The Linac4 RFQ will accelerate the H beam from the ion source to the energy of 3 MeV. The RFQ is composed of three sections of one meter each, assembled by means of ultra high vacuum flanges and adjustable centring rings. The complete 3-m long RFQ will be supported isostatically over 3 points like a simple beam in order to minimise the maximum deflection. The ridge line, used to feed the RF power into the RFQ, will be supported via springs and its position adjusted in such way that no strain is introduced into the RFQ at the moment of its connection. The mechanical design has been done at CERN where the modules are completely manufactured, heat treated and brazed also. In that way, all of the processes are carefully controlled and the influence, notably of the heat treatments, has been understood in a better way. Since 2002 several four vanes RFQ modules have been brazed at CERN for the TRASCO and IPHI projects. A two-step brazing procedure has been tested. This technique is actually used for the assembly of the CERN Linac4 RFQ. This paper describes the design, the mechanical procedures adopted for machining and assembly and the first results obtained.

The design of the Drift Tube Linac (DTL) for the new linear accelerator Linac4 at CERN has been made ready for production: H - -ion beams of up to 40 mA average pulse current are to be accelerated from 3 to 50 MeV by three RF cavities operating at 352.2 MHz and at duty cycles of up to 10%. In order to provide a margin for longitudinal matching from the chopper line, the longitudinal acceptance has been increased. The synchronous phase starts at -35 deg in Tank1 and ramps linearly to -24 deg over the tank while it went from -30 to -20 deg in the previous design. The accelerating gradient has been reduced to 3.1 MV/m in Tank1 and increased to 3.3 MV/m in Tank2 and Tank3 for a better distribution of RF power between tanks that is compatible with a mechanical design. To make the transverse acceptance less sensitive to alignment and gradient errors, the focusing scheme is now FFDD over all 3 tanks. Design features that were demonstrated in earlier reports have been improved for series production. Results of high power RF tests of the DTL prototype equipped with permanent magnet quadrupoles (PMQs) are reported that test the voltage holding in the first gaps in presence of magnetic fields.

The Linac4 RFQ will accelerate the H- beam from the ion source to the energy of 3 MeV. The RFQ is composed of three sections of one meter each, assembled by means of ultra high vacuum flanges and adjustable centring rings. The complete 3-m long RFQ will be supported isostatically over 3 points like a simple beam in order to minimise the maximum deflection. The ridge line, used to feed the RF power into the RFQ, will be supported via springs and its position adjusted in such way that no strain is introduced into the RFQ at the moment of its connection. The mechanical design has been done at CERN where the modules are completely manufactured, heat treated and brazed also. In that way, all of the processes are carefully controlled and the influence, notably of the heat treatments, has been understood in a better way. Since 2002 several four vanes RFQ modules have been brazed at CERN for the TRASCO and IPHI projects. A two-step brazing procedure has been tested. This technique is actually used for the assembly of the CERN Linac4 RFQ. This paper describes the design, the mechanical procedures adopted for machining and assembly and the first results obtained.

The PIMS (Pi-Mode-Structure) cavities for Linac4 are made of 7 coupled cells operating in π-mode at a frequency of 352 MHz. The mechanical concept is derived from the 5-cell cavities used in the LEP machine, whereas cell length and coupling are adapted for proton acceleration in the range from 50 to 160 MeV. Linac4 will be the first machine to employ this type of cavities for low-beta protons. During the first years of operation the PIMS will be used at low duty cycle (0.1%) as part of the consolidated LHC proton injector complex. It is designed, however, to operate eventually in a high duty cycle (10%) proton injector, which could be used as proton front-end for neutrino or RIB applications. To prepare for the series construction of the 12 PIMS units the first cavity (102 MeV beam energy) has been designed and constructed at CERN, to be used as a hot prototype for RF tests and as a pre-series mechanical unit. In this paper we report on some of the design features, the construction experience, and first measurements.

The construction of Linac4, the new 160 MeV CERN H injector, has started with the goal of improving the LHC injection chain from 2015 with a new higher energy linac. The low energy front end of Linac4 is based on a 352 MHz, 3-m long Radiofrequency Quadrupole (RFQ) accelerator [1]. The RFQ accelerates the 70 mA, 45 keV H - beam from the RF source to the energy of 3 MeV. The fabrication of the RFQ has started at CERN in 2009 and is presently in progress, aiming at the completion of the full structure by early 2011. The RFQ consists of three modules, one meter each; the fabrication alternates machining phases and stress relief cycles, for copper stabilization. Two brazing steps are required: one to assemble the four parts composing a module, and a second one to install the stainless steel flanges. In order to monitor that the tight mechanical and alignment budget is not exceeded, metrology measurements at the CERN workshop and RF bead-pull measurements are performed during the fabrication process. In this paper we report results obtained during the machining and the assembly of the first module of the Linac4 RFQ and data produced by RF measurements performed during its fabrication.

