Introduction

1. Introduction • I don’t like the explicit mention of experiments in Ian’s question • Compartmentalizing into experiments has been always one of the things we did wrong in this department • Rather, to map out the future of the Silicon hardware activities we should focus on technologies • Oxford is large enough to do that • With the best technology we can become the leaders in (m)any experiment(s) • Many of the challenges (minimum mass, cost-saving technologies, fast and cost-saving integration) are independent of the experiment • So, I’ll describe the programme as the Future Ideal Tracker (FIT) in three phases • FIT1: in 10y • FIT2: in 20y • FIT3: in 30y • Final point: My interest (bias) is clearly in mechanics, cooling, services, integration and project management – I know even less about sensors, electronics and read-out

2. #1 • What should the strategy for the sub-department be to prepare for the possibility (hypothetical at the moment) that the FIT2 is announced to go forward in January 10, 2017? This strategy would mostly be concerned with detector designs and their eventual fabrication especially vertex detector and tracking and the machine detector interface. It should be as explicit as possible. It should take into account the national and international context. • Whatever experiment we do, we should do what our capabilities are particularly suited for, and where not everybody else wants to go • I think this is all aspects of large volume Silicon trackers • Vertex systems might be still something to participate at lower level (for the fun) • (If you want to think about the ILC, this means that we need to nail our flag to the mast about the type of detector we want to participate in) • It is essential that we are part of a strong UK tracker group • Our impact will be much greater • We will not end up with knives in our back • The goal should be to play a major defining role in the international FIT2 community, have responsibilities in the construction of this system, and use this role to make sure that UK industry can contribute to this tracker

3. #2 • What should the strategy for the subdepartment be re: FIT3 ee and pp options? At this stage in the FIT3 development the strategy would be concerned mostly with simulations of the detector and the physics case. • Formulate an aggressive vision of how we dream FIT3 could or should look like and build up a programme towards it (via FIT1 and FIT2) • In parallel, if there are people with time and interest available, we can study what the performance of this vision could be • However, I do think that there is more immediate work on tracking, alignment and simulation (in the context of FIT1 and FIT2), which would require effort and will gain us expertise, recognition and impact, which ultimately will benefit us in FIT3

4. #3 • What areas are synergistic between FIT1 and FIT2 and (optionally FIT3) that you would be personally be interested in helping to develop? • It should have become clear that I see this as one continuous programme • As mentioned above my personal interests are in mechanics, cooling, services, integration and project management • One additional remark: There will be other projects, which do not belong to the immediate FIT programme, but still could be interesting, be compatible with our capabilities (and might bring money) and we should participate in these as well

5. If there is time and interest…

6. What could be the vision? • Future sensor technologies (thinned down MAPS) promise material down to a few ‰ of a radiation length • Structures and services need to match this • We do have a strong preference for liquid (evaporative) cooling • Gas cooling is not a robust technology (difficult to predict) • Gas cooling has limited capacity (might be ok for linear collider, but not much more) • For comparison: ATLAS phase II >2.5% X0, LC TDR ~1% X0 • Support/service sandwich layer: • Structural: UHM fibre (e.g. K13C2U, 4 layers of 45gsm) • Cooling: MicrochannelKapton cooling • Electrical services: Al/Kapton multilayer cables • All the above are co-cured (this saves glue) • Sensors: Thinned down to 50µm (MAPS) • This would be a layer less than 1mm thick → Challenge: Is 0.5% X0/tracking layer with evaporative cooling possible for a large ((2-3m)3) tracker? Sensor Al/Kapton tape 90° Of course, we have ignored a few things, but we think 0.5% is a conceivable aspiration… UHM CF 0° Kapton microchannels 0° UHM CF 6 90°

7. Kapton microchannel cooling • Developed for ALICE by CERN: • Tested to 10bara with water and C6F14monophase cooling • Requires scaling to large tracker size, can we achieve higher pressures • At Oxford we have started to look into similar photo-etched and machined structures… G. Fiorenza et al., 5th IEEE International Workshop on Advances in Sensors and Interfaces (IWASI), 2013, p. 81-85, 10.1109/IWASI.2013.6576065. 7

8. How can we achieve stiffness? • The key is design for large moment of inertia (together with high modulus) • Ladders are poor • Large cylinders are better • But: hoop stiffness is now the challenge • Also: integration of large cylinders has many disadvantages • Large, valuable objects – difficult to move/transport • Technologies get challenged late in the integration • Can one make smaller units which are clever structurally? • Yes, exploit the mouldability of CF (and Kapton-based service elements)! • Examples exist for vertex/pixel systems, need to scale by 10 in size • And, with 50μm sensors, the structures do not need to be flat… ALICE, doi:10.1016/j.nima.2006.04.093 BNL, doi:10.1016/j.nima.2013.07.005 STAR, doi:10.1016/j.nima.2010.12.006 8