PMT HV Base Board Status and Discussion Materials
9/8/2003 Nobuyoshi Kitamura
Iseg Matters
NK's report on 2003 "New Iseg" prototypes sent to Iseg (8/14/2003). In this report NK very politely points out numerous problems with the Iseg prototypes. Iseg's response to NK's report (8/29/2003) is a translation of a sales engineer.
Failed capacitor in one the 2002 "Old Iseg" prototypes is shown here. Arcing was observed at this capacitor location when DAC value of 4000 (dec) was written (corresponding to 2000V).
Three Old Iseg bases have been integrated into a DOM. Of those three:
One exhibited the arcing failure
One was initially malfunctioning due to a dropped out component (from rework at PSL--not Iseg's fault)
One has an intermittent failure (lack of HV, needs more characterization)
George Anderson helped me to identify the board layout problems. See the photo presentation: Iseg Board Layout Examination
Iseg Bases in AMANDA--a history according to Jerry Przybylski, Azriel Goldschmidt, and Albrecht Karle.
Iseg corporate facts (sent to NK on 9/2/2003)
EMCO?
The EMCO / Passive Base Option consists of three components:
HV generator module. This component is drop-in replaceable with one from an alternative source. See Outline and specification of EMCO 9730 HV module.
Digital interface. This has been fully developed and functional. The interface board, mounted on the flasher board, serves as a carrier for the HV generator module.
Passive resistor bleeder chain board (base board). EMCO has provided us a prototype, which turned out to have an error in the circuit. The base board may be delivered by many alternative sources, including DESY / Zeuthen. The engineering requirements include a high total resistance (~150MOhm) and the use of a toroidal transformer for the output pulse coupling.
"The Action Item Thing"
It is possible to construct a toroidal transformer (used for PMT pulse coupling) with a satisfactory performance and a sufficient voltage margin by winding a pair of silicone-rubber-insulated wires on a toroidal ferrite core. See Toroidal transformer design alternatives.
