GUIDE TO DATA TAKING IN HALL A
Bob Michaels, v2.4, May 2001
pager: (757)-881-7897, e-mail: rom@jlab.org
This file :
hallaweb.jlab.org/equipment/daq/guide.html
This is information about how to run DAQ in Hall A, as well as how to configure the trigger and use the ``online'' codes. See also hallaweb.jlab.org for useful links such as ESPACE, the offline code.
I. Where to Run Things
Below is a table showing where to run the different codes using the public accounts adaq, adev, atrig, a-onl, and apar. The run coordinator should know the passwords.
| Code | Computer | Public Account |
| CODA (runcontrol) | various (see table below) | see table below |
| ESPACE | adaql1 or any Linux box not running CODA | adaq |
| trigsetup | adaqlN (N=1,2...) Linux | atrig |
| dataspy | adaqs3, or h2 (Sun or HP-UX) | adaq or adev |
| dhist | adaqs3 or h2 (Sun or HP-UX) | adaq |
| xscaler | adaqs3 or h2, NOT s2 | adaq |
For summer 2001, we have split the two Hall A Spectrometer DAQ systems. The Left Spectrometer runs on adaqs2 on the adev account. The Right Spectrometer runs on adaql2 on the a-onl account. In addition, the Parity DAQ is available for test of helicity correlations; it runs on adaqcp on apar account. From the usage standpoint, these DAQ setups are quite similar, see also section III.
| Attribute | |||
| System being read out | Left Spectrometer | Right Spectrometer | Parity DAQ |
| Computer where to run | adaqs2 (SunOS) | adaql2 (Linux) | adaqcp (Linux) |
| Account from which to run | adev | a-onl | apar |
| ROCs involved | ROC2, ROC14, TS1 | ROC1, ROC15, TS0 | ROC1 (crate in cnt room) |
| BPM Crate | ROC14 | ROC15 | |
| Disk areas for data | /adaqs2/dataN, N=1,2... | /adaql2/dataN, N=1,2... | /adaql2/dataN/parity, N=1,2... |
| Run numbers | sequence below 20,000 | numbers > 20,000 | |
| Prescale factors | ~adev/prescale/prescale.dat | ~a-onl/prescale/prescale.dat | |
| Deadtime and Disk monitor | datamon (from adev) | datamon (from a-onl) | |
| runcontrol configuration | LeftSpect | RightSpect | happex1 |
| runcontrol config for pedestals | pedrunL (L means Left) | pedrunR (R means Right) | |
| Location of pedestal files | ~adev/ped/ped2.dat | ~a-onl/ped/ped1.dat | |
| Location of scaler_history.dat | ~adev/scaler/ | ~a-onl/scaler/ |
II. General Computer Information
Computers: adaqs1 will be the Compton DAQ computer. It should be avoided, e.g. the paths are different. adaqs2 and adaql2 are used for spectrometer DAQ. adaqcp is for Parity DAQ. adaql1 is for running online ESPACE analysis, etc. adaqh2 is the lone remaining HP-UX. The Linux boxes like adaql1, adaql2, adaqep, adaqcp are the best places to run ESPACE, but the ones where CODA is running should be avoided. Note the large amount of ``work'' disk on adaql1 and l2 where you may keep scratch files like hbook. The disks are /adaqlN/workM where N=1,2... and M=1,2,3...etc.
How to reboot workstations (rarely necessary): On SunOS its possible to do a quick reboot which can fix some hangups. Login as adaq account and type "reboot". On HP-UX you have to shutdown (cannot reboot). NOTE: If power fails you must do a shutdown before the UPS battery goes bad. Login as adaq and type "shutdown". After several minutes, the screen goes black, wait a bit more, then power off. When power comes back, computer reboots. (Eccentricity of adaqs2: When it comes back from shutdown, there may be sign "ok" where you have to type "boot". Also, don't forget to type "xhost +adaqs2" when you login as adev.) Linux: Hit Ctrl-Alt-F1 to go to console mode, then Ctrl-Alt-Del, or see Ole's instructions which might be posted near the terminal.
III. CODA
Detailed information about running the spectrometer DAQ in Hall A as well as the Parity DAQ may be found below. There are two modes of running spectrometer DAQ in Hall A : (i) The "coincidence" setup, also called the "1-Trigger-Supervisor" mode because it uses one trigger supervisor; and (ii) The "single-arm" setup, also called the "2-Trigger-Supervisor" mode because it uses two trigger supervisors to run two completely indendent DAQ systems.
If you are doing a coincidence experiment, you must use mode 1). Mode 1) can also handle single-arm triggers, of course, but is limited in speed to about 1/2 the aggregate speed of mode 2).
