Cologne DAQ for Miniball at CERN

Transcription

1 Cologne DAQ for Miniball at CERN Contents 1 Overview 3 2 Getting started 3 3 Working on the power PC 3 4 Configuration 4 5 Naming conventions 4 6 Booting 4 7 Setting up 5 8 Viewing untriggered traces 6 9 Examining the DGF parameters 7 10 Setting and getting the paramters from the setup files 7 11 Sending parameters directly to the DGFs 8 12 Setting the offsets 8 13 Acquiring MCA spectra 9 14 Viewing spectra cne tv mca viewer Fitting 60 Co spectra Example Scanning τ Old method - with 60 Co only New method - with any strong sources Performing the gain matching with 60 Co Example Switching back to Marabou Merging parameters Old method New method Nigel Warr June

2 20 Viewing root spectra with tv or cne Troubleshooting 17 2

3 1 Overview The Cologne DAQ was originally written for experiments using DGFs in Cologne and was designed to use the Jülich crate controllers. However, later it was necessary to support Jorway controllers, and in the end I added support for the CC32. However, this CC32 support is very slow, because it was done in a quick and dirty manner at CERN, rather than properly. So in order to improve on this, I ported most of the programs to the power PC. However, there are several shortcomings in the power PC. It is not possible to run graphical programs over a firewall, because the connection to the power PC is via rsh, not ssh, so it doesn t transport X windows. For this reason, I have split the system into two halves, which communicate via files on disk. On the power PC side, we have all the programs which communicate directly with the CAMAC crate (mb boot dgf, mb setup dgf, etc.) and on the other side we have the graphical programs (mb dgf config, scope etc.) A few programs work on both platforms, and for convenience, I have set up a mb ppc remote script which is used together with symbolic links to call the program with the same name as the symbolic link, from the main DAQ computer, so that it runs on the power PC via rsh. 2 Getting started Make sure no Marabou processes are running on the power PC Actually, it still seems to work if m esone serv, m util or m msg log are running, as long as you don t actually use programs like C analyze or DGFControl. 3 Working on the power PC In order to work on the power PC, you must log in and start the bash shell. The software only works with bash at the moment. rsh ppc-0 bash You should not need a password to log into the power PC. If you get a password prompt, check the /mbdata/miniball/.rhosts file has an entry minidaq miniball and that /usr/diskless/lynx/rio2 2.5/etc/hosts has the entry minidaq MINIDAQ. Note that, as far as the power PC is concerned, the main Miniball DAQ computer is called minidaq (and not minidaq.cern.ch or pcepuis20.cern.ch or whatever) no matter where it is installed. That name is valid on the private network and should not be changed. Nor should it have a domain name, since even if the first ethernet card of the DAQ computer is on, say, the CERN network, the power PC is NOT on the cern network and should NOT have a.cern.ch name. Unfortunately, sometimes Marabou gets this wrong! 3

4 4 Configuration Once you have started bash, the file /mbdata/miniball/.bashrc is called, which sources the file /home/miniball/nigel/.mb to define some environment variables. One is MB CONFIG DIR which points to the directory where the configuration is. The only important file is source.conf which contains one line for each DGF channel being used (including DGFs which are plugged in, but will not actually be used). The software doesn t read any of the other files in that directory. To make life simpler, there are some files like triples.inp which define the same information in a simpler form. Then you run the command mb generate source < source.inp > source.conf to generate the source.conf files from these files. Setting the r value (i.e. the distance from target to detector) to is equivalent to saying the detector is not connected, but the DGF is still there and has to be programmed. It makes some operations faster if the unused detectors are removed in this way. Edit $MB CONFIG DIR/source.conf 5 Naming conventions The crates are counted from zero (unlike Marabou which counts from one). The labels on the crates correspond to those used by Marabou, not those used by the Cologne DAQ, so you have to always subtract one from the label. The channels are named with cluster number, detector letter and segment number, where the core is treated as segment zero. e.g. 14A0 is the core of detector A of cluster 14 and 16B3 is segment 3 from detector B of cluster Booting After the crate has been powered up, or if the DSP of one of the DGFs crashes, you have to boot the DGFs. The program to do this is mb boot dgf. If executed without any parameters, it boots all the DGFs referred to in source.conf. Alternately, mb boot dgf 0 boots just those in crate 0 (Remember we count from zero!). Note that if you boot with Marabou, you don t have to boot with the Cologne DAQ and vice versa, but then you must take care that both systems are using the same FPGA and DSP codes. The environment variables: SYSFPGAFILE, FIPFPGAFILE D, FIPFPGAFILE E, DSPFILE, DSPPARNAMEFILE point to the system FPGA, the Fippi FPGA (for Rev. D DGFs), the Fippi FPGA (for Rev. E DGFs), the DSP code and the DSP variable names files, respectively. They are, however, just symbolic links to the real files. This program is executed on the power PC. There is a symbolic link to mb ppc remote on the DAQ computer, which will execute mb boot dgf on the 4

