User's manual for DRAGON separator Hardware - Revision history

Lennarz: /* Electrostatic dipoles */

2023-11-09T19:31:38Z

Electrostatic dipoles

← Older revision		Revision as of 12:31, 9 November 2023
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	A spark in an ED or some other electromagnetic pulse may cause the DAC which sets electrode current limit to lose its calibration. A symptom of this is that when the HV is turned On, the voltage and current will momentarily ramp up but almost immediately go back down to near zero. A way to check for this problem is to use the "loopback" test of the CANBUS system: from the DRAGON EPICS menu select Diagnostics\|Canbus and then the ED in question. For the problem electrode (+ or -) change the I button from "no LB" to put it in loopback mode, whereby the DAC output is fed directly back into the ADC. Run the appropriate slider bar up and down and you should normally see the Readback and Setpoint values move up and down together. If they do so, you have a different problem and should call an HV Expert. If they do not have the same value, try to recalibrate the DAC: momentarily unplug the CANBUS daisy chain input to the controller box in question (ask an ISAC Operater for help with this). If this doesn't fix the problem, call an HV Expert. NOTE: unplugging the CANBUS will cause all CANBUS-controlled devices (magnets, ED) to forget their settings and they must be turned on again and set to proper values.		A spark in an ED or some other electromagnetic pulse may cause the DAC which sets electrode current limit to lose its calibration. A symptom of this is that when the HV is turned On, the voltage and current will momentarily ramp up but almost immediately go back down to near zero. A way to check for this problem is to use the "loopback" test of the CANBUS system: from the DRAGON EPICS menu select Diagnostics\|Canbus and then the ED in question. For the problem electrode (+ or -) change the I button from "no LB" to put it in loopback mode, whereby the DAC output is fed directly back into the ADC. Run the appropriate slider bar up and down and you should normally see the Readback and Setpoint values move up and down together. If they do so, you have a different problem and should call an HV Expert. If they do not have the same value, try to recalibrate the DAC: momentarily unplug the CANBUS daisy chain input to the controller box in question (ask an ISAC Operater for help with this). If this doesn't fix the problem, call an HV Expert. NOTE: unplugging the CANBUS will cause all CANBUS-controlled devices (magnets, ED) to forget their settings and they must be turned on again and set to proper values.

			===ED high voltage conditioning===
	The electrodes must be "conditioned" for stable operation at high voltage. As the voltage is increased, at some point the current will jump up to the current limit of the supply, vacuum will get worse by an order of magnitude, and the x-ray counts will jump from from tens or hundreds per second to many tens of thousands per second. If the voltage is set just above the onset of these effects, the system should return to good vacuum, low x-ray counts and 1 µA per kV within a minute or so. Then the voltage can be raised slightly and the cycle repeated. For detailed instructions on HV conditioning, consult the [[ED conditioning\|EPICS routine for conditioning ED1, ED2 at high voltage]].		The electrodes must be "conditioned" for stable operation at high voltage. As the voltage is increased, at some point the current will jump up to the current limit of the supply, vacuum will get worse by an order of magnitude, and the x-ray counts will jump from from tens or hundreds per second to many tens of thousands per second. If the voltage is set just above the onset of these effects, the system should return to good vacuum, low x-ray counts and 1 µA per kV within a minute or so. Then the voltage can be raised slightly and the cycle repeated. For detailed instructions on HV conditioning, consult the [[ED conditioning\|EPICS routine for conditioning ED1, ED2 at high voltage]].

Lennarz: /* Electrostatic dipoles */

2023-11-09T19:29:10Z

Electrostatic dipoles

← Older revision		Revision as of 12:29, 9 November 2023
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	Dipoles ED1 and ED2 consist of polished cylindrical titanium electrodes having a gap of 100 mm and radii of curvature 2 m for ED1, 2.5 m for ED2. Design bending power is 8 MV (energy/charge 4 MeV/q) which requires electrode voltages of ±200 kV on ED1, ±160 kV on ED2. They are housed in large cylindrical tanks. The HV units are stacks powered by Glassman r.f. supplies; the stacks are immersed in SF6 gas at 2 atm, enclosed in re-entrant ceramic insulating cylinders.		Dipoles ED1 and ED2 consist of polished cylindrical titanium electrodes having a gap of 100 mm and radii of curvature 2 m for ED1, 2.5 m for ED2. Design bending power is 8 MV (energy/charge 4 MeV/q) which requires electrode voltages of ±200 kV on ED1, ±160 kV on ED2. They are housed in large cylindrical tanks. The HV units are stacks powered by Glassman r.f. supplies; the stacks are immersed in SF6 gas at 2 atm, enclosed in re-entrant ceramic insulating cylinders.