To produce dense pbar beams at very low energies (100-200 keV), a small decelerator ring could be built and installed between the existing AD ring and the experimental area. Phase-space blowup during deceleration would be compensated by electron cooling in order to obtain final emittances comparable to the 5MeV beam presently delivered by the AD. This report describes preliminary machine parameters and layout of ELENA and also gives an approximate estimate of cost and manpower needs.

The high-energy section of Linac4, between 100 and 160 MeV, will be made of a sequence of 12 seven-cell accelerating cavities of the Pi-Mode Structure (PIMS) type, resonating at 352 MHz. The cell length is the same within a cavity, but changes from cavity to cavity according to the beam velocity profile. Compared to other structures used in this energy range, π-mode cavities with a low number of cells have the advantage of simplified construction and tuning, compensating for the fact that the shunt impedance is about 10% lower because of the lower frequency. Field stability in steady state and in presence of transients is assured by the low number of cells and by the relatively high coupling factor of 5%. Standardising the linac RF system to a single frequency is considered as an additional economical and operational advantage. The mechanical design of the PIMS will be very similar to that of the 352 MHz normal conducting 5-cell LEP (Large Electron Proton collider at CERN) accelerating cavities, which have been successfully operated at CERN for 15 years. After reviewing the basic design principles, the paper will focus on the tuning strategy, on the field stability calculations and on the mechanical design. It will also report the results of measurement on a cold model and the design of a full-scale prototype.

A measurement of the neutron induced fission cross sections of Np, Am and of Cm is proposed for the n_TOF neutron beam. Two sets of fission detectors will be used: one based on PPAC counters and another based on a fast ionization chamber (FIC). A total of 5×10 protons are requested for the entire fission measurement campaign.

608 Reactivation of polyoma virus infection (PVI) is associated with immunosuppressive states such as the use of antirejection therapy in organ transplantation. Although PVI in renal transplant patients is usually asymptomatic, pathological associations such as ureter stenosis and viral cytopathic changes in urine and kidney with and without concurrent rejection have been described (Pappo et al. Modern Pathology 1996;9:105). All these could potentially affect long term graft survival. Renal biopsies and urine cytology from 3 patients with acute rise in creatinine (1.8 to 4.2,1.2 to 2.2 and 1.8 to 2.2) at 5, 14 and 30 months post-renal transplant respectively, were studied by light and electron microscopy and immunohistologically (antibody against simian virus SV40). The renal biopsies showed sparse lymphocytic inflammation with no significant tubulitis. The renal tubules displayed marked tubular injury consisting of cellular enlargement, nuclear changes (hyperchromasia, karyomegaly and pale granular basophilic inclusions), flattened epithelial lining, basement membrane denudement, marked cell blebbing and drop-out(apoptosis). Cellular and protein casts containing debris with similar cytopathic changes as in the lining cells were prominent. Urine samples showed abundant virally infected (BK) cells as well as degenerative changes in tubular epithelial cells, including numerous apoptotic bodies. Electron microscopy and immunostains confirmed the presence of viral inclusions consistent with PVI. Two to 4 months after the diagnosis creatinine had risen to 7.4, 2.3 and 2.9 respectively; subsequent biopsies failed to show acute allograft rejection. There was no evidence of ureteric stenosis on imaging studies. The patients were maintained in therapeutic levels of immunosuppressive drugs. We conclude that PVI may be etiologically associated with significant acute allograft dysfunction and may be related to long-term impairment of graft function. Although reportedly, differentiation of acute rejection from PVI-related interstitial nephritis may be difficult morphologically, this did not apply in these 3 cases. The degenerative/regenerative tubular findings indicating cytopathic tubular damage and necrosis were strikingly different from the changes seen in typical acute rejection. Evaluation for PVI in biopsies and urinary cytology appear highly indicated in cases of unexplained allograft dysfunction.

