Photos status April 20 2007.
Polarized Target Wiki.
Polarized Target Elog.
Target polarization data repository.
Target cryogenics data repository.
Programs for analysing NMR-signals and cryogenics data.
Small utilities: dcsread,
Minutes from weekly meetings 2015.
Minutes from weekly meetings 2014.
Minutes from weekly meetings 2013.
Minutes from weekly meetings 2012.
Minutes from weekly meetings 2011.
Minutes from weekly meetings 2010.
Electronic log book 2010.
Target shifts with small changes and additions to the official shift list. Also target week coordinations are included.
Simple text file from the shift list.
Minutes from weekly meetings 2009.
Minutes from weekly meetings 2008.
NMR files on web page by Takuma.
Electronic log book 2007.
First target shifts.
End of run shifts.
Minutes from weekly meetings 2007.
40 mm NH3 target 2007 v0.1 in
and in black and white.
40 mm NH3 target 2007 v0.1 in
and in black and white.
Preliminary polarization P1B - P3B.
Electronic log book 2006.
Shift list 2006.
Minutes from weekly meetings 2006.
Polarized Nucleon Targets for Europe in the 6th European Framework Program (Rech).
Takeshis report on target
packing factor simulations to understand the geometrical cuts used in the
Pauls report on spin temperature
analysis of the highest polarization values 2001 - 2004.
NMR tools HOWTO.
NMR field maps.
Minutes from weekly meetings 2005.
Polarized Nucleon Targets for Europe in the 6th European Framework Program (Miltenberg).
XIth International Workshop on Polarized Sources and Targets November 14-17, 2005, Tokyo, JAPAN.
Yuris talk on cavity testing April 14.
Mauricios talk on Mainz Microtron (MAMI) microwave system August 16.
Roberts report on polarization
data quality in run log book 2002 - 2004.
Jaakkos talk on cavity feeding October 6.
Jaakkos poster in PST05 November 14.
Norihiros photos on dilution cryostat and new 180 mrad superconducting magnet December 5.
Preliminary polarization P1A - P2C.
Field rotation times 2004.
Histogram of field rotation times 2004.
Electronic log book 2004.
Shift list 2004.
Minutes from weekly meetings 2004.
Aoibhinns report on new mixing chamber.
Drosoulas calculations on NMR coil field and polarization distribution.
Isabels analysis of 2004 TE-calibration signals.
Isabels talk on 2004 TE-calibration July 29.
Jaakkos technical board talk January.
Jaakkos offline talk.
Jaakkos talk on PT removal September.
Kaoris collaboration meeting talk August 27. All Kaoris talks, plots and reports 2001 - 2004.
Preliminary polarization P2A - P2E.
Field rotation times 2003.
Histogram of field rotation times 2003.
Preliminary polarization 2003.
Electronic log book 2003.
Shift list 2003.
Shift histogram 2003.
Minutes from weekly meetings 2003.
Kaoris collaboration talk in February.
Jaakkos collaboration talk in April.
Jaakkos collaboration talk in October Lisbon.
Jaakkos talk October in Bad Honnef.
Jaakkos collaboration talk in December.
Isabels polarization analysis 2003.
Kristins report on target PLC.
Kristins diagrams on target PLC.
Preliminary polarization P1B - P2C.
Field rotation times 2002.
Histogram of field rotation times 2002.
Minutes from weekly meetings 2002.
Jaakkos collaboration talk in November.
The target operated well from 18th of June to 18th of September.
There were two transverse polarization mode periods with
microwave polarization reversal in the middle.
First of them was from 3rd of August to 12th of August. Second one was
from 11th of September to 18th of September.
In the beginning the upstream target cell had negative polarization while
the downstream target cell had positive polarization. After the microwave
polarization reversal on 6 - 8th of August the upstream target cell had
positive polarization while the downstream cell had negative polarization.
During the run the polarization was lost 4 times due to loss of magnetic field.
In the run 2002 about 405 eight hour target shifts were done. 342 of these
were during the beam time, 42 before and 21 after. Thanks to the about 50
persons from the collaboration who took part in the target shifts.
Preliminary polarization 2002..
Online average polarization 2002..
Preliminary polarization P2A - P2B.
Minutes from weekly meetings 2001.
Jaakkos collaboration talk in January.
Jaakkos collaboration talk in March.
Jaakkos TB talk in May.
Jaakkos collaboration talk in June.
For the year 2001 the old magnet from the SMC experiment was installed on the
A new microwave cavity fitting inside the magnet 265 mm diameter bore
was manufactured (May - Jul 2001).
The cavity has 0.5 mm down stream end window made of copper. The two target
halves are separated by a microwave stopper made from 0.1 mm copper foil.
The mixing chamber is the same as in the SMC experiment.
With the two target cells (each 60 cm long and diameter 3 cm)
separated by 10 cm
distance in the center of the solenoid this leads to an acceptance of 69 mrad.
Big effort between CERN and Saclay was needed to get the magnet work in
very short time (May - Aug 2001).
