials.

0

5

10

15

20

25

30

35

0 250 500 750 1000 1250 1500

Temperature [°C]

Yo

un

g M

. [G

Pa

]

/ σ

t [M

Pa

]

0

1

2

3

4

5

6

Cp [

kJ

/kg

°C]

α

[µ

m/m

°C

]

α

cp

E

σt

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 s

cale

)

R [

cm]

Z [cm]

Target Heat Load

0

20

40

60

80

100

120

140

160

1 2 3 4 5 6 7 8 9 10 11 12 13

Rod No.

Avg

. The

rmal

Pow

er [W

]

Nominal Ultimate

Beam intensity 4.8 10 13 p 7 10 13 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

Ti TubeTi Window

Ti Window

Target elements

Inert gas

Radiation + Convection

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

0

100

200

300

400

0 0.5 1 1.5 2 2.5

0

5

10

15

20

Off-axis beam displ. [mm]

Th

erm

al D

efle

ctio

n [

µm

]

Ma

x S

tass

iStr

ess

[M

Pa]

371 µm371 µm

15.7 MPa15.7 MPa

Centred Beam

Grazing Beam

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

0

2

4

6

8

10

12

14

16

18

20

0 20 40 60 80 100

Time [µs]

Ma

x S

tass

iStr

ess

[M

Pa]

15.7 MPa15.7 MPa

Centred Beam

Off-axis beam

6.5 MPa6.5 MPa

Reflected tensile wave

1st compr. wave

2nd compr. wave

Sound Speed = 2.4 mm/µs

Sound Speed = 2.4 mm/µs

+ ~70%

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

ID T ask Name1 Target Element

7 Eng. Design Activ ities

8 Preparation

9 T arget Box + Motoris .

10 Shielding

11 Cool ing Stati on

12 Remote Handli ng

13 Heating tes ts

14 Fabrication

15 Target Box

16 Market survey

17 Spec if ication

18 Call for tenders

19 Order + Fabricati on

20 Delivery + T ests

21 Assembly

22 Ins tall at ion

23 Shielding

24 Market survey

25 Spec if ication

26 Call for tenders



29 Montage a blanc

30 Ins tall at ion

31 Cooling Station

32 Market survey

33 Spec if ication

34 Call for tenders



37 Ins tall at ion

38 Control

Qtr 4 Qtr 1 Qtr 2 Qtr 3 Qtr 4 Qtr 1 Qtr 2 Qtr 3 Qtr 4 Qtr 1 Qtr 2 Qtr 3 Qtr 4 Qtr 1

2001 2002 2003 2004 2005

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 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.

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

PBS 1.5 Target Station (Code 93730 ) NOTE: All cost in kCHF

Item Description Details Estimate status

Contract Type Contingency Risk of Overrun 01 02 03 04 05GrandTotal

Design Cost Estimate 0 200 0 0 0 200

Eng. Studies Numerical Studies None 0 0 0 0 0 0

EST 2000 h J 2 10% Low 90 90 EST 1000 h D 2 10% Low 45 45

Tests Material & Heating 20% Medium 0 65 0 0 0 65

Manufacture Cost Estimate 0 0 500 855 165 1520

Box Box + Units D A 20% Medium 120 150 40 310 Motorisation Motors, Potentiom. D A 10% Low 10 10 20 Shielding D A 10% Low 270 490 50 810 Cooling Station D A 10% Low 60 120 20 200 Small Items D 1 20% Medium 10 10 10 30 Hardware PLC, racks etc. D A 10% Low 8 20 12 40 Cabling 6 cab. x 1 km D A 10% Low 12 30 18 60 Manpower 0.5 man/year D A 10% Low 10 25 15 50

Installation Cost Estimate 0 0 0 20 10 30

Cost Estimate 0 200 500 875 175 1750 % 0 11 29 50 10

Design office

Total

Target Box

Ancillary eq.

Control

Budget - 2/2

19%

11%

11%48%

2%9%

Shielding

Design

Cooling

Target

ControlOther

the cngs target station by l.bruno, s.péraire, p.sala sl/bt targets & dumps section

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