TIB/TID assembly and integration plans

1. TIB/TID assembly and integration plans The set of tests planned on the mechanical assembly of the TIB/TID substructures, subsequently on the electrical fixtures and on the optical hybrids and finally on the modules both during and after installation are described. The purpose of these sets of tests is to validate the continued functionality of all installed components before proceeding to further installations.

2. The philosophy behind the tests • All components, be they cooling pipes, mother cables or modules, are thoroughly tested before being shipped to the TIB/TID assembly site. Nevertheless, any failures (devices damaged during transportation or installation; devices damaged in the installation of other devices) must be detected at the earliest time possible, because of the complexity of replacing anything in the Inner Tracker after further components have been put in place. • Also, it is important to spot at the very onset any systematic problem, which may hint to a yet to be perfected procedure in the installation mechanism. Thus the choice to run tests practically after the insertion of each device, at least for the initial stages of the TIB/TID assembly. • Only experience and accumulated statistics will show which tests are mandatory, which are significant and which can (or must) be skipped. Piero Giorgio Verdini, INFN Pisa (TIB/TID)

3. Tests on the bare mechanics • Validation of the carbon fiber structure, checking that its geometry falls within tolerances in all its parts: the program for the DEA Coordinate Measurement Machine (CMM) in Pisa is ready and has already been used on similar structures. The test aims to ensure the compatibility of the structure geometry with the installation of modules and with the assembly of the TIB/TID as a whole. • Verification of the coplanarity of the four fixation points that define the module position. This is important to ensure that the thermal contact of the modules with the cooling fixtures will be adequate, and that the modules themselves will not be subject to torque forces. • Any other test felt needed to ensure that the mechanical structure will remain true and sound during operation. This includes repeated cooling and warming cycles followed by CMM measurements on the structure, looking for permanent deformations. Piero Giorgio Verdini, INFN Pisa (TIB/TID)

4. Tests on the cooling pipe assembly • Measurement of the ratio between the flow and the pressure drop for each manifold. The rationale behind this test is to ascertain whether, during transportation, insertion and gluing, the (rather thin) pipes have suffered any narrowings or blocks. Note that individual pipes initially, and later assembled manifolds, must pass a similar acceptance test. • Verification that a very fast rise in coolant pressure (from zero to twice the nominal operating values) does not harm the pipes. Here, the rationale is to check that during transportation, insertion and gluing the pipes and the solder joints have not developed any weak spots. Again, pipes and manifolds pass a similar acceptance test earlier on. • Measurement of the thermal impedance between the module ledges and the cooling pipes, using dummy modules with resistive loads to dissipate variable amounts of power. The rationale is to ensure that the thermal contact is compatible with the requirements. Piero Giorgio Verdini, INFN Pisa (TIB/TID)

5. Tests on mothercables and CCU modules Following the insertion of the (pre-tested) mothercables and of the (also pre-tested) CCU carriers, including the Digital Optical Hybrids (DOH), comes a series of electrical tests. • Power-up of the DOH and CCU modules, checking that the current absorption is compatible with the expected values. • Readout of the Control Ring configuration, ensuring that the ring is working and that all and only the expected CCU chips are present. The software needed for this test has already been developed some time ago by the Mulhouse and Strasbourg groups, and has been validated throughout a number of beam tests: it can not only identify a defective CCU in the ring, but also reconfigure the ring for operation without it. Power-up of the module LV and HV power supplies, ensuring that no short circuits have been introduced during the installation procedure. Piero Giorgio Verdini, INFN Pisa (TIB/TID)

6. Grounding and environmental sensors After the installation of the mothercables and of the CCU modules, it becomes possible to verify the ground interconnections and to wire the environmental sensors (two Pt1000 thermometers plus one HMX relative humidity meter through each CCU power cable) and to test the results. • Test the DC electrical continuity between the common ground points. The acceptance criterion will presumably be compatibility with an upper limit. • Test the physical integrity of the environmental sensors (resistance of the Pt1000 thermometers; resistance of the four “arms” of the strain gauge for the HMX RH meter). The aim is to verify that the sensors have not suffered mechanical damage during installation. • Read the environmental sensors through the CCU power cable and verify that the measured values for the temperature and the relative humidity are compatible with the surrounding environment. This test ensures that not only the sensors are healthy, but also that the connections are correct. Piero Giorgio Verdini, INFN Pisa (TIB/TID)

7. Power Supplies: requirements • The early electrical tests already put some requirements on the power supplies to be used: they (the PS) must be capable of measuring with some accuracy the currents drawn, and they certainly must have a shutdown system in case of overcurrents in order to protect the hardware in case of erroneous connections. The current limit should be relatively easy to reconfigure, to prevent significant delays when moving from one test to another. • In view also of avoiding the unnecessary duplication of the software development effort, it is preferable that prototypes of the “final” power supply system be available and used for the assembly tests. While the prototypes should be already well debugged, it is not unconceivable that this operation might point out existing weak points in time for finding and implementing a solution before installation in Point 5. Piero Giorgio Verdini, INFN Pisa (TIB/TID)

