Blog detailing the turning on TS2
19 September 2008 16:30
Last night, another milestone was achieved at ISIS when both neutron targets were operated at full power for the first time.
From 2215 on 18 September 2008, a 10 Hz beam was sustained onto the second target station for over 5 hours delivering 36 micro-amp proton beam current. At the same time 40 Hz beam was delivered to Target Station 1.
This historic moment represents the start of regular two target operations at ISIS. It was also the first time that solid methane moderators have been operated with such a high beam power anywhere in the world.
The sustained running allowed the target and moderator teams to confirm that the target station performance was in agreement with technical calculations. In addition, three anneals of the moderators were carried out to relieve radiation damage in the solid methane. Each took around 15 minutes to complete. Annealing the moderators regularly will be part of the normal operation of the second target station.
Two target running resumed this afternoon, to begin commissioning the Inter instrument for full-time operation.
An air of contentment and exhaustion has settled over ISIS. Everywhere is strangely silent save for the humming of pumps and ventilation. Machine physics has been completed for this evening, and the accelerator is being set-up to just send beam to target 1. Tomorrow morning accelerator physics teams will spend some hours working on the second harmonic systems that will trap more beam current in the synchrotron to give the required beam currents for two target operations.
With the target two cryogenic systems still operating, the next couple of days will be usefully used to carry out tests and experiments with the new moderators, to gain experience in controlling their responses.
TS-2 First Neutrons Inter Monitor Spectrum Sunday 3rd August 2008
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After further beamline checks, and some waiting for the accelerator, this is the first data to be published from the Inter instrument. Data fitting indicates that the intensities agree with calculations and that the distribution is consistent with the moderator temperature.
The first neutrons meet all of our technical performance predictions and creating them is a significant milestone in the life of the facility and in the completion of the project. Building on the success and expertise we have developed over the past 20 years at ISIS, the second target project will allow us to move further into the areas of soft matter, advanced materials and bioscience, carrying out fundamental research that will shape the technological advances of tomorrow.”
After several hours work this morning scanning the shutter, the beamline suddenly came into alignment at 13:08 and neutrons were measured. So many neutrons flooded down the beamline that the gas tube detector (which had been temporarily removed from its shielding housing and taped to the sample table) went off scale. There are a lot of very relieved and jubilant people in the Inter control room (many who slept fitfully during the night wondering how to get the instrument working). More data is being collected in order to analyse the neutron spectrum and compare to calculations.
The accelerator has been sending low repetition rate beams to both target stations for much of the day. With two targets operating, one proton bunch is diverted and sent to the second target station and the next four bunches whizz off to target one. Radiation surveys while beam is being sent to target two have measured no radiation outside the shielded areas.
Beam extraction into the second target beamline is very clean, with very little beam loss being registered. Poor beam extraction to the second target was one of the greatest worries for the accelerator team. Elsewhere along the beamline, beam losses are quite low, but still not acceptable to run higher beam current for now.
The target and moderators are working well, but the teams would like to have normal beam intensity to check performance fully. Both moderators are filled with solid methane and operating at around 30K.
Meanwhile, in R3 where a temporary control area for the Inter instrument has been set-up, it has been a long and frustrating day trying to measure neutrons in the Inter beamline. With such low numbers of proton bunches onto the target, often with long pauses between, it is proving to be quite hard to interpret the very small amount of data collected so far. Numerous checks on beamline alignment and equipment performance are continuing.
The first six proton bunches were sent slamming down the extracted proton beamline into the new tungsten target at 16:24 this afternoon.
Excellent news and a great achievement to get to this stage!
The coupled methane moderator has cooled down below 70 K and is filled with solid methane.
Beam down the proton beamline now has to be aligned to reduce beam loss.
Radiation surveys with the experimental hall building R80 must also be done.
Low repetition beam is being sent to target 1 allowing the accelerators to be fine-tuned. This work will continue through the morning.
Overnight, live testing of the personnel interlocks was completed and accepted. Testing personnel interlocks is a time consuming and tedious task, since the test teams have to systematically defeat a system that really wants a fight. Apparently, not a particularly wonderful experience. Target cooling water flow and temperature trip checks were also successful.
Setting up the proton beamline to deliver first beam down to target station 2 will hopefully start this afternoon. Initially small numbers of proton bunches will be sent, with health physics teams carrying out surveys within the second target experimental hall to check shielding integrity.
With the current timetable, we might expect to open the beam line shutter to the Inter instrument sometime tomorrow.
The 4616 valve in the linear accelerator has been changed and is conditioning to RF power. To allow the valve to settle in, it has been decided not to run the accelerators overnight.
A number of live checks are being made now and tonight on the personnel interlock system to confirm that the accelerator switches off correctly in emergency situations. When these are complete the accelerator will be readied to run beam when needed.
The cryogenic system in the target station has passed its room temperature leak and pressure tests. The cryogenic system is an intricate network of large and complex components (cold boxes, buffer tanks, compressors, transfer lines, valve panels, moderators) all joined together with over 2 kilometres of pipes. When operating it supplies liquid helium, methane and hydrogen to the neutron moderators that surround the tungsten target
The current plan is to start cooling the cryogenic system from 0500 Friday morning.