Here is the guide, which was written in a sufficiently general way to apply to each of the independent DAQs:
hallaweb.jlab.org/equipment/daq/guide2.html for CODA 2.x setup (read this if nothing else).
Also available are documentation about the raw data structure and frequently asked questions about DAQ deadtime.
IV. Trigger
The spectrometer trigger was described in some detail in the OPS manual. Here I give a superficial overview and describe how to download a new setup. First, here are some simplified instructions to download and check the trigger:
hallaweb.jlab.org/equipment/daq/trigger.html.
Though coincidence triggers are not used in the summer 2001 running, here are some detailed specific information about the coincidence trigger setup:
hallaweb.jlab.org/equipment/daq/trigsetup_coinc.html.
Overview of trigger: Scintillators make the main trigger in each spectrometer arm, and a coincidence is formed between the spectrometer arms. The main trigger is formed by requiring that scintillator planes S1 and S2 both fired (and both phototubes in each paddle) in a simple overlap. The trigger requires that S1 and S2 fired. The coincidence between spectrometer is formed in an overlap AND circuit. The Right Spectrometer singles triggers are called T1, the Left Spectrometer triggers are called T3, and the coincidence triggers are T5. Other triggers might be formed which require other detectors. The most important is T2 on R-arm and T4 on L-arm, which are identical, and require 2 out of 3 from among the S1, S2, and Cerenkov detectors (i.e. the "or" of S1 is used, etc). Such a "loose" or "majority logic" trigger allows to measure the efficiency of the main trigger. The experiment should always keep about 5 - 10 Hz of these loose triggers.
Downloading the trigger: For coincidence experiments, it is forseen that the only change between kinematic settings that affect the trigger are delays that track with the momentum. To change the trigger, login to a linux PC like adaql1 or l2 in the "atrig" account (ask run coordinator for the password) and type from anywhere "trigsetup". This starts a GUI whose usage is obvious. Further details are at the link above (trigger.html).
For single arm experiments (like e99117 and e97103), you probably never want to change the trigger. But it would be wise to download the default trigger file from time to time. Also, if the power is lost on the CAMAC crate, you must download again.
V. Scalers and Scaler Display
Normally this is already running on adaqs3. (It also runs on HP-UX, but the Sun version is preferred, and it may cause deadtime if run on adaqs2 where CODA runs). If not running, login as adaq, and go to the appropriate directory, which is (1) ~adaq/$EXPERIMENT/right/scaler for right arm, and (2) ~adaq/$EXPERIMENT/left/scaler for left arm. ($EXPERIMENT is an environment variable, like e99117.) Then type "xscaler". Remember to push the button "Start". For experts: The configuration of scaler information is controlled in a file scaler.config in the appropriate directory.
More about scalers: Scalers are read periodically during a run and injected into the data stream as event type 140 and decoded by ESPACE. They are also read and injected at the end of the run. A file scaler_history.dat is maintained which is a complete history of scaler readings at the end of the run. These files should be in ~/scaler for the adev and a-onl accounts.
VI. Online Codes for Spectrometer
There are two codes of interest for doing online diagnostics of raw data, in addition to using ESPACE. They are: (1) dataspy, and (2) dhist (actually dhist is a shell script). To run dhist, simply type "dhist". Though it should run anywhere, lets be definate: Log onto adaqs3 as adaq account (e.g. via ssh from adaql1) and type "dhist". You will see a reminder that you have to go to the proper directory and type "./dhist" there. Just do it. To run the optional interface that turns on/off histogram pages and that shows the alarm status for comparing histograms to references, type "dopte" and "dopth" for E-arm and H-arm respectively. The dhist script runs "dplot" on online data which it gets off the net in real time, and "dplot" is a code that pops up some HIGZ windows and displays several pages of raw, uncut, data as self-explanatory diagnostics. More details about the dataspy/dataplot codes may be found at
hallaweb.jlab.org/equipment/daq/dplot.html
By default, the online codes obtain data from ET system, hence cannot cause deadtime. If one uses "espace" to read a the currently written file, one might cause deadtime. One way around this is to start on the present file at the end of a run, or to choose another file. However, below 1 kHz CODA rate, reading the file should cause no deadtime.
Recently ET system was implemented for ESPACE. See jlabs1:/home/rom/espace2.8.2/src/r2-8/README_ET for details.
VII. Parity Analysis
Antonin Vacheret will maintain a HOWTO manual for obtaining charge asymmetry among other things from the Parity DAQ.
R. Michaels -- e-mail: rom@jlab.org