Statement in summary of VELO construction at time of EDR Author: T.J.V.Bowcock At the time of the EDR (21 April 2005) the VELO module construction is delayed relative to the expected state in January 2005, as communicated to the LHCC. We estimate this delay is approximately 2 months. The single largest contributor to the delay was the discovery that an additional batch of K-04 hybrids ordered for pre-production modules were heavily warped compared with earlier prototypes. There are two possible causes: the use of thicker kapton layers by the manufacturer (the thinner layers are no longer available in the UK) and changes to the production methodology. New processing should reveal within 1-2 weeks whether this problem/risk may be “retired”. We note that this risk was so entirely unexpected it did not form part of the “risk register” maintained as part of our project monitoring tool. The problems facing transition to the production faced are summarized in another document for the EDR. The problems that remain that present a serious risk to the experiment 1. Low yield of pitch adaptors 2. Warping of hybrids (discussed above) We expect a new batch of PA’s within the next few days. If the remaining problems are overcome and the module losses incurred during module production are kept to less than about 5% we remain confident (see the EDR Gantt) the 40 assemblies may be delivered to CERN in early 2006 and of order 10-15 spare assemblies delivered by May 2006. No complete “physics level” assemblies are expected to be delivered until at least September 2005 although K-04 versions will start being constructed on receipt of the new batch of K-04’s. The group remains committed to delivering all assemblies before April ’06 in time for the testbeam at CERN. Should the yield of assemblies drop to a (pessimistic) 60%, we expect the final modules to be delivered in May 2006. In this scenario there will be no spares. This will be dominated by loss of sensors and the cost of the hybrids. We note a completed assembly costs approx 40kCHF (capital) and spares are very expensive to manufacture. The project is proceeding, even given the problems described above, within 1% of its original spend profile.