An expandable RFQ has been designed and built. Its length can be modified in steps to match the different phases of the Laser Ion Source (LIS) study. This paper describes the basic design approach, the field simulations using MAFIA, the establishment of a lumped-element equivalent circuit using PSPICE, model measurements, RF cold measurements and the strategy to trim longitudinal field flatness. Results of RF power tests are also given.

The PS Multi-Turn Extraction Study Group M. J. Barnes*, O. E. Berrig, A. Beuret, J. Borburgh, P. Bourquin, R. Brown, J.-P. Burnet, F. Caspers, J.-M. Cravero, T. Dobers, T. Fowler, S. Gilardoni, M. Giovannozzi (Study Group Leader), M. Hourican, W. Kalbreier, T. Kroyer, F. di Maio, M. Martini, V. Mertens, E. Métral, K.-D. Metzmacher, C. Rossi, J.-P. Royer, L. Sermeus, R. Steerenberg, G. Villiger, T. Zickler

The implementation of the new Multi-Turn Extraction (MTE) at the CERN Proton Synchrotron required major hardware changes for the nearly 50-year old accelerator. The installation of new Pulse Forming Networks (PFN) and refurbished kicker magnets for the extraction, new sextupole and octupole magnets, new power converters, together with an in-depth review of the machine aperture leading to the design of new vacuum chambers was required. As a result, a heavy programme of interventions had to be scheduled during the winter shut-down 2007-8. The newly installed hardware and its commissioning is presented and discussed in details.

The Drift Tube Linac (DTL) for the new linear accelera- tor Linac4 at CERN will accelerate H--ion beams of up to 40 mA average pulse current from 3 to 50 MeV. It is de- signed to operate at 352.2 MHz and at duty cycles of up to 10 %, if required by future physics programmes. The accelerating field is 3.2 MV/m over the entire length. Per- manent magnet quadrupoles (PMQs) are used as focusing elements. The 3 DTL cavities consist of 2, 4 and 4 sec- tion of about 1.8 m each, are equipped with 35, 41 and 29 drift tubes respectively, and are stabilized with post- couplers. Several new features have been incorporated in the basic design. The electro-magnetic design has been re- fined in order to reduce peak field levels in critical areas. The mechanical design aims at reducing the complexity of the mechanical structure and of the adjustment procedure. Drift tubes and holders on the tanks that are machined to tight tolerances do not require adjustment mechanisms like screws or bellows for drift tube positioning. A scaled cold model, an assembly model and a full-scale prototype of the first half section have been constructed to validate the de- sign principles. The results of metrological and RF tests are presented.

Due to the high transmission of thermal neutrons through uranium, plutonium and thorium, non-irradiated nuclear fuel can easily be inspected concerning defects, homogeneity and enrichment. Especially when so-called "burnable poisons" are added to the pellets (used for the prolongation of the fuel cycles in NPP's), the non-destructive manufactory control can best be done with neutron transmission analysis, qualitatively and even quantitatively with high precision. The advanced core design of the Swiss nuclear power plants (NPP) takes profit from diverse fuel enrichment and so- called poisoned fuel material in order to achieve uniform power distribution across the core over the full fuel cycle. The zero-power research reactor PROTEUS has launched a program of investigations for the verification of the intended power distribution using original NPP fuel elements and some specially manufactured fuel pellets (1). Another important question is the effect of burn-up of nuclides to the limit of criticality over the full operation cycle. Special pellets were manufactured with "symbolic" fission products included. All calculations and the comparison to and verification of experimental data are presently based on the values about enrichment and poisoning given by the manufacturers. The method of neutron imaging provides a powerful and non-destructive tool for the determination of the enrichment in the isotope U-235 and the homogeneity in distribution of additives (neutron absorbers like Gd, Sm, Dy, B, Rh, Cs and Nm).

The manufacturing of the Linac4 Drift Tube Linac (DTL) components has been completed and the assembly of the structures is in its final stages. 3 tanks of 3.9m, 7.3m, and 7.3m, designed to accelerate a 40mA average pulse current H–beam from 3 to 50MeV, are being assembled from 2, 4 and 4 segments of about 2.0m length, containing each from 22 drift tubes at the low energy end, down to only 6 at the high energy end. Due to its peculiar design avoiding adjustment mechanisms on the drift tube, tight tolerances have to be maintained in the production. This paper discusses the assembly stages that are used to achieve the tolerances over the full length of the structures. Metrology results on the assembled DTL Tank1 confirm the required precision.