1. Possible Layout of Positron Target Region Peter Sievers and Kaoru Yokoya 2016.4.19 MiniWS, KEK 2016/4/19 Target Region Layout, Yokoya 1

2. Positron Target Region The most complex region Beamlines Photon  positron capture  acceleration Dogleg of for colliding beam Electron RTML line Dump line of spent electron for 10Hz operation Auxiliary positron source Beam dumps Photons/electrons after positron capture Emergency dump (start just before undulator) Target Special shielding Replacement by remote control system 2016/4/19 Target Region Layout, Yokoya 2

3. Beamline Geometry TDR does not show dimensions of magnets and dumps The components in the first 18m are Flux concentrator (3.2T  0.5T) 2x1.27m (11cell, 15MV/m) SW 3x4.3m (50cell, 8.5MV/m) TW Both surrounded by 0.5T solenoids 3 2016/4/19 Target Region Layout, Yokoya

4. Consensus among ILC positron team No human access needed during high-energy beam on (normal operation and commissioning) Photon/electron dumps must also be shielded 2016/4/19 Target Region Layout, Yokoya 4

5. Target Replacement in TDR 2016/4/19 Target Region Layout, Yokoya 5 Jia Xuejun, KILC12, Daegu

6. 2016/4/19 Target Region Layout, Yokoya 6

7. Horizontal or Vertical Horizontal ISIS target concept Hot-cell very expensive Complicated hydraulics, interlock systems Long period requirement Difficult to engineer Vertical Whole plug replacement Hot-cell but plug storage pit (or area) Short period requirement Less shielding, less tunneling All connections hands-on Jia Xuejun, KILC12, Gaegu 2016/4/19 Target Region Layout, Yokoya 7

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9. Lay Out of the ILC-e+ Target Station Peter Sievers, CERN A Suggestion 9 2016/4/19 Target Region Layout, Yokoya

10. 1. General Strategy The components around the target, along the beam line, are embedded in side (and top?) shield. Purpose of the shielding around the activated components: a) Protect the tunnel, its concrete walls and auxiliary components ( cable trays,…) from radiation damage, corrosion, etc. b) Allow personnel, after appropriate cool down time, to pass and work short times along the passage through the tunnel. c) Protect environment ( ground water, service tunnel,…) against activation. 10 2016/4/19 Target Region Layout, Yokoya

11. 2. Infrastructure Target station should be housed in a horizontal tunnel ( floor and roof). An overhead crane of about 25 t should be provided, to service the target station. The crane is parked in a radiation free zone. Access with special service vehicles to the target station should be possible. The services from the service tunnel to the target components are located in trenches in the floor across the tunnel, which are closed by mobile covers. 11 2016/4/19 Target Region Layout, Yokoya

12. 3. Lay Out 12 2016/4/19 Target Region Layout, Yokoya

13. Photon Dump Two windows after the switchyard bend and at the front face of the dump. The beam goes through air for a while. Specification of the photon dump should take into account the case when the undulator photons directly go to the dump without the target TDR states Photon intensity 2 x 10 17 photons/sec, 10MeV average, angular spread 3  rad. Distance 500m from middle of undulator to target, plus 150m (?) from target to dump  0.5kW/cm 2 on window   T=425 deg on window after one bunch train,  T=190deg in water. Dump: 10cm diameter, 1m long water vessel (12 bar) with 1mm Ti window 2016/4/19 Target Region Layout, Yokoya 13

14. View in Beam Direction The horizontal free space around the beam line is tentatively 0.8 m. The diameter of the vacuum tank of the wheel of 1.2 m is partially cutting into the side shield. The space of 0.8 m for the FC, being integrated into the vacuum tank of the wheel, tbc. 0.8 m for the accelerating cavity, tbc. Beam dump core: only the actual hot core of the dump is considered as a module. Additional side, top and end shielding are part of the global stationary shielding. e+ is the chicane, to bypass the dump core. The chicane is placed such to allow access for the crane hook to the dump and for its lift off before transferring it horizontally out of its support, and this without removal of the chicane. IP- and Tune Up dump lines, as foreseen. With access by personnel? Side shielding (Thickness and material?). Top shielding can be added, if required. Roof and hook height has to be adapted. 14 2016/4/19 Target Region Layout, Yokoya

15. 4. Top View 15 2016/4/19 Target Region Layout, Yokoya

16. The lateral dimensions are tentative to scale, the longitudinal dimensions are not scaled. The target, the FC, the accelerator, the dump core and the e+ chicane are indicated. The thin vacuum window in front of the dump requires careful design. The photon beam passes a short distance through air before entering the dump. The mobile shields are arranged in blocks to be removed by the crane and to liberate the access to a faulty module. 16 2016/4/19 Target Region Layout, Yokoya

17. 5. Removal of a Module 17 2016/4/19 Target Region Layout, Yokoya

18. Scenario for the exchange of a target module. 1. The mobile shield blocks I and II beside the faulty target/FC module are removed by the remotely controlled crane and parked in a convenient place in the tunnel. 2. A versatile, remotely controlled (robotised?) service vehicle is manoeuvred into place, possibly by an operator in a shielded cabin. 3. The vacuum flanges and the supply connections are disconnected. If required, the service vehicle and the overhead crane can work simultaneously on the flanges and the connections. Today, delicate medical surgery is performed remotely in hospitals. So, this should be possible as well in the target area. Industry should be consulted. 4. Once all connections are opened, the service vehicle is driven away and the shielded transport vehicle is put into place. 5. The width of this transport vehicle is tentatively about 2.5 m. The shielding thickness ( heavy concrete, steel, lead) of about 0.5 m should be sufficient, to absorb the remnant activity from the components (tbc). 6. The crane transfers the module into the shielded transport vehicle and drives it away into an outside, safe storage area. The reverse procedure serves to install a spare module. 18 2016/4/19 Target Region Layout, Yokoya

19. 6. Comments In general, it is preferred to remove and exchange only “operating” components, for which a risk of break down exists. Inert components, like shielding, even when cooled by air or water, can be considered as “inert” and should, during interventions, remain stored in the tunnel. The air condition in the target zone is important: closed circuit with heat exchangers and filters? Clean and dry air is important, to prevent condensation and corrosion. Production of Tritium and 7Be, …..must be studied. The water treatment plant for the cooling of the target, FC, accelerator and finally the dump is big: heat exchangers for several 100 kW: purification, filtering, decontamination, recombination after hydrolysis and temporary storage of activated water. Sufficient space for this installation must be foreseen in the service tunnel. Many other beam transport items ( dipoles for the e+ chicane, additional vacuum flanges, fast acting vacuum valves, beam instrumentation, the e- dump downstream of the AMD and the 10 Hz scheme,…) have not yet been considered. 19 2016/4/19 Target Region Layout, Yokoya

20. Remaining Problems Dimensions for Various shields Cavities, solenoids dumps Where should the RTML line go? Space (width) for transport vehicle. ML tunnel reserves 2.1m for vehicle + human path Human path needed due to safety principle Shield thickness during transportation. 20 2016/4/19 Target Region Layout, Yokoya

21. Further Questions from Peter Do we want a "Target-Out" position (not trivial to engineer) for special tests. Or the target is broken? As a general rule: safety may require that a beam dump must be able to take the full beam, at least for a certain time. This is the worst case for the dump, and should be decoupled from the presence of the target. What happens when the emergency kicker upstream of the undulator or that downstrem of the AMD fail? 2016/4/19 Target Region Layout, Yokoya 21

22. 2016/4/19 Target Region Layout, Yokoya 22 From Ewan