H9 consists of 32 identical scintillators (pink in the above figure): two rows of 16, to roughly match the geometry of the C9 mirrors. Each scintillation paddle covers approximately one of the smaller size columns of the C9 mirrors.
Each of the Bicron BC-408 scintillators measures
(39.250" +/- 0.010") x (6.125" +/- 0.010") x (0.250" +0 -0.007"), or
(99.695 +/- 0.025) x (15.558 +/- 0.025) x (0.635 +0 -0.018) cm
prior to wrapping with aluminum foil and black paper. The top and bottom paddles are taped together end-to-end in an overlapping fashion as shown in the figure below; each scintillator makes an angle of roughly 30 degrees from the vertical (a more precise measurement of the angle is given later). The scintillation light is carried through a light pipe consisting of 4 twisting fingers of 9mm thick Acrylite OP-1 which is manufactured by Cryo Industries of Orange, CT. We measured an attenuation length of about 1.3m at 400nm wavelength and about 2m at 450nm wavelength for samples of the Acrylite OP-1. At the end of the lightpipe is a transition piece followed by a Philips XP2262B photomultiplier tube and a model "PMTB-XP2262-A" base manufactured by Vorg Electronics of Yorktown, VA.
The positions in MPS coordinates of each hodoscope paddle are given in the table below, where the Y and Z coordinates and the hodoscope angle are defined as shown in the previous figure.
| angle | angle | ||||
| of top | of bottom | ||||
| paddle | paddle | paddle | X, center | Y, apex | Z, apex |
| no. | (degrees) | (degrees) | of apex | ||
| wrt horiz | wrt horiz | (cm) | (cm) | (cm) | |
| 1 | 58.0 | 56.4 | -115.669 | -0.175 | 560.03 |
| 2 | 56.8 | 56.2 | -100.032 | -0.058 | 559.82 |
| 3 | 58.0 | 56.4 | -84.315 | -0.058 | 560.32 |
| 4 | 58.0 | 56.6 | -68.520 | 0.003 | 560.87 |
| 5 | 58.0 | 57.0 | -52.804 | -0.041 | 561.17 |
| 6 | 58.0 | 57.0 | -36.929 | -0.104 | 561.44 |
| 7 | 58.0 | 56.8 | -21.213 | -0.152 | 561.75 |
| 8 | 58.0 | 56.6 | -5.734 | -0.058 | 561.57 |
| 9 | 58.0 | 57.4 | 9.982 | -0.191 | 561.44 |
| 10 | 57.5 | 57.0 | 25.618 | -0.191 | 561.55 |
| 11 | 57.5 | 56.8 | 41.255 | -0.224 | 561.50 |
| 12 | 57.5 | 56.8 | 56.971 | -0.061 | 561.25 |
| 13 | 57.0 | 56.2 | 72.607 | -0.150 | 561.28 |
| 14 | 57.0 | 56.4 | 88.243 | -0.119 | 560.99 |
| 15 | 57.5 | 56.4 | 103.881 | -0.142 | 561.14 |
| 16 | 58.0 | 56.6 | 119.597 | -0.043 | 561.36 |
| average | 57.7 | 56.7 | -0.110 | 561.09 | |
| midpoint | 1.963 |
The positions given in the above table are for the 1997 run only, and they are accurate to about 1/16" (0.16cm). There is a spreadsheet (sc) file which was used to calculate the above numbers; this file would be useful, for example, if the hodoscope is moved into a different position for a future run. No supporting documentation is being provided with the spreadsheet file at this time.