5 power PC via remote shell for you. This is, however, slightly slower than just logging into the power PC and runing mb boot dgf from there. On the power PC mb boot dgf 7 Setting up Once the DGFs are loaded, you have to load up the DPS parameters. The Cologne DAQ stores a set of parameter files (in ASCII) in a directory pointed to by the environment variable DGF SETUPS DIR. They are named according to cluster, detector letter and segment number. e.g. dgf config 14A0.setup (for the core of 14A). Figure 1: The DGF config program. Note that this program only edits the config files on disk and doesn t change anything on the DGF. However, mb sample is a special case, because it monitors the files on disk and changes the parameters on the DGF if the disk file changes. The GUI program mb dgf config can be used to edit these files. Click on the appropriate name. Click on load. Change what you want. Then click on save. 5

6 This only changes the file, not the values in the DGF. This program must be run on the DAQ computer. To load the values onto the DGF use mb setup dgf. Like the boot program, if you run mb setup dgf without any arguments, it sets up everything. Otherwise, you can specify the crate number (counting from zero). This program should be run on the power PC, but there is a link on the DAQ computer to run it on the power PC via rsh. On the Power PC: mb setup dgf On the DAQ computer: mb dgf config 8 Viewing untriggered traces When ramping up the high voltage, or generally to check out a channel, it is useful to look at untriggered traces. The Cologne DAQ has a sampling program to do this and an oscilloscope program to view the resulting samples in real time. This part has changed quite a bit in the new version of the code. Previously, the user started mb sample on the DAQ computer and it started the scope program which does the graphical visualisation of the traces. Now, the sampling program has been moved onto the power PC (which is much faster), but the scope program must still run on the DAQ computer, so the user has to start both programs. To start the scope program, run start scope on the DAQ computer. To stop it run stop scope. Note, that it is not enough just to kill the windows, since scope creates 16 windows, but only those actually used are revealed. The scope program monitors files in the directory pointed to by the environment variable SCOPE DIR. Normally the scope windows are opened in rows of three windows. This can be changed by calling start scope with the -n switch. On the power PC run the mb sample program. You must specify the list of channels to look at. e.g. mb sample 14A0 16A0 17A0. This tells scope to open one window (up to a maximum of 16 windows) for each channel, where the signals are displayed. Several traces are shown in different colours in each window (from the same channel) one after the other. The? symbol can be used as a wild card e.g. mb sample 16C? to show all seven channels from 16C. Normally, the scope windows are set to autoscale, but with the switch -y it is possible to fix the y scale. e.g. mb sample -y A0. I usually use mb sample -y A? to look at all of 17A. 6

7 Unlike all the other programs in the Cologne DAQ, for the mb sample program it isn t necessary to run mb setup dgf first, because mb sample continuously watches the setup files for the channel it is sampling and if the file is changed, it applies the new values to the DGF at once. In this way, you can make modifications using mb dgf config and as soon as you click on save, the file is modified, mb sample notices this, and changes the values on the DGF and you see the result in real time (albeit a bit slowly). You can use this method to set the offsets by hand, but its main purpose is for monitoring while ramping up the voltage. On the DAQ computer: start scope 3 On the power PC: mb sample -y A? 9 Examining the DGF parameters The program mb showdgf is used to look at the contents of the DGF parameter memory. It is called with two arguments: the crate (starting from zero) and slot number of the DGF you are interested in. The results go to standard output. It gives the contents of the CSR and ICSR registers and the complete list of DGF variables and their contents. Also at the end it gives the conversions of parameters like PREAMPTAU, TRACKDAC into useful units (i.e. µs in the case of τ and Volts in the case of the offset). This program should be run on the power PC, but there is a link on the DAQ computer to run rsh for you. On the power PC: mb showdgf Setting and getting the paramters from the setup files The programs mb set param and mb get param are used to set or get the parameters like GAIN, TAU, OFFSET from the setup files. e.g. mb set param TAU 50.3 $DGF SETUPS DIR/dgf config 14A0.setup is used to set the tau value of 14A0 to 50.3 µs. 7