	The tank is encased in 6 mm of lead, to absorb x-rays given off during voltage conditioning. X-ray production is monitored by thick plastic scintillators connected to photo-multiplier tubes, mounted above a viewing port on the lid of each vacuum tank. The PMT high-voltage supply is ~~a LeCroy~~ unit, ~~manually~~ controlled~~, in the 19'' rack below the platform~~. Customary HV setting is -2000 V. A discriminator in the ~~same~~ rack provides logic signals which are made available to the EPICS control system.''		The tank is encased in 6 mm of lead, to absorb x-rays given off during voltage conditioning. X-ray production is monitored by thick plastic scintillators connected to photo-multiplier tubes, mounted above a viewing port on the lid of each vacuum tank. The new PMT high-voltage supply is the iseg HV unit (tail rack), remote controlled (dragonhv02.triumf.ca/). Customary HV setting is -2000 V. A discriminator in the rack under the platform provides logic signals which are made available to the EPICS control system.''

	The Glassman supplies are close to their respective electrodes, in a 19'' rack for the anodes and slung from the vacuum tank for the cathodes. They are controlled via a Canbus link. The AC to the Glassman supplies is interlocked: cages around the feed-throughs to the stacks must both be closed; there must be less than 0.5 atm in the tank as measured by a mechanical gauge; there must be less than 10\-5 Torr in the tank as measured by an ion gauge; at least one of the tank pumps (turbo, cryo or ion) must be on. The interlock boxes are located in the racks that hold the anode power supplies.''		The Glassman supplies are close to their respective electrodes, in a 19'' rack for the anodes and slung from the vacuum tank for the cathodes. They are controlled via a Canbus link. The AC to the Glassman supplies is interlocked: cages around the feed-throughs to the stacks must both be closed; there must be less than 0.5 atm in the tank as measured by a mechanical gauge; there must be less than 10\-5 Torr in the tank as measured by an ion gauge; at least one of the tank pumps (turbo, cryo or ion) must be on. The interlock boxes are located in the racks that hold the anode power supplies.''

Lennarz: /* Beta monitor */

2023-11-08T17:57:23Z

Beta monitor

← Older revision		Revision as of 10:57, 8 November 2023
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	The HV (-1900V each) for the plastic scintillator photo-multiplier tubes is now supplied from channels 11 and 12 of the remote controlled new iseg HV power supply unit (EHS F630n). The physical location of the HV module is in the right tail rack. To bias the monitors, visit dragonhv02.triumf.ca. The discriminators, coincidence unit, and level adapter modules are in the same NIM crate in the rack under the platform.		The HV (-1900V each) for the plastic scintillator photo-multiplier tubes is now supplied from channels 11 and 12 of the remote controlled new iseg HV power supply unit (EHS F630n). The physical location of the HV module is in the right tail rack. To bias the monitors, visit dragonhv02.triumf.ca. The discriminators, coincidence unit, and level adapter modules are in the same NIM crate in the rack under the platform.

			The scaler variable for beta coincidences is DRA:SCLR1:VAR7 and the scaler variable for beta singles is DRA:SCLR1:VAR8. They can be found on the DRAGON virtual epics scaler page.

	Drawings and notes on expected efficiency for detection of betas from decay of Na-21 beam from DAH logbook:		Drawings and notes on expected efficiency for detection of betas from decay of Na-21 beam from DAH logbook:

Lennarz: /* Beta monitor */

2023-11-08T17:54:30Z

Beta monitor

← Older revision		Revision as of 10:54, 8 November 2023
Line 167:		Line 167:
	[[File:Beta1.png\|center\|frameless]]		[[File:Beta1.png\|center\|frameless]]

	The HV for the plastic scintillator photo-multiplier tubes is from channels 2 and 3 of the ~~same LeCroy~~ HV unit ~~which supplies~~ the ~~ED x-ray~~ monitors. The discriminators, coincidence unit, and level adapter modules are in the same NIM ~~bin as~~ the ~~NMR controllers (~~rack under the platform).		The HV (-1900V each) for the plastic scintillator photo-multiplier tubes is now supplied from channels 11 and 12 of the remote controlled new iseg HV power supply unit (EHS F630n). The physical location of the HV module is in the right tail rack. To bias the monitors, visit dragonhv02.triumf.ca. The discriminators, coincidence unit, and level adapter modules are in the same NIM crate in the rack under the platform.

