Difference between revisions of "Forward Drift Chamber Shift"

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The Forward Drift Chamber (FDC)  system consists
 
The Forward Drift Chamber (FDC)  system consists
−
of four identical packages, each having six chambers (cells).
+
of four identical packages (named FDC1 to FDC4), each having six chambers or cells (named CELL1 to CELL6).
−
These are planar drift chambers with both wire and cathode strips being readout,
+
These are planar drift chambers with both anode wires and cathode strips being readout,
 
in total 12,672 channels.
 
in total 12,672 channels.
  
 
The cells within a package
 
The cells within a package
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have independent gas volumes, but are separated with a flexible mylar membrane
+
have independent gas volumes, but are separated with a flexible mylar membrane.
−
and therefore <font color=red> the pressure difference between neighboring cells should never exceed 30~Pa </font> and should normally be less than 5~Pa.
+
Therefore, <font color=red> the pressure difference between neighboring cells should never exceed 30 Pa </font> and should normally be less than 5 Pa. Note that
 +
the interlock should safeguard against excessive differential pressure.
 
   
 
   
−
Positive (up to 2200V) and negative (up to 500V) HV is applied on the
+
Positive (up to 2200 V) and negative (up to 500 V) HV is applied on the
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sense and field wires respectively with <font color=red> dark currents not exceeding 3 microA per HV channel</font> .
+
sense and field wires respectively with <font color=red> currents not exceeding 3 microA per HV channel</font> .
  
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The detector (including cables) emits a total power of about 1500~Watt,
+
The detector (including cables) emits a total power of about 1500 Watt,
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of which about 900~Watt inside the magnet,
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of which about 900 Watt inside the magnet,
 
due to the LV applied on the detector pre-amplifieres.
 
due to the LV applied on the detector pre-amplifieres.
 
A cooling system using Fluorinert is used to keep the temperature on the
 
A cooling system using Fluorinert is used to keep the temperature on the
 
pre-amplifiers within the permissible limits. <font color=red> The LV system should never be turned ON if the cooling system doesn't work </font>.  
 
pre-amplifiers within the permissible limits. <font color=red> The LV system should never be turned ON if the cooling system doesn't work </font>.  
 +
The interlock should safeguard against this condition.
  
 
== Routine operation==
 
== Routine operation==
  
−
The most important task for the shift workers is to monitor the parameters (using GUIs) of the following FDC related subsystems: High Voltage, Low Voltage (including thresholds), Gas system, and the Cooling system. A description of how to bring up the corresponding GUI screens and how to operate them can be found in [[Slow Controls Shift| Section Slow Controls]]. The HV and LV subsystems, as well as and the Gas and Cooling systems have common GUIs. The GUIs are designed to show green color if all the parameters in a certain subsystem/subgroup are within the limits. If any of the parameters is out of limits the background for the corresponding subsystem/subgroup will turn red. Examples of the GUIs are shown below:
+
[[Image:FDC_HV_LV_GUI.png | thumb | 400px | Fig. 1. FDC HV, LV GUI panel. ]]
  
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[[Image:BCAL_environmental_sensors.png | thumb | 400px | Fig. 1. Environmental sensors for the BCAL. The red ovals highlight the information provided to the user, available for the upstream and downstream ends independently.  
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[[Image:FDC_GAS_system_screen.jpg | thumb | 400px | FDC & CDC gas panel including information about the colling systems. Fig. 2. ]]
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This includes the forty-eight temperature readings of each RTD on the cooling plates, which are in thermal contact with the back of the MPPC sensors, the nitrogen flow, and the four
+
−
measurements of temperature, humidity and dew point  of the gaseous atmosphere of the readout electronics.]]
+
  
−
 
+
The most important task for the shift workers is to monitor the parameters (using GUIs) and report any changes from the normal operation for the following FDC related subsystems: High Voltage, Low Voltage (including thresholds), Gas system, and the Cooling system.  A description of how to bring up the corresponding GUI screens and how to operate them can be found in [[Slow Controls Shift| Section Slow Controls]]. The HV and LV subsystems, as well as the Gas and Cooling systems have common GUIs. The GUIs are designed to show green color if all the parameters in a certain subsystem/subgroup are within the limits. If any of the parameters is out of limits the background for the corresponding subsystem/subgroup will turn red. Examples of the GUIs are shown in Figs. 1 and 2.
  