8. Analogue optical hybrids and fibers (1) • Following the installation of each and every analogue optical hybrid (AOH) and with the help of a passive pseudo-module (needed to close the lines of the I2C bus from the mothercable onto the optical hybrid) comes a second sequence of electrical tests. • Power-up of the module LV supplies, checking that the current absorption is compatible with the expectations . • Read/Write test of the I2C registers on the AOH, to ensure that no damage occurred during transportation and installation. • Measurement of the output light levels, in DC, for different settings of the AOH laser drivers. The rationale is to verify that the optical fibers and the optical couplings between them and the lasers have not been damaged during transportation and installation. Piero Giorgio Verdini, INFN Pisa (TIB/TID)

9. Analogue optical hybrids and fibers (2) • After the installation of all the optical hybrids in a string or a ring, and before any modules are installed, is the last time when it is reasonably easy to replace a failed AOH. Thus a final validation via another set of tests, similar to the previous. This final test might replace the AOH-by-AOH sequence if experience shows it to suffice. • Read/Write test of the I2C registers on every AOH, to ensure that no damage occurred during the installation of the other devices in the string/ring. • Simultaneous measurement of the output light levels, in DC, for different settings of the AOH laser drivers. The rationale is to verify that the optical fibers and the optical couplings between them and the lasers have not been damaged during the installation of the other devices in the string/ring. Piero Giorgio Verdini, INFN Pisa (TIB/TID)

10. Detector modules (1) • Following the insertion of each and every detector module comes a new sequence of tests. From this point onward, the requirements on the Power Supply system become very close to the final ones. • Power-up of the Low Voltage supplies, measuring the currents. The purpose is to verify that the power consumption falls within the expected values. Of course, the power supply must be capable of supplying enough LV power for all modules installed and also of monitoring the currents with sufficient precision. • Read/Write test of the I2C registers on the module and AOH pair. The rationale behind this test is to ensure that no damage occurred to the module during transportation and installation, nor to the AOH during the module installation. This type of software too has already been developed and debugged during a number of tests on the X5 beam line. Piero Giorgio Verdini, INFN Pisa (TIB/TID)

11. Detector modules (2) • Test the correct connection of the Bias kapton. This is a delicate exercise, since polarizing the sensors, and maybe measuring their I-V characteristic under daylight is not the best possible idea. It would be extremely time-consuming, and quite dangerous, to shade the structure with an opaque cover avery time a module is inserted. It is not obvious that it will be possible to guarantee that the temperature and the relative humidity will be kept within the limits accepted for the equivalent sensor test. Lastly, a good module may draw currents below the detection capabilities of the HV power supply when unirradiated. • A solution based on a Low Frequency (<8 kHz) measurement of the sensor capacitance is currently under study. Should this method be applicable, the presence of the sensor at the far side of the bias lines should be rather easy to infer. If, for whichever reason, the proposed method is not suitable, then another safe alternative must be studied. • As a last resort, measuring the resistance of the backside thermistor will provide a hint that, at least, the connector is in place. Piero Giorgio Verdini, INFN Pisa (TIB/TID)

12. Further tests in the cold chamber • A list of tests meant to verify the integrity and operability of the fully loaded TIB/TID substurctures has already been circulated quite some time ago. At this stage, the only further statement that I am prepared to make is that, in order to test the full subassemblies in an environmentally controlled chamber, it is necessary to use the 9U FED prototypes, the 9U FEC prototypes and the “final” Power Supply prototypes. Piero Giorgio Verdini, INFN Pisa (TIB/TID)

13. Special tooling needed • In order to prevent the occurrence, or at least to minimize the possibility of mechanical damage to the already installed components during the insertion of new ones, specific tools are currently under study for the TIB/TID. These include, but are not limited to: • insertion rails to drive the movement of modules onto the mechanical structure; • a number of special hand tools for the insertion and extraction of the (small and delicate) connectors; • protective (transparent) covers; • cable and fiber supports. • In addition, storage and transportation containers for the TIB/TID subassemblies must be designed and produced. Piero Giorgio Verdini, INFN Pisa (TIB/TID)

14. Manpower requirements • I expect that a crew of two not necessarily qualified operators will be sufficient for everyday work at each of the three assembly tables under the assumption that at least one specialist will be available at all times in case of problems. • For the installation in the cold room of each subassembly, and the connection to the necessary services, a crew of two operators and one expert is probably enough. However, depending on how many service channels will be available, this crew might be needed over a longer period than just the initial installation time (if cooling pipes must be reconnected after testing a subset of the structure, power cables rerouted and so on, this crew becomes a permanent workforce rather than an occasional one). • The tests on subassemblies installed in the cold room probably only require one operator plus one expert on call. However, depending on what discussed above, the entire installation crew might be attached to the task. Piero Giorgio Verdini, INFN Pisa (TIB/TID)