	Drawings and notes on expected efficiency for detection of betas from decay of Na-21 beam from DAH logbook:		Drawings and notes on expected efficiency for detection of betas from decay of Na-21 beam from DAH logbook:

Akatrusiak: added RF timing system description and operation

2023-07-19T22:29:24Z

added RF timing system description and operation

← Older revision		Revision as of 15:29, 19 July 2023
Line 178:		Line 178:

	The location of the gas cell aperture may be determined by closing isolation valve HEBT2:IV8 and turning on ion gauge IGU3 (and opening valve IV11!). The outline of the 6mm cell entrance aperture appears backlit by light scattered off IV8.		The location of the gas cell aperture may be determined by closing isolation valve HEBT2:IV8 and turning on ion gauge IGU3 (and opening valve IV11!). The outline of the 6mm cell entrance aperture appears backlit by light scattered off IV8.


			=== RF timing calibration system ===
			The system to find BGO-vs-RF time for a resonance at z=0. A calculation of the time of arrival of a beam bunch at z=0 in the gas cell, relative to the supplied RF signal, requires 3 inputs: phase of the RF in the final stage of acceleration, relative to the supplied signal; velocity of the beam after the accelerator; net velocity change by the buncher. The requirement can be satisfied more directly by measurement by insertion of a fast scintillator into the beam at a point close to the gas cell. Such a scintillator has been built and mounted in the access port just upstream of Q1. '''The scintillator is not rad-hard and exposure to beam should be limited and rates kept <100Hz.

			The detector is a 1cm x 1cm x 0.3cm plastic scintillator (BC-404) sitting upright on a light guide that is attached to a Hamamatsu 6427 PMT. An electron of 1MeV produces a signal of about 1V at PMT bias -1200V and about 6V at -1500V (max bais). Heavy ions have a much lower light output per MeV of kinetic energy loss, due to saturation effects. A rough estimate is that the light output is the same as that of an electron having (1.25 R)% of the heavy ion's kinetic energy, where R is the ion range in C in mg/cm^2

			The PMT signals have ns rise times and are input directly into a 621 discriminator with threshold set at -30mV. Coincidence with a second 621 unit set at a higher threshold eliminates noise pulses which just reach the 30mV level.
			NOTE: owing to a dearth of NIM coincidence units, the coincidence is implemented as A and B = not(notA or notB)

			<insert picture>

			==== Operation of the timing system ====
			# While the beam is being tuned the PMT ladder should be in the "large hole" position (132mm, center of slot on screw) and the PMT HV off (LeCroy HV unit, channel 5). When beam tuning is complete, attenuate the beam intensity to 100Hz or less, as seen on the end detectors
			# Set up MIDAS with "PMT only" head trigger mode. In MIDAS, select ODB/Equipment/HeadVME/Settings/IO32 and set ChannelEnable[3] to 'y'; set channels 0-2 to 'n'
			# Insert cup FC4 with script "fc4in.sh", close valve IV11 and turn off gauge IGD4 (and its light).
			# Connect the timing scintillator signal to a scope and run the scintillator HV to -1200V
			# Remove FC4 with script "fc4out.sh", and raise the ladder to position indicated on the sheet taped to the ladder (slowly for the last 5mm in case beam intensity is to high) while anaccomplice watches on the scope for signals. Signals should appear within a narrow band of amplitudes. Adjust the HV so that signals are 100s of mV and the "High" discriminator is set at -100mV. Verify that the RF signal is in phase with the beam pulses on the few-ns scale.
			# Do a MIDAS run, verifying that the RF time spectrum is a plausible width and the centroid can be dtemined with sub-ns precision. Record scintillator HV and signal size in the run comments.
			# Insert FC4, run down the HV to minimum, lower the ladder to "large hole" (132mm) and turn on IGD4 and open valve IV11. Restore the normal head trigger in MIDAS (channels 0-2 to 'y' and channel 3 to 'n')
			NOTE: removal of the ladder system after an experiment is best done with two people, one to lift and one to undo the internal connections of the HV and signal cables