−
<!--
+
The shift workers are allowed, using the GUI, to turn ON and OFF all the HV and LV (including thresholds) systems, as well as parts of them or the individual channels. Instructions how to do this are given in [[Slow Controls Shift| Section Slow Controls]], but the general rule is either to bring the pop-up menu with left click on the group title (like "ALL HV", or "FDC 1") or to click on the individual channel knob (the knob title shows the action to be taken after pressing it). For example, in case a HV channel trips, one should press the corresponding channel knob once (acknowledging the trip) and then again to turn it on. The corresponding voltage parameters, like rump up/down rates, trip currents, set voltage values etc. cannot be changed by the shift workers. The Gas and cooling system GUI is only to be monitored by the shift workers; the parameters there cannot be changed.  
−
<font color=red> Operations beyond what was specified above shall only be performed by the system expert or under his/her direction </font>.
+
−
+
−
During routine operation the user will need to monitor the environmental conditions, which may affect BCAL performance, as well as turn the
+
−
system on and off. The following instructions are for non-experts during routine operation.<font color=red>  </font> If the expert directs an operation outside the  ones described here, a specific note must be entered into the log book.
+
  
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Control and monitoring of the system is accomplished using the Hall D graphical user interfaces (GUI) to EPICS [http://www.epics.org] [http://www.aps.anl.gov/epics]. A description of how to
+
In addition to the operations using GUIs, the shift workers should visually check the gas panel in the Hall using the camera "halldaxis7" with remote control installed there, and make sure all the bubblers operate normally. For instructions how to operate the camera, refer to [[Slow Controls Shift| Section Slow Controls]]. Once per shift the workers are supposed to record the manometer values and inspect other components in the gas room; see [[Gas System Shift| Section Gas System]].
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bring up the GUI screens can be found in [[Slow Controls Shift| Section Slow Controls]]. We briefly describe the use of these interfaces:
+
  
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===Checking the environment===
+
'''Operations beyond what is specified above shall only be performed by the system expert or under his/her direction'''.
  
 +
== Interlocks==
  
−
The temperature and humidity measurements of the BCAL can be displayed using the GUI shown in Fig. 1 . The controls and monitoring of environmental conditions is accomplished separately for the upstream and downstream readouts of the BCAL, which are connected to
+
To prevent damage of the equipment in situations explained in the first paragraph (where the corresponding critical parameter limits were highlighted with red) interlock systems are implemented. Hardware interlock is used to turn OFF the power of the LV crate in case the cooling system fails. Software (PLC based) interlock system  is implemented to turn off the gas supply if the pressure between any two neighboring cells exceeds 30 Pa. The HV and LV modules are set to immediately turn off the voltage if the current exceeds the corresponding limit. Setting the voltage channel back should be done only manually by the operator. We DO NOT use the automatic feature to keep the voltage (for a certain time) such that the current is at the limit.
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individual chillers and nitrogen gas flow lines. The coolant in the chiller (water for initial operations and later water and 20% propylene glycol for operation at 5 degrees C)
+
−
is circulated through input and output manifolds which feed two readout assemblies in series. The temperature of the chiller will be set prior to operation to maintain a
+
−
relatively constant temperature for the light sensors. The coolant flows through the cooling plate in each readout assembly, which is in thermal contact with the  
+
−
multi-pixel photon counters (MPPCs), and their temperature is recorded using RTDs attached to the plate. The temperatures are displayed in the figure and should normally
+
−
read within about 1 degree of each other. The space enclosed by the readout electronics is monitored using four temperature and humidity sensors, which determine the dew point,
+
−
on both the upstream and downstream. These measurements are displayed on the GUI to monitor the humidity level of the environment of the electronics.
+
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The space enclosed by the readout assembly is purged with dry nitrogen to avoid condensation, and the nitrogen flow rate is also indicated on the GUI.
+
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During routine operation, this GUI is for information only.
+
  
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===Voltage control===
+
== Expert personnel ==
−
[[Image:BCAL_voltages.png | thumb | 500px | Fig. 2.  Graphical interface for setting the voltages on the BCAL. Indicated are the pulldown menus for retrieving saved voltages from a file and the menus for turning the voltages on and off. ]]
+
  
−
The low voltage (LV) and bias voltages for the MPPC sensors can be set using the GUI show in Fig. 2. The voltages for normal operation are recorded in
+
The individuals responsible for the operation of the FDC are shown in the following table.
−
files, which can be restored using the button in the top middle of the screen. The LV and bias settings must be restored separately. Once the voltages have been restored to the
+
Problems with normal operation of the FDC should be referred to those individuals and any changes to their settings must be
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memory of the voltage supplies, the user may turn the voltages on by using the "All U Bias" and "All U LV" left buttons in the middle of the BCAL sketch. The voltages for the
+
approved by them. Additional experts may be trained by the system owner and their name and date added to this table.
−
downstream side are controlled using the buttons on the right.
+
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The voltage read back  and the current draw of each channel are histogramed and plotted at the bottom of the GUI.  When all voltages are on at their set values, the display turns green.
+
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Changes to the voltage settings are only allowed by an expert, or under his/her guidance.
+
−
 
+
−
== Interlocks==
+
−
The voltages and the chiller are interlocked using the temperature and dew point measurements described in [[#Checking the environment | Checking the environment]]. If the temperature exceeds the
+
−
preset value in the GUI, or the dew point comes within a predetermined window of the measured temperature, or the chiller goes off, the interlock will be set and it will disable the voltage supply crates
+
−
and turn off the chiller. Changes to the interlock settings  are only allowed by an expert, or under his/her guidance.
+
−
 