This morning has been set-aside for various tests and repairs. A leak on the helium seal around the void vessel has been found and cured, and a 4616 valve is being changed in the linac RF power chain. During accelerator set-up last night, some quirks in the new accelerator timing system were noted and are being investigated.
This afternoon the accelerator physics team will continue refining the beam set-up with base rate beam to target 1.
At 18:00 the target, reflector and moderator assembly was moved forward into the operating position at the centre of the second target station monolith.
The accelerator is now being set up and base rate beams are being sent to target station 1. This is a great step forward after the numerous small delays of the last few days.
Early tomorrow morning, the void vessel that surrounds the target system will be evacuated and then filled with helium. Before beam can be sent to target station 2, there are a few remaining checks on the water cooling system, electrical supply to the cryogenic systems and the ventilation systems.
Everyone is very pleased to have reached this point, and there is a good mood across the project.
Around 17:30 yesterday evening, hopes of running beam to target were dented after a fire in the 12,000 Amp injection dipole pulsed power supply in building R4 destroyed one of the transformers. The injection dipole magnet is part of the link between the ISIS linear accelerator and the synchrotron.
However, after a hard evenings work removing the burnt-out transformer and some wizard wiring by the electrical engineering group, the power supply is now back online. Latest reports are that it has reached full power 12,300 Amps at 50 Hz and the accelerator is ready to operate again.
Final checks are being made in the target station ready to push forward the target into its operating position. Later this afternoon, R80 will be searched and cleared to allow the accelerator team to tune-up the accelerator and send beam to Target 1.
The roof shielding over the remote handling cell has been installed and final shielding checks from the synchrotron to the target services area are taking place now.
This afternoon the Inter beamline was cleared to receive beam after passing live interlock checks. Inter is now ready to receive neutrons. With the accelerator operating in minimal mode (with the ion source beaming to the low energy beam transport beamstop - just before the RFQ and linac), the Inter shutter was opened and the instrument interlock system was challenged. All tests were passed on this new style of neutron beamline interlock system that meets with new safety requirements. The Inter shutter has now been closed again and locked shut.
Leak testing on the target and moderators is underway. It is anticipated that the target can be moved into its operating position overnight or early tomorrow morning, in preparation for low repetition rate beam to target (one pulse every few seconds).
Beam to the new target station will be delivered in two stages. Firstly, with all instrument beamline shutters locked shut; and secondly, with the Inter shutter open to allow for first measurements of neutrons in a neutron beam line instrument.
Target position repeatability tests have gone very well today and the final positions of the target, moderators and reflectors can be set. This evening, the moderators and reflector will be aligned with respect to the target, and the pipework connections will be made. Overnight the remote handling cell will be cleaned and painted.
Commissioning work on the hydraulic shutter drives has been completed. In an impressive test carried out overnight, all shutters were raised open and the power removed. The shutters held their position to 0.1mm on the hydraulic system alone.
Tomorrow, the ion source and the stripping foil in the synchrotron will both be changed to minimise risk of accelerator downtime. The roof of the remote handling cell will be fitted, and the moderators and water cooling circuits will be tested for leaks.
Base rate beam to target is now anticipated for early Wednesday morning.
Teams continued working yesterday night and this morning to ensure that the tungsten target is correctly positioned with respect to the incoming proton beam. The target is just 36 millimetres in diameter and 66 millimetres long. The target sits at the centre of the shielding monolith, the 12 metre high, 7 metre wide steel and concrete structure that has been built in the middle of the Second Target Station experimental hall. Once the first pulse of protons has been fired at the target, it will be extremely difficult to access this area again.
Meanwhile, tests of the safety interlock system along the proton beam tunnel and in the target services have been passed. The accelerator control team are making some adjustments to the central timing system which synchronises all parts of the accelerator.
A final inspection of the shielding around the target station, proton beam and instruments will take place this afternoon.
Over the coming days, project teams will be working to produce first neutrons. A mood of tense excitement can be felt across the project as extremely hard work continues through this critical period.
Final checks on the target systems are being made and the cryogenic systems are cooling down. The interior of the target station is being cleared in preparation.
The second proton beam has been reconfigured for running from the main ISIS control and interlock systems.
The Inter instrument is fully prepared to receive the first neutron beams once all safety and interlock checks have been completed. All other beamline shielding has been installed and instruments locked off.
The ISIS main control room will be issuing updates via MCR news.
With only a few days before the target station is closed up in readiness for first neutrons, we took the opportunity to walk around the project and look in some places where we're never likely to go again.
The target and reflector assembly were being surveyed into position, and the we watched the movement of the target from its operating position in the centre of the monolith to the maintenance position in the remote handling cell was being tested.
Inter will be the first instrument to detect neutrons. Neutron detectors were being installed and motion control hardware was tested. Proof testing of the instrument interlock system was underway, as was commissioning of the hydraulics for lifting open the neutron shutters.
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