1. Low-mass Detector Systems: Materials for Future Detectors Carl Haber (LBNL) Bill Cooper (FNAL)

2. General Considerations Low-mass systems and low-mass materials for them represent slightly different topics. In the lowest-mass systems, active elements (sensors), support structures for them, and readout and services should be closely integrated. Indeed, sensors can serve as portions of their own support structure, thereby reducing the need for additional materials. That approach can be extended to cooling, where, for some detectors, sensors would dissipate their heat and heat associated with their readout directly into cooling gas. Both of those approaches have been adopted in some collider systems, such as the silicon system for SiD. We should be careful not to limit our thinking by considering sensors, readout, support structures, and services separately rather than as an integrated detector system. 2 Low-mass Detector Systems CPAD, 9-11 January 2013, ANL

3. General Considerations For rather modest efforts at the design and fabrication stages, integrated systems offer substantial paybacks in the material budget without compromises to performance. Having said that, I’ll now concentrate on low-mass materials and applications. 3 Low-mass Detector Systems CPAD, 9-11 January 2013, ANL SiD beam pipe, vertex detector, and tracker: detailed baseline design (Gas cooling) Pixel vertex detector: 0.3% X0 per layer at normal incidence Silicon micro-strip tracker: 1.4% X0 per layer at normal incidence 2-phase or liquid cooling options should be considered if P/A is substantially > 0.05 W/cm 2.

4. Material Impacts Daniela Bartoletto, Steve Nahn, Ron Lipton, Bob Tschirhart, Julia Thom-Levy, and many others have reminded us of material challenges and requirements for future detectors. – My apologies to speakers whose talks I haven’t explicitly mentioned or was unable to attend. Controlling material is critical to physics performance. – That is apparent in vertex detectors and trackers, where multiple scattering limits spatial and momentum resolution, and occupancies and timing requirements impact the overall design. – The production of additional particles increases backgrounds and occupancies and complicates track finding, track tracing, and event reconstruction. – Stability, deflections, and distortions depend on the weight to be supported, the geometry of structures, environmental changes (such as temperature and humidity) from fabrication to operation, and material properties. 4 Low-mass Detector Systems CPAD, 9-11 January 2013, ANL

5. A Sampling of Materials for Low-mass Designs Carbon fiber Carbon derivatives (C-C, Pyrolytic graphite, etc.) Beryllium Titanium alloys Ceramics Advanced compounds (SiC, BN, SiN, diamond, etc.) Conducting polymers and carbon conductors Foams Adhesives Electrical circuit components Liquid / 2-phase cooling tubes 5 Low-mass Detector Systems CPAD, 9-11 January 2013, ANL For a more detailed view of material considerations from a global perspective, please see https://indico.desy.de/conferenceDisplay.py?confId=6112

6. Detector Applications Silicon vertex detectors Gaseous and gaseous/silicon vertex detectors Time projection chambers (TPC’s) Silicon trackers Straw tube trackers Focal plane arrays Space based detectors 6 Low-mass Detector Systems CPAD, 9-11 January 2013, ANL ALICE PANDA ATLAS VTX CMS DES GLAST PLUME Ladder Prototype Note that designs can be deflection limited or strength limited.

7. Silicon/Readout Developments to Reduce the Amount of non-active Material Thin silicon Sensors with low power consumption Sensors with integrated readout Sensor modules and chips with local trigger formation Low mass hybrids and other electrical circuit boards/components Thin flex-cables/circuits Improved power delivery components (e.g. DC-DC converters) 7 Low-mass Detector Systems CPAD, 9-11 January 2013, ANL

8. Approaches to Material Issues Only a set of suggestions! Learn to use existing materials effectively: – Study and choose geometries which optimize structural and thermal performance and stability. – Optimize fabrication parameters of non-isotropic materials, such as carbon fiber. – Take maximum structural/thermal advantage of all materials (including sensors). – Work with industry to reduce/control material production costs. – Conduct vibration/shielding/grounding studies. Develop new or improved materials and fabrication techniques: – Mike Pellin gave a very interesting talk on materials and fabrication techniques under development at ANL. We should seek the benefits of that R&D. – Work with industry on reliable, cost-effective production of foams and other materials with appropriate properties. – Investigate techniques for fabricating and joining materials. Beryllium cones and transition joints Electron beam brazing of larger structures Control of flatness of multi-layer structures (e.g., silicon-foam-silicon) – Investigate adhesives which are re-workable. 8 Low-mass Detector Systems CPAD, 9-11 January 2013, ANL

