From achen@triumf.ca Mon Jul 15 10:23:32 2002 Date: Mon, 15 Jul 2002 10:18:40 -0700 From: Alan Chen To: Dave Hutcheon , DRAGON minutes -- Alan Chen , Ahmed Hussein , Alison Laird , Dario Gigliotti , John D'Auria , Jennifer Fallis , Hart Sprenger , Don Hunter , Cybele Jewett , Joel Rogers , Peter Jackson , Lothar Buchmann , Peter Machule , Michael Lamey , Mohan Lal Chatterjee , Art Olin , Dave Ottewell , Peter Parker , Doug Preddy , Rachel Lewis , Sabine Engel , Shawn Bishop , Uwe Greife , Chris Wrede Subject: Minutes (attachments to follow) DRAGON meeting - Tuesday, July 9th 2002 Present: AH, DAH, MC, CW, JF, AC, ML, DO, AO, DG 1. No minutes from last week 2. MCP tests - ML - 20Ne, 360 keV/u - ML showed spectra from the 4 position signals. One of the channels showed a low-energy sharp peak, which resulted in two peaks in the vertical position spectrum. The cause of the sharp peak is unknown, but further tests are planned. AO mentioned that it might be related to electronics or ADC gating. - Timing between MCP and DSSSD was about 4 nsec. As the MCP discriminator threshold was lowered, multiple timing peaks were seen. For the high threshold measurment, the MCP efficiency relative to the DSSSD was about 99%. - The X-final-slits were closed to 1mm, and spectra were taken at two positions separated by 1 cm. A clear separation between the two peaks corresponding to the horizontal positions was observed. - It was observed that the width of the vertical position peak worsened as the Y-final-slits were opened from 2mm to 5mm. The cause is unknown. MC raised the possibility of increased scattering from the slits, and suggested that the mirror voltages be increased to guide more effectively secondary electrons from the scattered beam into the MCP. He also mentioned that the mirror wires might be too slack, thereby resulting in different path lengths for the electrons. - Further running planned for Thursday evening. 3. Other stable beam tests (DAH) - An attempt was made to view light from the gas target due to the beam. A window was set up at MD1 and an theodolyte was used. No light was seen with either H2 or He gas. One possibility is that visibility is hampered by the fact that the light's wavelength is in the red region. The possibility of using a CCD camera for future tests was raised. - A measurement of beam energy via TOF through the separator was attempted. The measurement sought to detect alphas scattered into the DRAGON from 20Ne + 4He elastic scattering. Although the expected counting rate was 1/sec, no events beyond background were observed. 4. AOB - DO reported that our Leybold dry roughing pump was unusually noisy. A Leybold rep came by and was shown the problem. He is now going to look into it further.