+
−
== Expert personnel ==
+
−
The individuals responsible for checking that the BCAL is ready to take data  and setting its operating parameters  are shown in following table.
+
−
Problems with normal operation of the BCAL should be referred to those individuals and any changes to their settings must be
+
−
approved by them. Additional experts may be trained by the system owner and their name and signature added to the document residing in the Hall D Counting House.
+
  
 
  {| border=1  
 
  {| border=1  
−
|+ Table:  Expert personnel for the BCAL system
+
|+ Table:  Expert personnel for the FDC system
 
|- bgcolor=#DFDFDF   
 
|- bgcolor=#DFDFDF   
 
! width=200px | Name    !!  width=100px | Extension !! Date of qualification  
 
! width=200px | Name    !!  width=100px | Extension !! Date of qualification  
 
|-
 
|-
−
| Elton Smith    ||  align=center | 269-7625   ||  align=center | May 20, 2014
+
| Lubomir Pentchev    ||  align=center | 269-5470   ||  align=center | June 3, 2014
 
  |}
 
  |}
−
 
−
-->
 

Latest revision as of 16:39, 3 July 2014

The Forward Drift Chambers

The Forward Drift Chamber (FDC) system consists of four identical packages (named FDC1 to FDC4), each having six chambers or cells (named CELL1 to CELL6). These are planar drift chambers with both anode wires and cathode strips being readout, in total 12,672 channels.

The cells within a package have independent gas volumes, but are separated with a flexible mylar membrane. Therefore, the pressure difference between neighboring cells should never exceed 30 Pa and should normally be less than 5 Pa. Note that the interlock should safeguard against excessive differential pressure.

Positive (up to 2200 V) and negative (up to 500 V) HV is applied on the sense and field wires respectively with currents not exceeding 3 microA per HV channel .

The detector (including cables) emits a total power of about 1500 Watt, of which about 900 Watt inside the magnet, due to the LV applied on the detector pre-amplifieres. A cooling system using Fluorinert is used to keep the temperature on the pre-amplifiers within the permissible limits. The LV system should never be turned ON if the cooling system doesn't work . The interlock should safeguard against this condition.

Routine operation

Fig. 1. FDC HV, LV GUI panel.
FDC & CDC gas panel including information about the colling systems. Fig. 2.

The most important task for the shift workers is to monitor the parameters (using GUIs) and report any changes from the normal operation for the following FDC related subsystems: High Voltage, Low Voltage (including thresholds), Gas system, and the Cooling system. A description of how to bring up the corresponding GUI screens and how to operate them can be found in Section Slow Controls. The HV and LV subsystems, as well as the Gas and Cooling systems have common GUIs. The GUIs are designed to show green color if all the parameters in a certain subsystem/subgroup are within the limits. If any of the parameters is out of limits the background for the corresponding subsystem/subgroup will turn red. Examples of the GUIs are shown in Figs. 1 and 2.

The shift workers are allowed, using the GUI, to turn ON and OFF all the HV and LV (including thresholds) systems, as well as parts of them or the individual channels. Instructions how to do this are given in Section Slow Controls, but the general rule is either to bring the pop-up menu with left click on the group title (like "ALL HV", or "FDC 1") or to click on the individual channel knob (the knob title shows the action to be taken after pressing it). For example, in case a HV channel trips, one should press the corresponding channel knob once (acknowledging the trip) and then again to turn it on. The corresponding voltage parameters, like rump up/down rates, trip currents, set voltage values etc. cannot be changed by the shift workers. The Gas and cooling system GUI is only to be monitored by the shift workers; the parameters there cannot be changed.

In addition to the operations using GUIs, the shift workers should visually check the gas panel in the Hall using the camera "halldaxis7" with remote control installed there, and make sure all the bubblers operate normally. For instructions how to operate the camera, refer to Section Slow Controls. Once per shift the workers are supposed to record the manometer values and inspect other components in the gas room; see Section Gas System.

Operations beyond what is specified above shall only be performed by the system expert or under his/her direction.

Interlocks

To prevent damage of the equipment in situations explained in the first paragraph (where the corresponding critical parameter limits were highlighted with red) interlock systems are implemented. Hardware interlock is used to turn OFF the power of the LV crate in case the cooling system fails. Software (PLC based) interlock system is implemented to turn off the gas supply if the pressure between any two neighboring cells exceeds 30 Pa. The HV and LV modules are set to immediately turn off the voltage if the current exceeds the corresponding limit. Setting the voltage channel back should be done only manually by the operator. We DO NOT use the automatic feature to keep the voltage (for a certain time) such that the current is at the limit.

Expert personnel

The individuals responsible for the operation of the FDC are shown in the following table. Problems with normal operation of the FDC should be referred to those individuals and any changes to their settings must be approved by them. Additional experts may be trained by the system owner and their name and date added to this table.

Table: Expert personnel for the FDC system
Name Extension Date of qualification
Lubomir Pentchev 269-5470 June 3, 2014
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