	== Vacuum ==		== Vacuum ==

Lennarz: /* Beta monitor */

2022-06-10T23:41:58Z

Beta monitor

← Older revision		Revision as of 16:41, 10 June 2022
Line 171:		Line 171:
	Drawings and notes on expected efficiency for detection of betas from decay of Na-21 beam from DAH logbook:		Drawings and notes on expected efficiency for detection of betas from decay of Na-21 beam from DAH logbook:
	[[File:Beta efficiency.png\|center\|frameless]]		[[File:Beta efficiency.png\|center\|frameless]]

	~~[[File:Betax.png\|center\|xxx]]~~

	=== CCD camera ===		=== CCD camera ===

Lennarz: /* Beta monitor */

2022-06-10T23:41:37Z

Beta monitor

← Older revision		Revision as of 16:41, 10 June 2022
Line 171:		Line 171:
	Drawings and notes on expected efficiency for detection of betas from decay of Na-21 beam from DAH logbook:		Drawings and notes on expected efficiency for detection of betas from decay of Na-21 beam from DAH logbook:
	[[File:Beta efficiency.png\|center\|frameless]]		[[File:Beta efficiency.png\|center\|frameless]]

			[[File:Betax.png\|center\|xxx]]

	=== CCD camera ===		=== CCD camera ===

Sriteja: added images and changed a link to the ED conditioning

2022-03-24T23:51:07Z

added images and changed a link to the ED conditioning

← Older revision		Revision as of 16:51, 24 March 2022
Line 125:		Line 125:
	A spark in an ED or some other electromagnetic pulse may cause the DAC which sets electrode current limit to lose its calibration. A symptom of this is that when the HV is turned On, the voltage and current will momentarily ramp up but almost immediately go back down to near zero. A way to check for this problem is to use the "loopback" test of the CANBUS system: from the DRAGON EPICS menu select Diagnostics\|Canbus and then the ED in question. For the problem electrode (+ or -) change the I button from "no LB" to put it in loopback mode, whereby the DAC output is fed directly back into the ADC. Run the appropriate slider bar up and down and you should normally see the Readback and Setpoint values move up and down together. If they do so, you have a different problem and should call an HV Expert. If they do not have the same value, try to recalibrate the DAC: momentarily unplug the CANBUS daisy chain input to the controller box in question (ask an ISAC Operater for help with this). If this doesn't fix the problem, call an HV Expert. NOTE: unplugging the CANBUS will cause all CANBUS-controlled devices (magnets, ED) to forget their settings and they must be turned on again and set to proper values.		A spark in an ED or some other electromagnetic pulse may cause the DAC which sets electrode current limit to lose its calibration. A symptom of this is that when the HV is turned On, the voltage and current will momentarily ramp up but almost immediately go back down to near zero. A way to check for this problem is to use the "loopback" test of the CANBUS system: from the DRAGON EPICS menu select Diagnostics\|Canbus and then the ED in question. For the problem electrode (+ or -) change the I button from "no LB" to put it in loopback mode, whereby the DAC output is fed directly back into the ADC. Run the appropriate slider bar up and down and you should normally see the Readback and Setpoint values move up and down together. If they do so, you have a different problem and should call an HV Expert. If they do not have the same value, try to recalibrate the DAC: momentarily unplug the CANBUS daisy chain input to the controller box in question (ask an ISAC Operater for help with this). If this doesn't fix the problem, call an HV Expert. NOTE: unplugging the CANBUS will cause all CANBUS-controlled devices (magnets, ED) to forget their settings and they must be turned on again and set to proper values.

