GUIDE TO DATA TAKING IN HALL A

Bob Michaels,     v2.3,     Jan 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.  General  Computer Information

Below is a table showing where to run the different codes using the public accounts adaq, adev, and atrig -- for the case of one single DAQ setup that controls both spectrometers.  The run coordinator should know the passwords.  

Where to Run Online Software in Hall A Counting Room

Code	Computer	Public  Account
CODA  (runcontrol)	adaqs2  (backup: s3)	adev  (s3: atrig)
ESPACE	prefer adaql1, l2, or s3	adaq
trigsetup	adaql1 or l2	atrig
dataspy	adaqs2,s3, or h2	adaq or adev
dhist	prefer adaqh2	adaq
xscaler	adaqh2,s3,   NOT s2	adaq
ha_analyzer	adaqh2	adaq

Computers:   adaqs1 will be the Compton DAQ computer. It should be avoided, e.g. the paths are different.  adaqs2 and s3 are for spectrometer DAQ, running online and ESPACE analysis, etc.  adaqh1, h2, h3 are to be shared by the remaining tasks that need HP-UX, e.g. the e-P energy apparatus.   Fast linux boxes adaql1, l2 (l=linux) are the best places to run ESPACE. One may also use linux boxes adaqep and adaqcp. Note the large amount of scratch disk on adaql1 and l2 where you may keep scratch files like hbook. The disks are /adaqlN/dataM 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 posted near the terminal.

 I I.  CODA  

Detailed information about running the spectrometer DAQ in Hall A may be found below. There are two modes of running 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 are the guides, which include information about how to run CODA, where the data is, how to adjust prescale factors, what the deadtime is, etc :

hallaweb.jlab.org/equipment/daq/guide2.html  for CODA 2.x setup (read this if nothing else).

The old 2.x guide is supplemented in recent times by the guide for running the 2-TS-mode: hallaweb.jlab.org/equipment/daq/twodaq.html

Also available are documentation about the raw data structure and frequently asked questions about DAQ deadtime.

III.  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.

And here are some detailed specific information about the coincidence trigger setup:

hallaweb.jlab.org/equipment/daq/trigsetup_coinc.html.

Overview:  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. Prior to Jan 2001, a memory lookup unit (MLU) was used to decide if the paddles that fired belong to an allowed set which required a track at approximately 45 degrees (within some tolerance). But now we don't use this MLU anymore.   The trigger simply requires that S1 and S2 fired.  The coincidence between spectrometer is formed in an overlap AND circuit.  The Right Spectrometer (formerly called E-arm package) singles triggers are called T1, the Left Spectrometer (formerly called H-arm) triggers are called T3, and the coincidence triggers are T5.   Other triggers might be formed which require other detectors, but these won't be described here.

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 e94010 or e95001), you probably never want to change the trigger. But it would be wise to download the default trigger file from time to time.

IV.  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 e94104.)  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.  This file should be in /home/adev/scaler for CODA 2.x setup.  

V.  Online Codes

 There are three 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), and 3) "hana".    To run dhist, simply type "dhist".  Though it should run anywhere, lets be definate: Log onto adaqh2 as adaq account 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

The online code called ``hana'' for checking the trigger is documented at   www.jlab.org/~rom/CheckingTrigger.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.