Final Version

                                                                                      8/25/99

 

 

HNSS Readiness Review

 

 

            At the July 29, 1999, Final Readiness Review the HNSS Collaboration updated the committee on the significant progress which has taken place since the last review approximately 6 months ago. We believe that, if progress continues at this pace, the experiment will be ready to run at the scheduled time and has a good chance of being a successful test run of the HNSS.

All "Issues" raised at the last review are essentially closed. No new issues were raised.

Most of the previous "Concerns" were addressed. A few new concerns arose.

            We are also listing some straightforward items at the end which don't cross the threshold of being concerns but are worth mentioning.

 

 

RESOLVED ISSUES:

 

 

1. Generate a Project Schedule and Resource Allocation Table

 

            The Collaboration has submitted a schedule which works.  This issue is closed.

 

2. Develop a Downstream Beamline Design

 

The Collaboration and many Jlab groups have worked hard on this.  As an issue this matter is substantially closed.  However, a list of miscellaneous remaining items is included at the end of this report.

 

3. Determine the Actual Beam Quality Requirements

 

The Collaboration has worked very hard to maximize the likelihood of their receiving beam energies stable (or at least trackable) to 1E-4, with an energy spread which is negligible compared to the SOS.  They have communicated their wishes in several meetings with Accelerator Division, commissioned software to track beam energy shifts based on BPM readbacks from EPICS, requested a fast energy lock of the type used in Hall A, tested a fast orbit lock in Hall C (which exercises some of the required fast energy feedback infrastructure), updated the Superharp software and documentation used to check the energy centroid and spread, commissioned an optical transition radiation device to measure the beam energy spread (perhaps continuously), and are planning to monitor the 3C Dipole string temperature and fields to verify the 3C ARC magnets are always on loop.  Recent measurements with Superharps and the OTR device indicate the beam energy spread will routinely be a smaller contribution than the SOS to the overall resolution.  We consider this issue closed.

 

 

 

NEW OR OUTSTANDING ISSUES:

 

None.

 

RESOLVED CONCERNS:

 

 

1. Manpower

 

            The manpower table has been updated, and has stated that it has no conflicting commitments at BNL.  This is no longer a concern.

 

2. Data acquisition infrastructure

 

General detector electronics infrastructure is much better defined now.  This is no longer a concern.

 

3. Coupled vacuum systems & 7. Enge spectrometer safety

 

These concerns are inherently coupled.  They remain a concern, but the following proposal is a good place to start.  Something like the following will have to go into the ESAD for the Experiment:

 

The stray fields in the vicinity of the Detectors are only 50 Gauss and not a high hazard for pulling small magnet materials into the window.  At all times, any work in the close vicinity of the vacuum window requires first emplacing the window shield.  (The Physics Division Liaison will define "Close Vicinity" for you).  This shield must be designed so that its installation does not present an even greater hazard than omitting the shield.

 

I) Detector installation/de-installation: The Enge must be up to air.  The magnet must be de-energized.  This is inherently a "Close vicinity" operation, so the window shield must be installed.  When work is complete, remove the shield.

 

II) Normal data taking operations: The Enge is under vacuum.  The magnet is energized.  No personnel are in the Hut.  The Detectors cover a large fraction of the vacuum window.  The uninstrumented remainder of the window will be covered with a shield.

 

III) Minor detector repairs: The Enge is permitted to be under vacuum.  This may be a "Close Vicinity" operation.  If so, the magnet must be de-energized and the window shield must be installed.  When work is complete, remove the shield. If not a "Close vicinity" operation, then the magnet is permitted to be energized while repairs are in progress.  Contact the Physics Division Liaison if there is any question about the definition of "Minor Repair".

 

 

IV) Major detector repairs: Any major repairs should be treated under the same rules as for Detector installation/de-installation.  Contact the Physics Division Liaison if there is any question about the definition of "Major Repair". 

