22223370
Testing, Installation, Commissioning and First Operation of the ISIS RFQ Pre-Injector Upgrade
Situated at the Rutherford Appleton Laboratory (Oxon., UK), ISIS is currently the world's most intense pulse spallation neutron source, delivering 160 kW of 800 MeV protons to a tungsten target at 50 Hz. A major facility upgrade programme involves the construction of a second, 10 Hz target and an increase in the total beam power of up to 50% (i.e. up to 240 kW). To achieve the planned increase in average beam current to 300 μA whilst maintaining the current manageable levels of beam loss, four 2nd harmonic RF cavities have been installed in the synchrotron and the ageing Cockcroft-Walton preinjector in the linac has been replaced with a 665 keV, 202.5 MHz, 4-rod Radio Frequency Quadrupole (RFQ). This paper describes the extensive testing, installation, commissioning and successful initial operation of the RFQ pre-injector upgrade.
121053847
Electromagnetic modeling of the extraction region of the ISIS H− ion source
The ISIS Penning surface plasma source, which routinely produces 35 mA of H− ions during a 200 μs pulse at 50 Hz for uninterrupted periods of up to 50 days, is regarded as one of the leading operational sources in the world. The ISIS source should provide an excellent starting point for a development program to produce H− ion sources with performances exceeding those achieved today, which will be a key requirement for the next generation of high power proton accelerators. One goal is to produce 60 mA of H− ions from the source without large departures from the optimum conditions for source lifetime or increased emittance. As the ISIS source operates in the space-charge limited mode it is predicted that an increase in extraction potential from 17 to 25 kV should be sufficient to achieve this, and a suitable pulsed power supply for the ion source extraction electrode has been manufactured. An understanding of how extract geometry changes affect beam transport is essential for operation at higher extraction ...
59362451
THE RFQ TEST STAND ION SOURCE AT RAL
The RFQ test stand at Rutherford Appleton Laboratory (RAL) is now being operated with an ion source identical to that used on ISIS. This is a surface plasma ion source of the Penning type, and on ISIS routinely produces 35 mA of H − ions during a 200 µs pulse at 50 Hz for uninterrupted periods of up to 50 days. A new ion source vacuum chamber which is compatible with the low energy beam transport system for the RFQ has been constructed, and the layout of power supplies and other essential services have been reconfigured in order to ensure that the RFQ will fit the space available when it is eventually installed on ISIS. An extensive redesign of many power supplies, where exact duplication of the ISIS equipment has proved impossible because of component obsolescence, has been necessary. In addition a new timing system and control systems using fibre optic ethernet have been developed specifically for this application.
13721950
Handling of the generation of primary events in Gauss, the LHCb simulation framework
The LHCb simulation application. Gauss, consists or two independent phases, the generation of the primary event and the tracking of particles produced in the experimental setup. For the LHCh experimental program it is particularly important to model IS meson decays: the KvtGcn code developed in CLEO and BaBah has been chosen and customized for non-coherent B production as necuring in pp collisions at the LHC, The initial proton-proto n collision is provided by a different generator engine, currently PYTHIA 6 for massive prwluclion of signal and generic pp collisions events. Beam gas events, background events originating from proton halo, cosmics and calibration events for different detectors can be generated in addition to pp collisions. Different generator packages as available in the physics community or specifically developed in LHCb are used for the different purposes. Running conditions affecting the events generated such as the size of the luminous region, the number of collisions occuring in a bunch crossing and the number of spill-over events from neighbouring bunches are modeled via dedicated algorithms appropriately configured. The design of the generator phase of Gauss will be described: a modular structure with well defined interfaces specific to the various tasks, e.g. pp collisions, particles' decays, selections, etc. has been chosen. Different implementations are available for the various tasks allowing selecting and combining them as most appropriate at run time as in the case of Pythia 6 im pp collisions or HIJING for beam gas. The advantages of such structure, allowing for example to adopt transparently new generators packages will be discussed.
125258275
Measuring g with B meson decays to charmed final states at LHCb
1525627
Advanced multi-beam spectrometer for the Green Bank Telescope
A new spectrometer for the Green Bank Telescope (GBT) is being built jointly by the NRAO and the CASPER, University of California, Berkeley. The spectrometer uses 8 bit ADCs and will be capable of processing up to 1.25 GHz bandwidth from 8 dual polarized beams. This mode will be used to process data from focal plane arrays. The spectrometer supports observing mode with 8 tunable digital sub-bands within the 1.25 GHz bandwidth. The spectrometer can also be configured to process a bandwidth of up to 10 GHz with 64 tunable sub-bands from a dual polarized beam. The vastly enhanced backend capabilities will support several new science projects with the GBT.
119772699
Handling of the generation of primary events in Gauss, the LHCb simulation framework
The LHCb simulation application, Gauss, consists of two independent phases, the generation of the primary event and the tracking of particles produced in the experimental setup. For the LHCb experimental program it is particularly important to model B meson decays: the EvtGen code developed in CLEO and BABAR has been chosen and customized for non-coherent B production as occuring in pp collisions at the LHC. The initial proton-proton collision is provided by a different generator engine, currently PYTHIA 6 for massive production of signal and generic pp collisions events. Beam gas events, background events originating from proton halo, cosmics and calibration events for different detectors can be generated in addition to pp collisions. Different generator packages as available in the physics community or specifically developed in LHCb are used for the different purposes. Running conditions affecting the generated events such as the size of the luminous region, the number of collisions occuring in a bunch crossing and the number of spill-over events from neighbouring bunches are modeled via dedicated algorithms appropriately configured. The design of the generator phase of Gauss will be described: a modular structure with well defined interfaces specific to the various tasks, e.g. pp collisions, particle decays, selections, etc. has been chosen. Different implementations are available for the various tasks allowing selecting and combining them as most appropriate at run time as in the case of PYTHIA 6 for pp collisions or HIJING for beam gas. The advantages of such structure, allowing for example to adopt transparently new generators packages, will be discussed.
120459648
Studies of hadronic B decays to ﬁnal states containing open charm mesons at LHCb
The latest results from the programme of studies of beauty hadron decays into final states with open charm at the LHCb experiment are presented. These decays provide several complementary measurements of CP violation and parameters of the CKM matrix. The results in this report include first observations as well as some world leading measurements.