	The electrodes must be "conditioned" for stable operation at high voltage. As the voltage is increased, at some point the current will jump up to the current limit of the supply, vacuum will get worse by an order of magnitude, and the x-ray counts will jump from from tens or hundreds per second to many tens of thousands per second. If the voltage is set just above the onset of these effects, the system should return to good vacuum, low x-ray counts and 1 µA per kV within a minute or so. Then the voltage can be raised slightly and the cycle repeated. For detailed instructions on HV conditioning, consult the [EPICS routine for conditioning ED1, ED2 at high voltage]~~(HVconditioning.html)~~.		The electrodes must be "conditioned" for stable operation at high voltage. As the voltage is increased, at some point the current will jump up to the current limit of the supply, vacuum will get worse by an order of magnitude, and the x-ray counts will jump from from tens or hundreds per second to many tens of thousands per second. If the voltage is set just above the onset of these effects, the system should return to good vacuum, low x-ray counts and 1 µA per kV within a minute or so. Then the voltage can be raised slightly and the cycle repeated. For detailed instructions on HV conditioning, consult the [[ED conditioning\|EPICS routine for conditioning ED1, ED2 at high voltage]].

	Note: If signs of conditioning persist for more than approx. 1 minute after a small increase in voltage (say 10 V), this may indicate a problem such as carbon tracking along the ceramic insulator or within the HV stack; reduce the voltage and consult an HV expert.		Note: If signs of conditioning persist for more than approx. 1 minute after a small increase in voltage (say 10 V), this may indicate a problem such as carbon tracking along the ceramic insulator or within the HV stack; reduce the voltage and consult an HV expert.
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	=== Beta monitor ===		=== Beta monitor ===
	The Beta monitor is a pair of plastic scintillators which detect beta particles emitted by radioactive beam atoms which stop in the Mass slit. Located in air in a well in the Mass focus diagnostics box, the Beta monitor subtends about 1/1500 of 4 pi solid angle at XSLITM. The rate for coincidence detection of a particle in the two scintillators is presented to the EPICS virtual scaler and the MIDAS DAQ. The coincidence response depends upon the energy distribution of the decay betas: a detected beta must have eneough energy to pass through the entrance window, through the first scintillator (6mm) and far enough into the second scintillator to be above discriminator threshold. As well as the coincidence rate, the front-counter singles rate is sent to the MIDAS scaler. Connection is by a coax cable as indicated by the blue line:		The Beta monitor is a pair of plastic scintillators which detect beta particles emitted by radioactive beam atoms which stop in the Mass slit. Located in air in a well in the Mass focus diagnostics box, the Beta monitor subtends about 1/1500 of 4 pi solid angle at XSLITM. The rate for coincidence detection of a particle in the two scintillators is presented to the EPICS virtual scaler and the MIDAS DAQ. The coincidence response depends upon the energy distribution of the decay betas: a detected beta must have eneough energy to pass through the entrance window, through the first scintillator (6mm) and far enough into the second scintillator to be above discriminator threshold. As well as the coincidence rate, the front-counter singles rate is sent to the MIDAS scaler. Connection is by a coax cable as indicated by the blue line:
			[[File:Beta1.png\|center\|frameless]]
	![~~](images/beta1~~.png)

	The HV for the plastic scintillator photo-multiplier tubes is from channels 2 and 3 of the same LeCroy HV unit which supplies the ED x-ray monitors. The discriminators, coincidence unit, and level adapter modules are in the same NIM bin as the NMR controllers (rack under the platform).		The HV for the plastic scintillator photo-multiplier tubes is from channels 2 and 3 of the same LeCroy HV unit which supplies the ED x-ray monitors. The discriminators, coincidence unit, and level adapter modules are in the same NIM bin as the NMR controllers (rack under the platform).

	Drawings and notes on expected efficiency for detection of betas from decay of Na-21 beam from DAH logbook:		Drawings and notes on expected efficiency for detection of betas from decay of Na-21 beam from DAH logbook:
			[[File:Beta efficiency.png\|center\|frameless]]
	![~~](images/beta_effcy~~.png)

	=== CCD camera ===		=== CCD camera ===

Sriteja: Created page with "== Magnets == The DRAGON magnets include 2 dipoles (MD1, MD2), 10 quadrupoles (Q1-Q10), 4 sextupoles (SX1-SX4) and 5 double steerers (SM0-SM4). Regulated DC power supplies for..."

2022-03-24T23:44:23Z

Created page with "== Magnets == The DRAGON magnets include 2 dipoles (MD1, MD2), 10 quadrupoles (Q1-Q10), 4 sextupoles (SX1-SX4) and 5 double steerers (SM0-SM4). Regulated DC power supplies for..."

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