Below is a beam test plan for the PePPO annihilation counters.

ATLIS task #

https://cebaf.jlab.org/atlis/task/12074

JLab Wiki

https://positron.jlab.org/wiki/index.php/02222012_AnnihCntr_TestPlan

Accelerator Configuration

Accelerator Settings

beam energy	6.8 MeV
Beam type:	Electron
I_average:	0.3 nA
I_peak:	0.05[math] \mu[/math] A 0.006 duty factor
pulse width:	10 [math]\mu[/math]s
Rate:	60 Hz
PEPPO Spectrometer:	151.3 A

Observe Beam spot on ITV5D03A

Record an image of the beam spot size seen by the ChroMox viewscreen.

https://cebaf.jlab.org/elog/entry/1666618

Turn on Annihilation Counters

Step 1: Bring up MEDM slow controls screen (skip if PEPPO screen is already up)

Skip this step if MEDM is already available on your screen

Otherwise

ssh username@opsmdaq1

type the following command to start the MEDM screen

opsmenu

a screen appears with one button called "OPS Menu"

a submenu appears when you click on that button.

Select the "EDM" menu.

The Monticello GUI will appear

click on the Injector screen (left button") and select "PePPO overview" from the menu

Look for a menu item with the title associated with the annihilation counters

Step2: Set HV to Detectors

Set the value of the HV dac listed in the table below (0-5) which corresponds to the desired HV for Detector #1 or #2.

For example: If you set HV dac value to 2.4 for detector #1 then its HV will be set to 960 which should bring the 511 peak into range for the FADC.

	Signal channel	HV dac	HV (V)
Detectors #1	A1	2.4	960
Detectors #2	A2	3.0	1200

There is on/off button for HV PS on the control menu. After setting the above HV dac values, you need to turn it on, then you will notice the display column change with a read back value.

Set FADC threshold

Login to the IOC for the FADC (on 11/7/2011 the command "telnet iocmdaq1" worked)

When logged in to the ROC for the FADC you use the function below to set the FADC threshold

faSetThreshold(FA_SLOT,fADC_Threshold,0xffff);

On Aug of 2011 the following values worked

fADC_Theshold = 200

FA_SLOT=?

reminder: the processing mode function has the following syntax

faSetProcMode(FA_SLOT,1,280,250,3,6,1,0);

Setup CODA run configuration

If CODA is running select the run configuration

"Annih_Sample"

If CODA isn't running

go to the CODA Runcontrol GUI and check that the configuration is using "FADC"

if coda isn't running try use the information below to start it

Start CODA

Take Data

Log book entry

https://cebaf.jlab.org/elog/entry/1666585

https://cebaf.jlab.org/elog/entry/1666627

Target in

Check that the ChroMox target is in by observing a beam spot

Then start the DAQ and run for 15 minutes

Run#

run mode

Beam

Target

Trig at

Run Duration

VME discriminator Threshold (mV)

HV1 (setting/V)

HV2 (setting/V)

PL (setting/ns)

PTW (setting/ns)

Det1 connected to

Det2 connected to

Spectrum

511 / Beam Current

2734

sample

on

In

det1

130 s

20

2.4/960

3/1200

280/1120

250/1000

FADC Chan#14

Not connected

300 px

4.9 /0.3 nA = 16.33 Hz/nA

2735

sample

on

In

det1

69 s

20

2.4/960

3/1200

280/1120

250/1000

FADC Chan#14

Not connected

4.246 /0.3 nA = 14.15 Hz/nA

2736

sample

on

In

det1

73 s

50

2.4/960

3/1200

280/1120

250/1000

FADC Chan#14

Not connected

7.507 / 0.3 nA = 25.023 Hz/nA

http://opweb.acc.jlab.org/CSUEApps/elog/entry/1666627

We took data for the annihilation counter detectors with their own configuratio n and no fadc trheshold, but Threshold in the VME discriminator of 20mV. The detector N.1 is plugged in: fadc channel CH 14 TDC channel CH 9

/data/annihilation/

We have 2 differnt runs, one with the beam in the target of the annilitation cr oss insertet and one with no beam in the beam line.

Target out

Watch the ChroMox viewer as you move it out of position, so there is no longer a target in place.

Start a CODA run for 15 minutes

Run#

run mode

Beam

Target

Trig at

Run Duration

VME discriminator Threshold (mV)

HV1 (setting/V)

HV2 (setting/V)

PL (setting/ns)

PTW (setting/ns)

Det1 connected to

Det2 connected to

pulses

2737

sample

off

Out

det1

466 s

20

2.4/960

3/1200

280/1120

250/1000

FADC Chan#14

Not connected

Data Analysis

Overlay of runs.

August Det #1 measurements with a source suggest a calibration of Aug 2011 Annihilation Counter Measurements.

510.998910 keV/39652.6 integrated channel

Just plot either run 2734 or 2735 and label with the threshold value of 20 mV

Replace run 2736 label with threshold 50 mV label

Replace run 2737 label with 20 mV Background label.

Replace titles with a Date of the experiment. Label axes "MeV and Hz"

set number size 0.4 and letter sizes 0.6

Dead time correction

Find dead time.

Scaler:__________|-|__|-|__|-|__|-|__|-|___ 5 pulses

FADC scaler: ____________|-|_____________ 1 pulse

(5-1)/5=80% dead time.

If I have 80% dead time, I should multiply my counts by 1/(1-80%)=5.

Erica's dead time calculation:

Dead time = L1A/L1

Erica Said
L1 or Level 1 is the incoming trigger. In this case is the detector signal (or the AND, when there is a coincidende, of the 2 detector signals) used as a start.
The L1A or Level 1 Accept is the signal coming from the VME CPU that tells to the rest of the electronics that it can read and accept trigger, because it is not busy processing the previous data.

My understand is: L1 is incoming triggers. L1A are those L1 that is accepeted (or executed).

So, L1A/L1 should be the live time.

mutiply the beam on data by a factor of 6 and leave the beam off data alone

Run#	run mode	Beam	Target	Run Duration	L1A	L1	Dead time (L1A/L1)	Connected to	Spectrum	511 Rate (Hz)
2734	sample	on	In	130 s	613861	20688978	0.0296709195	FADC Chan#14		165.4
2735	sample	on	In	69 s	318135	11173904	0.0284712487	FADC Chan#14		149.1
2736	sample	on	In	73 s	423650	3961157	0.106951075	FADC Chan#14		70.19
2737	sample	off	Out	466 s	525684	3115913	0.16870946	FADC Chan#14