GUIDE TO DATA TAKING IN HALL A

Bob Michaels,     v2.7,     Sept 19, 2002

pager: (757)-584-7410,    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, atrig, and a-onl. The run coordinators should know the passwords.  

Where to Run Online Software in Hall A Counting Room

Code	Computer	Public  Account
CODA  (runcontrol)	adaql2	a-onl
ESPACE	adaql1, 3 or 4 (not l2)	adaq
trigsetup	adaql1 or 2 (Linux)	atrig
HRS dataspy and dhist	adaqs2 (SunOS)	adaq
xscaler (Sun version)	adaqs3	adaq
xscaler++ (Linux version)	adaql1, l2, ep, or cp (Linux)	adaq

Computers:   adaqs1 will be the Compton DAQ computer. It should be avoided, e.g. the paths are different. Typically   adaql2 is used for spectrometer DAQ, adaqcp is for Parity or Compton, adaqep for eP energy measurement DAQ, adaqs3 for Moller DAQ.   adaqh2 is the lone remaining HP-UX which has been moved to 2nd floor counting room and will not be replaced when it dies.   adaql1, l3, l4 is for running online ESPACE analysis, and other analysis codes, but any computer 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. adaqlr3 is a Linux PC that remained in counting room since RCS experiment. Use it as an X-term. Some PCs are also installed in 2nd floor cubicles. Priority for use goes to running experiments.

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". 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 may be found in 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 FAQ's about deadtime,   plus electronics 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.

Overview of High Resolution Spectrometer (HRS) 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. Thus, the main trigger requires four PMTs.  The coincidence between spectrometers 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 are T2 and T4, which requires 2 out of 3 from among the S1, S2, and S0 detectors (i.e. the "or" of S1 is used, etc). Actually the definition of T2 and T4 has changed several times (ask me for details); what I described is for e00007 and beyond.   These "loose" or "majority logic" triggers allows to measure the efficiency of the main trigger. The experiment should always keep about 5 - 10 Hz of these loose triggers. In e00007 there is also a 30 Hz T9 which cannot be prescaled. The purpose is to measure at each helicity flip.

Downloading the trigger:   It is forseen that the only change between kinematic settings that affect the trigger are delays that change with the momentum and particle ID.   Of course, if you only care about single arm triggers, you may use the default settings.  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).  

V.  Scalers and Scaler Display

As of Jan 2002, there are two versions of ``xscaler'', the GUI that displays scaler data online. The old version, which still works for the two HRS, runs on SunOS. A new version which works for all spectrometers (including RCS calo) runs on Linux.

SunOS version:   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 e00007.)  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.

New Linux version:   Login to adaq account on a Linux machine, preferably adaql1, l2, ep, or cp, and 'cd ~adaq/rcs/xscaler' and type './xscaler' there (with dot and slash). Answer the obvious question about which spectrometer system.

  The ``old'' asynchronous readout of scalers are event type 140, which are injected into the datastream asynchronously every few seconds.   A ``new'' readout exists, in which the data are read every synch event (100 events) if DAQ is in buffered mode and every 200 events regardless of mode. This readout also contains helicity and timestamp info necessary for G0 mode. Details are at www.jlab.org/~rom/scaler_roc10.html for the new readout, and for the G0 helicity scheme see www.jlab.org/~rom/g0helicity.html.

 Scalers are also read and injected into the datastream 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 ~a-onl/scaler.

VI.  Online   Codes   for   Spectrometer

 Two codes of interest for doing online diagnostics of raw data, in addition to using ESPACE are:  (1) dataspy, and (2) dhist.      To run the HRS dhist, simply type "dhist" on a SunOS computer like adaqs2 or s3 from the adaq account.   You will see a reminder that you have to go to the proper directory and type "./dhist" there. Just do it.  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 obtain data in real-time while not causing deadtime.