1. Cosine-theta configurations for S.C. Dipole Massimo Sorbi on behalf of: INFN LASA & Genova Team Giovanni Bellomo, Pasquale Fabbricarore, Stefania Farinon, Vittorio Marinozzi, Massimo Sorbi, Giovanni Volpini Eurocircol annual meeting, Orsay, 19-20 November 2015

2. INTRODUCTION We explored more configurations and conductors lay-out for cos-theta dipole. Main constrains: -Bore inner diameter50 mm -Bore nominal field16 T -Operating temperature4.5 K -Nominal op. point on load linemax 90% resp. to critical surf. (   T=1.7 K) -Strand max diam.  1 mm -Max strand N./cable40 -Nominal insul. thick.0.15 mm -Layer N. per cable type2 (double pancake) -Yoke outer radius (single apert.)275 mm -Field qualityb3,b5,…< 1 unit -Fringing field (out of cryostat?)<0.1 T Additional preliminary constrains (to be confirmed): Collar thickness30 mm Cu/S.C.≥ 1 90% 100%

3. Magnet characteristic: Op.Current 10700 A Coil out.rad. 80 mm Peak field 16.3 T (blc 3) 95.3 % load line @ 4.5 K Peak field 12.9 T (blc 6) 92.5 % load line @ 4.5 K Turn n/quad. Layer 115 Layer 224 Layer 334 Layer 433 NI/quad1.13 MAt Conf. - INFN-1 2+2 layers 2 cable types: cable1 cable2 N. Strand28 32 Str. diam. (mm)10.7 Cu/S.C.11.5

4. Magnet characteristic: Op.Current 12700 A Coil out.rad. 95 mm Peak field 16.2 T (blc 4) 91.5 % load line @ 4.5 K Peak field 12.6 T (blc 8) 90.7 % load line @ 4.5 K Turn n. Layer 114 Layer 222 Layer 333 Layer 437 NI/quad1.35 MAt Conf. - INFN-2 2+2 layers 2 cable types: cable1 cable2 N. Strand4040 Str. diam. (mm)10.7 Cu/S.C.11.5

5. Magnet characteristic: Op.Current 12200 A Coil out.rad. 95 mm Peak field 16.2 T (blc 3) 91.4 % load line @ 4.5 K Peak field 12.1 T (blc 8) 87.5 % load line @ 4.5 K Turn n. Layer 117 Layer 229 Layer 333 Layer 440 NI/quad1.45 MAt Conf. - INFN-3 2+2 layers 2 cable types: cable1 cable2 N. Strand4040 Str. diam. (mm)11 Cu/S.C.12.1

6. Conf. - INFN-3 2+2 layers Iron yoke external Radius = 400 mm (for single aperture)

7. Magnet characteristic: Op.Current 5251 A Coil out.rad. 88 mm Peak field 16.2 T (blc 3) 88.5 % load line @ 4.5 K Peak field 14.02 T (blc 9) 90.0 % load line @ 4.5 K Peak field 12.79 T (blc 11) 90.0 % load line @ 4.5 K Turn n. Layer 116 Layer 221 Layer 336 Layer 449 Layer 557 Layer 665 NI/quad1.28 MAt Conf. - INFN-4 2+2+2 layers 3 cable types: cable1 cable2cable3 N. Strand203838 Str. diam. (mm)10.530.53 Cu/S.C.11.272.1 Weight av.: 1.76

8. Type Cable str. N. Str.diam. (mm) Cu/S.C.Rcoil-out. (mm) Current (kA) Operating point on load line (%) Energy (MJ/m) L (mH/m) En./cond (J/mm 3 ) Tot. strand area (mm 2 ) NI (MAt) 4 layers INFN-1 28 32 1 0.7 1 1.5 8010.7 95.3 (lay.1) 92.5 (lay.3) 1.22210.1867302.26 4 layers INFN-2 40 1 0.7 1 1.5 9512.7 91.5 (lay.1) 90.7 (lay.3) 1.77210.2088342.7 4 layers INFN-3 40 24 1111 1 2.1 9512.2 91.4 (lay.1) 87.5 (lay.3) 1.71220.15112852.90 6 layers INFN-4 20 38 1 0.53 1 1.27 2.1 885.25 88.5 (lay.1) 90.0 (lay.3) 90.0 (lay.5) 1.421020.1592442.56 Summary of configurations: Common parameters: Single bore dipole Bore diam.50 mm Collar thick.30 mm Yoke out. rad.275 mm

9. Consideration on inductance/current for quench protection: For a magnet with energy extraction (dumping resistance) it is preferable to have low inductance and large current (the current constant time is L/Rd) For magnet with negligible energy extraction (our case) the requirement of low inductance and large current does not appear necessary (the current constant time is L/Ri with both L ÷ N 2 and Ri ÷ N 2 ) It may be harder to induce fast transition on internal layers  solutions may be inter- layer heaters or CLIQ Other considerations: The configuration of 6 layers has additional construction complication (1 more splice for cable connections) and construction cost (1 more double pancake) The vantage is reduced dimension for cable (  easier for winding), easier cable “packing” in winding, more critical temperature margin, more control of field quality

10. Two-in-one layout Preliminary considerations for the cross talking: The bore field increases 0.9 T (6%)  current can be decreased 6% The operating margin increase  1% Quadrupole harmonic appear  10-20 unit  not hard to correct (iron machining/holes, asymmetric positioning of conductor)

11. Fringing field consideration The target of 0.1 T is reached at about 400-450 mm from the yoke outer radius=275 mm for single aperture  outside of the cryostat In the double aperture the 0.1 T is reached at about 150-200 mm yoke outer radius=400 mm  now very close outside of the cryostat Single aperture Yoke ext. R=275 mm Double aperture Yoke ext. R=400 mm

12. Conclusions: The space of possible configurations has been explored With the 2+2 layers configurations the target of 90% operating point on load line is almost reached (actually reached for the double aperture) With the 2+2+2 layers configuration the target is reached The required field quality can be reached The explored configurations have to be optimized for construction reliability (conductor positioning, angles, etc.) The mechanical analysis has to confirm the thickness of collars (now 30 mm) Protection studies will have to confirm the choice for Cu/S.C. ratio The passage to double aperture is not challenging from the magnetic point of view  we can focus on single aperture design