8 and mb get param TAU $DGF SETUPS DIR/dgf config 14A0.setup is used to get the tau value (which is written to standard output). Note that both these commands only work with the setup files, not the values in the DGF. These programs work on both the power PC and the DAQ computer. Since they only manipulate files, they are fastest on the DAQ computer. Don t forget that apart from mb sample, none of the other programs look at these files, so you have to run mb setup dgf to transfer the parameters to the DGFs. 11 Sending parameters directly to the DGFs The program mb send par which is called with crate (starting from zero) and slot number of the DGF, name of the parameter and the value, sets this value in the DGF directly without using the setup files at all. This is useful for setting parameters which are not normally accessible from the setup files. In particular, the Cologne DAQ only lets you set the polarity in CHANC- SRA0... 3, but Marabou needs all the bits set correctly. So you have to use mb send par to fix this parameter. This program should run on the power PC. Again there is a link on the DAQ computer to make life easy. On the power PC: mb send par 0 3 CHANCSRA0 0x0a75 mb send par 0 3 CHANCSRA1 0x024d mb send par 0 3 CHANCSRA2 0x024d 12 Setting the offsets As well as using mb sample and mb dgf config to set the offsets by hand, there is a method to set them automatically. This is done with mb ramp dac. This command ramps the offsets of all the DGFs simultaneously to determine the optimal offset. It does not change the offsets. Instead it writes a command to standard output, which if executed modifies the setup files. So the procedure is: 8

9 On the power PC: mb ramp dac > tempfile On either computer: edit tempfile by hand to eliminate any spurious values bash tempfile 13 Acquiring MCA spectra The command mb mca acquires for 300 seconds on crate 0 after having done a test run of 2 seconds. You can turn off the test runs with the -t switch. The spectra are written into the directory pointed to by the environment variable HW HIST DIR and have names like CLU 14C3.spc. These are actually just links to spectra with names based on the DGF crate slot and subaddress number. The spectra are in radware gf2 format. This program should run on the power PC, but a link has been set up to let you run it via rsh from the DAQ computer. On the power PC mb mca -t Viewing spectra The spectra are written in the Radware format. This has a header (36 bytes) and then little endian 4-byte floating point data (32768 channels). These programs must be run on the DAQ computer cne I used to use the program cne to view the spectra. e.g. cne CLU 14C?.spc (the question mark in the filename is a wildcard - i.e. all the segments and the core). Hitting? in cne gives the list of keypress commands. Q to quit. Z, click left, click right to zoom in. F, P, click left, click right to fit a peak tv Another program which can be used is the Cologne program tv. Start it with tv and then enter commands into the command window (see the man page for tv). 9

10 Figure 2: The CNE main window Figure 3: The tv graphics window, showing the kev peak in 60 Co. Each spectrum is for a different τ value. The rightmost peak is for 44 µs and the left one is 56µs. Note the colours have been inverted in this figure. In tv on the DAQ computer spectrum get CLU 23A*.spc press escape in the graphics window 10 use space to mark left and right markers and E to expand window hide spectrum-names to hide the key.

11 14.3 mca viewer The program mca viewer is an alternative to cne which was written for the student practical classes in Cologne. I tend to use it now instead of cne. 15 Fitting 60 Co spectra The program fit 60Co is used to fit a 60 Co spectrum. It takes the spectrum name as an argument on the command line and writes the output to standard output. This program must be used on the DAQ computer. I often use commands like: fit_60co CLU_14A0.spc grep FWHM1\(keV\) to get just the resolution at 1.3 MeV from that spectrum. (Note the backslashes before the brackets which are needed by the shell) Example The command: fit_60co $HW_HIST_DIR/CLU_14A0.spc gives an output like: Spectrum: /home/miniball/nigel/hw_hist/clu_14a0.spc Limits0: AREA0: 1.48e e+03 POSITION0: 8.8e SIGMA0: BCK_OFF0: BCK_SLOPE0: BCK_QUAD0: TAIL10: TAIL20: Chisqr0: Position0(chn): / chn Position0(keV): / kev Area0: / Sigma0(chn): / chn Sigma0(keV): / kev FWHM0(chn): / chn FWHM0(keV): / kev Limits1: AREA1: 1.33e e+03 POSITION1: 1e SIGMA1: BCK_OFF1:

12 BCK_SLOPE1: BCK_QUAD1: -3e TAIL11: TAIL21: Chisqr1: Position1(chn): / chn Position1(keV): / kev Area1: / Sigma1(chn): / chn Sigma1(keV): / kev FWHM1(chn): / chn FWHM1(keV): / kev Ratio: Calibration: kev From this we see that the 1173 kev peak was in channel and the kev peak in channel giving us a gain of kev/channel. The first peak has an area of and the latter of counts. The resolution is 2.46 kev at 1.3 MeV. 16 Scanning τ The leading flank of a Ge signal is determined by the interaction position and the electron and hole mobilities, but the trailing flank is determined by the preamplifier. Most preamplifiers used for Ge detectors have a resistive feedback with a characteristic time, which is nominally 50 µs. However, variations of 10 % about this nominal value from one preamp to another is normal. The DGF uses a trapezoidal filter, i.e. one which gives a trapezoidal response to an infinite step function. The effect of the resistive feedback, is to make the flat top of the trapezoid slope downwards. In order to calculate the energy correctly, the DGF has to take this into account and to do this it needs to know the τ value for each detector precisely. In principle, we could sample τ traces and fit them to try and obtain some τ value, but in practise this method doesn t work very well. Since the only reason we want to determine τ in the first place is to get the best possible peak shape (i.e. FWHM and also tails), the best way is to vary τ and observe the effect on the resolution. We could do this by taking an MCA spectrum at a given τ for a while, then changing τ and measuring a new spectrum. However, we need quite a lot of statistics, before we can decide, but if we acquire for long times at each τ value we can have systematic effects (e.g. due to the LN?2 filling cycle). So instead, we acquire for 10 seconds for each of a set of τ values and then write all the spectra. Then we acquire some more and add the spectra together. In this way, systematic effects are evened out, and we can also see the spectra as they grow. 12

13 16.1 Old method - with 60 Co only This is done by the program mb scan tau which runs on the power PC. In principle we need one spectrum for each τ for each channel, so if we want to scan about 30 τ values for all 168 channels of Miniball, this would be nearly a gigabyte of spectra, which is not very practical, so we only scan one cluster at a time. In any case, we can t usually get a strong enough source to be able to scan more than one cluster at a time. The procedure is to hang a strong 60 Co source directly in front of one cluster, right up as close to the centre of the end cap as possible. Set the radius in $MB CONFIG DIR/source.conf to 100 for all channels except those for that cluster. Make sure the baseline is correct for each channel of that cluster (note that the base lines are lowered by a high count rate, so it may be necessary to change the offsets). Then run mb scan tau with a list of τ values to scan. On the DAQ computer Set the radius in source.conf for all channels to be scanned < 100 and those not to be scanned 100. On the power PC mb scan tau This will generate a load of spectra in $HW HIST DIR with names beginning with tauscan, then the name of the channels then the tau value. You can view these with tv or cne or you can fit them with fit 60Co. Try to find the value of τ for each channel, which gives the best combination of FWHM and peak shape. Then use mb dgf config to set this value. Don t forget to run mb setup dgf afterwards to actually write the values to the DGF. Note that the segments are a lot less sensitive to τ. If the variation in the FWHM as a function of τ is almost flat at a high count rate, don t worry about it. This simply means that it is not very sensitive to τ. If, however, the core shows a flat response, it probably means the count rate is too low New method - with any strong sources When Wolfgang Hennig from Xia came to Cologne, he told us that there is another way to optimise τ. It relies on the fact that a bad τ value leads to samples being included in the baseline determination, which should not, so the baseline broadens. In other words, the narrowest, most symmetric baseline corresponds 13

14 to the optimum τ value. So I wrote mb scan tau by baseline which has the same syntax as mb scan tau. In other words you give it a load of τ values. It takes baseline samples for each τ and histograms them. You need to have a high count rate for the scan to work well, but unlike the old method, it doesn t matter what energy the γ rays have as long as they appear in the spectrum. So you can use a mixture of different souces. Then it determines the position, skew and width of the baseline for each τ value and writes a log file for each active channel. If you plot the width as a function of τ you get some sort of parabola with a minimum. The root-based program analyse tauscan reads the histograms generated by mb scan tau by baseline and plots them. It also determines the optimal value of τ and generates a bash script called set tau.sh, which, if sourced, will set the τ values to the optimum it has determined. 17 Performing the gain matching with 60 Co The program mb gain match is designed to help set the gains of the DGFs so that the peaks are all in the same place. First acquire 60Co spectra with mb mca and then use mb gain match to determine the appropriate gain to put the kev peak at a given channel. You provide it with the channel where you want the keV peak to be and the name of the channel(s) (e.g. mb gain match A0 17B0 ). It then fits the spectrum for those channels and calculates what gain the DGF should have in order to put the 1.3 MeV 60 Co line at that channel (10000 in this case). Note that it reads the old gain from the setup files and the spectrum from the directory pointed to by HW HISTS DIR, and that it is up to you to ensure that the spectrum was actually acquired with this value. In other words, prior to calling mb gain match you have to do a mb setup dgf to put the paramters onto the DGF and then acquire a spectrum with mb mca on the appropriate channel. Note, however, that the DGF isn t all that linear, so you may have to make several iterations. Furthermore, changing the gain influences the offset, so you have to be careful, you don t drive the offset off the scale, so that either the peak is lost, or that there is no data at all. I recommend changing in small steps and possibly running mb ramp dac in between iterations. This program should be run on the DAQ computer. 14