9. Approaches to Material Issues A database of material properties would be useful in expediting material selection and effective use. – Such databases have been developed by specific projects, such as GLAST and the Fermilab Run II upgrades (probably LHC and other experiments, also), but could be more widely accessible. – We should consider whether NIST, the LBL PDG, or another Lab or institution could provide an easily accessible and up-to-date database for all. Consider a parallel database for documenting design and fabrication techniques. – Analogous to the ASME pressure vessel code, which has separate sections relevant to materials, design, fabrication, and testing – We need to be careful not to preclude improved techniques/wheels. 9 Low-mass Detector Systems CPAD, 9-11 January 2013, ANL

10. Approaches to Material Issues Maintain infrastructure and expertise for fabrication. Maintain/develop infrastructure for physical characterization (test beams, irradiations, materials testing etc.). Maintain/develop facilities with the required metrology tools. Maintain/develop simulation tools (i.e., FEA methods to characterize, describe, and predict the behavior of advanced materials). Seek to establish databases to provide common and consistent input for all projects. 10 Low-mass Detector Systems CPAD, 9-11 January 2013, ANL

11. Specifications We Need from You For experiments relying on accelerator beams: – Radiation length budget as a function of R and Theta – Interaction length budget as a function of R and Theta – Requirements for spatial, momentum, and timing resolutions – Temperature and humidity ranges for assembly and operation – Power dissipation per unit area – Any constraints related to magnetic fields – Limits on short- and long-term changes in 3-D geometry Deflections due to gravity Thermal distortions Distortions related to humidity changes Vibrations – Any limits on deviations from ideal geometry (Is it sufficient to measure/know the geometry or must it be precisely controlled?) – External loads and torques transmitted to the low-mass structure – Radiation dose – Et cetera For other experiments: – Relevant items from above – Other considerations 11 Low-mass Detector Systems CPAD, 9-11 January 2013, ANL In most cases, we have specifications in mind but don’t want to bias your replies.

12. Low-mass Material R&D Plans and Next Steps In addition to specifications, we would appreciate comments on low-mass materials, associated issues, beneficial R&D, and application benefits. We propose to begin generating a table of materials potentially employed in low-mass designs. The table would: – For each of the materials, indicate motivations for its use and issues (if any) – Indicate R&D that could be done to address the issues – Provide a measure of the resources (and time) the R&D would take – Indicate applications, benefits, and synergies – Indicate R&D risks and the potential for high-payback. To get started, we would draft a list of low-mass detector materials, post or distribute it, and ask for feedback to ensure the list is correct and complete. When the list has stabilized, we would seek a “volunteer” with appropriate expertise for each material. The volunteer would provide the input for the table and a few paragraphs for the “white paper”. 12 Low-mass Detector Systems CPAD, 9-11 January 2013, ANL

13. Low-mass Material R&D Plans and Next Steps For the white paper, we suggest summarizing the materials available for low-mass designs and motivations for their use. – Describe promising new materials. – Highlight critical issues and R&D. – If possible, include the full table. – Otherwise, provide a reference to it. What else should be included in the low-mass materials section of the white paper? 13 Low-mass Detector Systems CPAD, 9-11 January 2013, ANL

14. In Summary Please send your comments, specifications, and ideas to us so that a more complete list of material issues and ways to address them can be developed. Please copy Ed Blucher and David Lissauer on email: – blucher@uchicago.edu blucher@uchicago.edu – lissauer@bnl.gov lissauer@bnl.gov 14 Low-mass Detector Systems CPAD, 9-11 January 2013, ANL Carl Haber chhaber@lbl.gov 1-510-486-7050 Bill Cooper cooper@fnal.gov 1-630-840-4093