1 of 5 10/2/2007
Butch report (L.A.Dillon-Townes) Updated by S.N.Nakamura (20070926)
This report will present the issues that were discussed during my visit at Tohoku University September 2007.
There are six (6) areas of discussion presented:
- Splitter
- Target Ladder
- Radiation Shielding Definition
- HES Spectrometer
- Operations
- Layout Parity Communication
- Schedule of interface deliverables
1. Splitter
1.1. Post Target particle scatter – The particle scatter envelop from the target impacts the ebeam exit port. Figure 1.
1.2. Splitter exit -to-HES entrance – The interface between the splitter flange and the spectrometer requires a design to incorporate the Sieve Slit(SS) to the EQ1 and the variable spacer spool. The variable spacer spool will accommodate the tilt angles of the spectrometer.
1.3. Fringe fields at splitter entrance – Shield beam tube before the entrance of the splitter to improve the location accuracy of the ebeam-to-target interaction. A iron pipe shield will be considered to mitigate the potential error at the interaction point.
1.4. Interchangeable Splitter stand spacer– Confirm the length of the splitter stand spacer which accommodates both HALL C and HALL A installations and transmit file to Tohoku University. Figure 2 & 3.
1.5. Alignment Procedure– An alignment procedure should be generated and reviewed to ensure Splitter and its’ interfaces are designed and installed with confidence (e.g. HES-to-SS-to-Spacer- to-Splitter exit).
2. Target Ladder
2.1. Water Cell Target – A water cell target is desired in the target ladder for HKS/HES calibration source. An acceptable design is needed to incorporate this cell. The design must also provide an adequate camera viewing angle for all target cells.
2.2. Target Camera selection – CCD vs Conventional camera recommendation is needed to ensure survival for the entire experiment.
2.3. Beam Raster Size – Will the ebeam be rastered for the water target calibration runs? Tohoku University’s desire is to have no raster for these runs. Discussion is needed to resolve the issue.
3. Radiation Shielding Definition
Shielding volume and location – A review of the experimental layout to designate locations and volumes for shielding should be done.
4. HES Spectrometer Access
Personnel Access – Commissioning and maintenance activities will require safe personnel access to many of the components of the spectrometer.
5. Operations
5.1. Channels – Are there sufficient instrumentation and signal channels?
5.2. Beam Momentum – EPICS- reliable? Accuracy (10-5 )?
5.3. Viewer Limitation Mode – When HALL C viewers are used are other halls affected?
5.4. Energy and Position Locks of fast feedback – Both of energy and position lock to Hall C are necessary during HKS/HES runs.
6. Schedule of Target Ladder and Splitter Interface Designs
Basic target design will follow one used for HKS experiment. Water cooling system and water cell target R&D will be carried out by Tohoku group with a help of JLab engineers.
Splitter interface should be designed as soon as possible after the beam energy is fixed. Once the beam energy is given, optimized tilt angle and offset for HES will be calculated by Tohoku group. The flange of the interface will be designed by JLab engineers and Tohoku scientists and fabricated by JLab.
Beam profile at the SPL vacuum chamber exit to HES
Units are centimeters and blue points refer to scattered electrons which pass through 8degrees tilted HES (Pe’ = 967MeV/c). The red points do scattered electrons which passed through 6 degrees tilted HES.
Black points are primary electron beam (2.467GeV). Photon line locates at (-70.2,0).
Dots density of the scattered electrons is enhanced for clear view.
Photon beam pipe is 3” f (inner) and
ebeam pipe should be larger than 6”x2” (inner).
FIGURE 1
LAD-T J:\JLAB_WORK\HALL C\HES_HKS_09\Sendai Trip Report body 20080925-Nue.doc