15 On the power PC Use mb mca to acquire spectra On the DAQ computer mb gain match A0 17B0 > tempfile Edit tempfile to remove spurious values bash tempfile On the power PC mb setup dgf 17.1 Example The example above produces an output like: mb_set_param GAIN /home/miniball/nigel/config/dgf_setups/dgf_config_16a0.setup mb_set_param GAIN /home/miniball/nigel/config/dgf_setups/dgf_config_17b0.setup Executing those two commands generated in the output will change the gains on those two DGFs, so that after running mb setup dgf on the power PC, the gain should be such that the 1.3 MeV line should end up at channel Switching back to Marabou On the power PC kill all of the processes of the Cologne DAQ On the DAQ computer DGFControl Restart ESONE server Reload DGFs Connect Restore parameters from file 15

16 19 Merging parameters Normally, we will want to determine parameters using the Cologne system and then enter them into Marabou. We could do this by hand, but this is quite tedious. A better way is to set up the DGFs with the Cologne system Old method We set up with the Cologne system, then dump all the parameters to a file, switch to Marabou and then use the Cologne system to modify just those parameters, which we want to change. We can use the script mb dump params to dump the parameters. It simply calls mb showdgf for each DGF into files with names like HW HIST DIR/dgf parameters 0 3.dat (for crate 0, slot 3). We can use another script mb upload params to upload the parameters back to the DGF again. This script takes a list of DGF parameters on the command line, and it will search for the appropriate values in the parameter files and generate mb send par commands. You should send the output of this script to a file, edit the file to remove any values you don t want and then execute the resulting file with bash. On the power PC mb dump params On the DAQ computer Switch to Marabou, rebooting and restoring parameters from file On the power PC mb upload params PREAMPTAU TRACK- DAC GAINDAC > tempfile Edit tempfile bash tempfile On the DAQ computer System Connect in Marabou Save parameters in Marabou 16

17 19.2 New method We set up with the Cologne system, then run mb to marabou which creates a /mbdata/miniball/dgfsettings/nigel4 directory and generates marabou settings files in it. You can then start DGFControl and load these settings and save them to the desired directory. 20 Viewing root spectra with tv or cne If you want to use tv or cne to view the spectra in a root file, you can use the program root gf2 on the DAQ computer. It takes the name of the root file as a parameter and generates gf2 format spectra, which can be viewed with cne or tv. The spectrum names are those from the root file (i.e. what you see with.ls in root) with the addition of the extension.spe and they are written to the current working directory. This is useful if you are working over a slow connection as tv and cne are much less graphics-intensive than HistPresent. On the DAQ computer In Marabou, acquire MCA spectra, creating a file mca.root root gf2 mca.root 21 Troubleshooting Sometimes things hang and not even a control C can get out of the hang. Usually then, the power PC has crashed. In that case, kill any programs that are running with kill -9 and reboot the power PC (i.e. toggle the reset switch on the front of the VME module). Wait for it to boot completely (the crate shows SYS FAIL when the power PC is not running). Another problem, which has occurred in the past, is invalid date in the upper 16 bits of a CAMAC read. The CAMAC bus is intrinsically 24 bit (i.e. there are only 24 data lines), but the CC32 sends two 16 bit words to the VC32 for each cycle, making a 32 bit word on the VME side. Clearly the top 8 bits of the 32-bit word should be zero. When the error occured, the top 8 bits were the same as bits Reseting the power PC did not help, but power cycling the VME crate fixed the problem. If you get a message unable to find parameter CFD2FIFO0 on running mb sample, this probably means that you booted in Marabou (which uses an older version of the DGF code) and didn t boot again with the Cologne system. 17