 

V) Detector debugging: The Enge is permitted to be under vacuum.  The magnet is permitted to be energized.  This may be a "Close Vicinity" operation.  If so, the window shield must be installed.  When work is complete remove the shield.

 

 

 

4. FSD for the splitter magnet needs further study and a well defined plan.

 

 

A plan exits. This is no longer a concern.

 

 

5. Hodoscope time resolution:

 

            The Collaboration chose to modify the design and so achieved much better time resolution.  The prototype resolution of better than 300 ps (sigma) will be an asset to the experiment.  This is no longer a concern, but see below.

 

 

 

NEW CONCERNS:

 

1. SOS vacuum quality:

 

Tying the HNSS/SOS/Scattering chamber vacuum into our beamline vacuum is a problem which needs to be addressed.  In general beamline vacuum is at 10-6 but the SOS is currently at 10-3.  We need more pumping on SOS and will possibly need to "isolate" the beamline vacuum from the target.  This could be done with a small input pipe from the beamline to the target chamber to limit conductance towards the BSY.  Jim Parkinson will look into this.  Also, Tang is getting a turbo pump from Houston that we can hookup to the SOS to boost the pumping speed.

 

 

 

 

 

2. Operational procedures for new equipment:

 

There will be several new and specialized devices (Enge spectrometer, SSD) that will be operated by experimenters during this time.  Unless they expect to have experts on these systems man shifts 24 hours a day, detailed dummy proof operating procedures and GUI's need to be implemented for these devices.  We did not hear anything about this, so presumably the bulk of the effort is still in making the devices work. Some investment in controls/operations will pay off when the experiment begins.

 

 

3. Commissioning plans:

 

Commissioning plans need to be made for the new equipment. Studies need to be done to see if there are unexpected sources of background. How do they plan to go about determining if there is a background problem and what might they do about it? Some special histograms or simple programs, which look at scaler rates and/or ratios, may be needed.

 

4. Hodoscope schedule

 

            As part of the redesign, the number of Hodoscope channels increased.  A better PMT was ordered and their arrival is awaited.  A new UVT acrylic lightguide was designed which requires labor intensive bending. This is a big job but there is time.  The collaboration must be draconian about maintaining the schedule.

 

5. Operational procedure in case beam energy spread is unacceptable:

 

This will be the first Hall C experiment in which the beam energy spread has to be carefully controlled. Not only must the energy spread be monitored with the OTR, but a clear procedure should exist for what to do if the energy spread is above some threshold. Presumably the Run Coordinator would be contacted by the shift crew, and the Run Coordinator would consider whether to request that the MCC reduce the energy spread. That would require a retune of the accelerator which may bring all three halls down. If Hall C is not the priority hall then the request may be refused.

 

6. Operational procedure for opening SOS door:

 

            A relatively rapid and "fail-safe" procedure is needed for opening the SOS detector hut door. There will be a section of beam pipe beneath the SOS door. The potential exists for damaging that pipe if it is not removed before the door is opened. We recommend that Bill Vulcan or designate retain the only key for activating the SOS door hydraulics. This person will be responsible for first ensuring that the beam pipe has been removed with approriate RadCon support, and then opening the SOS door. After work in the SOS detector hut is completed (and everything has been verified to be still working), the process can be reversed.

 

 

MISCELLANEOUS:

 

 

1. The Safety group needs to review the bunker design for Run/Safe boxes and anything else they may need.

 

2. Unfortunately, survey help will be in high demand during January 2000, which is a real scheduling problem.  However, as in the past it is usually Physics competing with Physics so it is a matter of priority setting by L. Cardman.  It has been worked out in the past and there is no reason we can't in this case.

 

3. The dump line design needs to be firmed up as far as how the pipes/correctors/viewers are supported and aligned.  This is mainly critical because there are now substantial lengths of 2" pipe 13' in the air and traditionally Hall C has had some poor pipe supports which made placing them difficult.

 

 

 

Attachments: "Charge to Hall C HNSS Readiness Review Committee" and "Readiness

Review Guidelines"