Last modified: Jignesh Parikh 15 Mar 2002
The Prototype II drift chamber (Proto II) is a full-scale mockup of the BaBar Drift Chamber, covering a narrow angular region (1/8, 45°) of the first four superlayers. It is installed at SLAC in Central Lab Annex B273.
This document describes how the detector hardware is installed, and how to update the data-acquisition firmware as needed. A more detailed description of the hardware is included in Lisa Manning's project report.
The Prototype II trigger consists of a three-fold coincidence of scintillator paddles, one above the chamber, one immediately below, and one below a 62 cm steel range stack.
Plateau and relative efficiency curves were taken for all three scintillators (see links below) to determine the PMT voltage and discriminator settings.
Operating conditions of proto II in the gas chamber are monitored using the following sensors:
|Number||Sensors||Location on detector||Input Range||Supply (V DC)||Output (V DC)||Connector Type||Company||Model|
|1||press_atmosphere||(P1)||0-30Psi||5||0.5-4.5||3-pin lemo||Kavlico corp||P350-30A-D1A|
|3||temp_front_gas||Front End||0-100C||2||0.135-0.67||3-pin lemo||Omega||OL 710|
|4||temp_rear_gas||Rear End||0-100C||2||0.135-0.67||3-pin lemo|
|5||temp_front_cover||Front End||0-100C||24||1-5||1-pin lemo||Omega||HX 13V|
|6||temp_rear_cover||Rear End||0-100C||24||1-5||1-pin lemo|
|7||rh_front_cover||Front End||5-95%||24||1-5||1-pin lemo||Omega||Omega|
|8||rh_rear_cover||Rear End||5-95%||24||1-5||1-pin lemo|
|9||volts_anode||Voltage(1930V)||0-5KV||10V=10KV||0-5||1-pin lemo||Bertan Associates, inc.||1755P|
|12||current_anode||Current(1930V)||few nA||10V=1mA||0-5||1-pin lemo|
|13||current_cathode1||Current(335V)||few nA||10V=1mA||0-5||1-pin lemo|
|14||current_cathode2||Current(870V)||few nA||10V=1mA||0-5||1-pin lemo|
|15||flow_helium||He Flow||0-1 SLPM||N/A||0-5||3-pin lemo||Sierra instruments, inc.||840-L-1-V1-S1|
|16||flow_c4h10||C4H10 Flow||0-1 SLPM||N/A||0-5||3-pin lemo|
|17||flow_nitrogen||N2 Flow||0-250 SCCM||N/A||0-5||3-pin lemo||Sierra instruments||840-L-2-0V1-SK1-E-V1-S1|
Front-end electronics are water-cooled. Front-end and read-out electronics consist of two Front-end Assemblies (FEAs), a data I/O Module (DIOM), a triggered Read-Out Module (ROM), a Fast Control Distribution Master (FCDM), and a Fast Control Partition Master (FCPM). Input triggers are processed by the FCPM and FCDM, then distributed to the ROM. The ROM collects data from the drift chamber front-end electronics and ships it to data acquisition system.
On the real chamber, there are four DIOMs, each reading out one quadrant's worth of data. Each DIOM is configured for its quadrant via a jumper attached to its J12 connector. For Prototype II, we have prepared four jumpers, so that the hardware and software can emulate any part of the real detector. The quadrant selected must be matched to the ROM's identification number.
The two front-end elements have separate cables connecting them to the DIOM. The four DIOM connectors labelled J10, J8, J7, and J5, correspond to the four wedges in each quadrant of the real BaBar drift chamber. Any two of the connectors can be used, so that the readout system can emulate any portion of the real chamber.
The data acquisition system consists of a BaBar TPC Readout Module (ROM) and a Fast Control Partition Master in a 9U VME Crate. The ROM is connected to the front-end DIOM with a dual fiber-optic cable. The ROM is based on a Motorola 68040 CPU, and runs the VxWorks operating system, with the standard BaBar Online Data Flow (ODF) core and DCH-specific applications.
The ROM has an eight-bit identification number which is set via DIP switches on the back of the module. For the drift chamber software to function correctly, the ROM ID must match the quadrant jumper selected for the Data I/O module.
Note: The installed version of the core DataFlow software does not permit an isolated ROM (as we use on Proto II) to be configured with ROM ID 0. We can only set up Proto II as quadrants 1, 2, or 3.
Periodically, the core ODF group will release an update to the core software, which should be installed in the Proto II ROM flash memory. The installation process is straightforward, but must be followed carefully to avoid leaving the ROM in a unusable and inaccessible state.