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Some UCESB zero-suppressed multi hit documentation [message #18949] Thu, 28 January 2016 14:05
Ralf Plag is currently offline  Ralf Plag
Messages: 25
Registered: September 2015
continuous participant
From: *gsi.de
For electronics that produces multi hit data, here is how to handle it through ucesb:

-----------------------------------------------------

In the ucesb .spec file:

Declaration (here for 16 energy channels):
MEMBER(DATA32 E[16] ZERO_SUPPRESS_MULTI(10));

Filling (as usual):
ENCODE(E[channel_id],(value=data));

Mapping:
It is necessary to declare the output variable as multi hit type as well:

SIGNAL(ZERO_SUPPRESS_MULTI(10): raw_level_output_variable);


The actual mapping then goes as usual.
Example: Mapping febex data to the PSPX01:

// Declaration of output variable PSPX01:
SIGNAL(ZERO_SUPPRESS_MULTI(10): PSPX01_01);

// Mapping of channels
SIGNAL(PSPX01_01,  psp_febex.febex2.E[14], DATA32);
SIGNAL(PSPX01_02,  psp_febex.febex2.E[15], DATA32);
SIGNAL(PSPX01_03,  psp_febex.febex2.E[12], DATA32);
[...]

-----------------------------------------------------
Reading the data
-----------------------------------------------------

In the ucesb output, either via root TTree or struct_writer you'll find the following variables (sticking to the PSPX01 example):

PSPX1: size of array PSPX1v
PSPX1v: array of size PSPX1 holding the actual data (here energy values)
The order in the v-array is: all hits of first channel with data, all hits of second channel with data, ...

PSPX1M: number of channels that have data
PSPX1MI: array of size PSPX1M holding the channel numbers of each channel with data
PSPX1ME: array of size PSPX1M providing the index in array PSPX1v of the first element of the next channel (or more generally: last element of current channel + 1)

--

Example data:
Channel 4 has two hits: E=430 and E=485
Channel 9 has three hits: E=938, E=923, E=967

PSPX1 = 5
PSPX1v = 430, 485, 938, 923, 967

PSPX1M = 2
PSPX1MI= 4, 9
PSPX1ME= 2, 5

--

When reading the channels, the following pseudo code should work:

numChannels = PSPX1.M;
       
curChannelStart=0;  // index in v for first item of current channel

for (i=0; i<numChannels; i++)
{
    channel=PSPX1.MI[i]; // channel number: 1..max_channel
    
    // get index in v for first item of next channel:
    nextChannelStart=PSPX1.ME[i];
           
    // read all hits of channel 'channel'
    for (j=curChannelStart; j < nextChannelStart; j++)
    {
        energy=PSPX1.v[j];
        // do something with energy
    }

    curChannelStart=nextChannelStart;
} 

[Updated on: Mon, 01 February 2016 08:48] by Moderator

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