Update 22 August 2016
Summer Conferences, Magnet Tests and Commissioning
Success at the summer conferences:
MICE presentations at the summer conferences, ICHEP and NuFact, were based around the papers that are in preparation. The bases of the presentations were:
• The first reconstruction of emittance using a beam sampled one particle at a time. These data validate the reconstruction technique we plan to use to study cooling;
• The first measurement of multiple Coulomb scattering (MCS) of muons on lithium-hydride (LiH) using field-off data collected earlier this year; and
• The final results of the optimisation of the cooling-demonstration lattice.
The quality of the presentations was uniformly high. Steve Boyd made the parallel-session presentation at ICHEP, while posters were presented by Victoria Blackmore and Tanaz Mohayai. At NuFact the three parallel-session presenters were Francois Drielsma, Ryan Bayes and Yordan Karadzhov. Each of the presenters gave a very professional impression, reflecting well on the months of hard-work that led to the excellent new results.
Successful combined test of SSU and focus coil:
On the 02Sep16 the magnet-string commissioning passed a most significant milestone. The combination SSU was run in combination with the FC at currents representative of those that are required to deliver the solenoid-mode scattering programme. The field in the tracking volume was 3T, the operating point chosen for the Step IV programme.
SSU was run up so that the ECE combination carried 206A, M2 190A and M1 100A. Then, the FC was run to 75A in small current steps. The attached plot shows the ramp of the FC with SSU energised. The blue trace is the FC current, the black trace is the force measured by the load cells on the FC and the magenta trace is the inter-module force calculated using the currents in the various windings and the coil dimensions. This success will allow the magnet and operations teams to plan the preparation for the User Cycle with confidence.
Magnet-string commissioning will continue next week and on to the start of the next ISIS User Cycle on 13Sep16.
Data in the bank:
A substantial quantity of high-quality data with the superconducting-magnet channel in various configurations was taken in the most recent ISIS User Cycle. This data can be used to study the alignment of the magnetic axis of each magnet individually and to make initial studies of the solenoid-mode optics. It is important that these studies are documented and published the results for future reference.
Commissioning and Hall status update:
Progress has been made in identifying issues in the modules that control the “trim current” to the end coils in the solenoids. A test remains to be performed to demonstrate the stability of the end coils in operation. The source of transients observed in the voltage-tap signals of SSU and SSD remains to be understood fully. In the last User Cycle, stable operation of SSU and SSD was achieved with a voltage-tap threshold of 200mV. A control-software update for the spectrometer solenoids has been prepared at Fermilab and will be deployed next week. Further tests to elucidate the source of the transient signals will then be performed.
There has been steady progress on the preparation of the liquid-hydrogen vessel in R9. The absorber bodies have been passed "good to go" and the MLI has been fitted. Pipe-work modifications are complete. Final level-sensor checks have been carried out and tape to reduce the emissivity of the warm surfaces of the magnet have been installed. The end-caps have been mounted on cradles to allow final preparations to be made. The end caps will be fitted towards the end of next week. Evacuation of the module and the "interspace" can then begin.
The upgrade to the Hall water system is now complete; the demineralised and “inhibited” circuits are now separate; the final modifications having been made on Thursday 01sep16.
The Kaiser compressor serving the Linde refrigerator that cools the decay solenoid was serviced. Following the service, air contamination of the helium was observed and a number of small leaks were found. Kaiser engineers made a visit to the Hall on 31Aug16 and identified two leaks. Work continues to establish that the system is leak tight and, if it is not, to address the remaining issues.
The remedial work on the air-conditioning units is complete. The Hall now has five functioning air conditioners. This, together with the decreasing air temperatures as autumn comes to Oxfordshire, is estimated to be sufficient to stabilise the ambient temperature in the Hall.
ISIS User Cycle 2016/03 (13Sep16 — 29Oct16):
Planning for the next User Cycle is now well underway. The run plan includes data-taking to allow detailed studies of the optics of the Step IV solenoid-mode lattice. The priority for the Cycle is empty-absorber data-taking for the Step IV, field-on scattering programme.
Shift sign-up in CHEESE is live and all are encouraged to sign up.