The target material 6LiD from Bochum was successfully loaded
inside the mixing chamber (Aug 2001).
first polarization runs (Sep 2001)
have resulted to negative and positive polarizations from 45 to 50 %
( zipped ppt-file ).
To confirm these values more NMR data is being collected.
Jaakkos collaboration talk in April.
Jaakkos collaboration talk in July.
Jaakkos TB talk in October.
Jaakkos TIS talk in October.
COMPASS uses solid polarized proton and deuteron targets in the muon
program. The target material is either
The nuclear spins are polarized with dynamic nuclear polarization (DNP),
based on microwave saturation of impurity electron spins near their
paramagnetic resonance in a 2.5 T longitudinal field.
The two target cells have the length of 60 cm and a diameter of 3 cm,
and they are polarized in opposite directions.
Magnetic poles of the SMC and COMPASS solenoids
The magnetic poles of the solenoid were measured with a compass.
The photos of the measurements 2003 - 2004
are here and
for 2006 here.
The 2007 photos.
A test solenoid was used to determine how the magnetic poles correspond
to the magnetic field direction.
The photos are here.
The measured magnetic poles for positive solenoid
current. The field direction is determined inside solenoid.
|Date || Upstream || Downstream || Field direction |
| 2002 July 22 || South || North
|| ups <- dws |
| 2003 July 3 || South || North
|| ups <- dws |
| 2004 June 11 || South || North
|| ups <- dws |
| 2006 July 26 || North || South
|| ups -> dws |
The Canadian Geological Survey definition of the North Magnetic Pole is here
Magnetic poles of the target spin magnetization
The spin magnetization poles can be determined from the known solenoid current
sign and from the sign of the polarization as follows:
Spin magnetization poles for positive and negative
currents. First is the upstream pole and the second is the downstream pole
of the target cell. Also the direction of spin is shown for nuclei with
positive gyromagnetic ratio, e.g. deuterium.
| || positive polarization || negative polarization
|| positive polarization || negative polarization |
| positive current 2002 - 2004 || South-North
|| North-South || ups <- dws || ups -> dws |
| negative current 2002 - 2004 || North-South
|| ups -> dws || ups <- dws |
| positive current 2006 || North-South
|| South-North || ups -> dws || ups <- dws |
| negative current 2006 || South-North
|| ups <- dws || ups -> dws |
Due to the requirement of larger acceptance of 180 mrad a
new superconducting magnet has been ordered from
The details of the magnet design were fixed in March 97. The magnet
is expected to provide a longitudinal field of max. 2.7 T with
100 ppm inhomogeneity
over the target volume and a vertical 0.6 T field with 9% inhomogeneity.
The magnet is being tested at Oxford
Instruments (Jan - Sep 2001). Unfortunately in testing
phase unexplained quenches were observed at field less than required by
magnet specifications. Oxford Instruments is studying the reason for these
quenches to understand what actions are needed to make operation stable
(Apr - Sep 2001).
Installation at CERN including
field mapping inside magnet and adjustment of trim coil currents with and
without spectrometer magnet SM1 is expected to take 8 - 10 weeks.
A calculated field map close to magnet is already available.
See Nagoya Polarized Target Group.
Here is a side view of the magnet..
The solenoid is powered with the
while for the dipole coil we
use the old Drusch power supply from SMC. The magnet has a
Quench Back Heater system to cause a forced
quench if quench in some part of the solenoid is detected.
The burst disk gives the
ultimate safety in sudden evaporation of LHe.
The suspension system
the solenoid in place even when SM1 is powered and a large torque is
acting on the coil. The magnet is connected to the dilution cryostat
from the upstream flange.
System integration between Oxford Instruments magnet and CERN facilities is
being discussed. Here is information about the
old SMC cryogenic system.
COMPASS will use the old Drusch power supply for the dipole magnet and
the safety interlock unit to prevent energizing of dipole if solenoid
has more that 1/3 of its maximum field.
Safety issues concerning the magnet installation have been discussed with
. Mainly this concerns the pressure vessel safety code D2,
magnetic field and operation safety.
For the Oxford magnet the main modification to the SMC cryostat was
Otherwise the cryostat is
the same. The beam goes in from here.
Here is a schematic diagram of
dilution cryostat with the magnet.
The conical cavity inside the magnet
has 100 um thick Cu foil at its end. Such a thin foil can not stand
any practical pressure difference. Thus the cavity vacuum will be shared
with Oxford magnet vacuum.
This is different from the SMC experiment where the cavity was isolating
the vacuum outside of the mixing chamber from magnet vacuum and worked as
an extra protection in case that the glass fiber mixing chamber for some
reason starts to leak. This could happen for example when the target
material is being loaded. In this procedure there
are mechanical forces to the mixing chamber.
Since the muon beam is now focused to 30 mm diameter a smaller diameter
chamber can be used. The volume of target material and helium surrounding it
was the same for the SMC target. Thus the mixing chamber could be made
to 45 mm in diameter. Thus a new glass fiber mixing chamber is being prepared.
It has to be leak and pressure tested before it can be accepted. In normal
operation the mixing chamber has to stand + 1 atm pressure.
Leak testing of the new mixing chamber showed no
leaks at room temperature (Sep 2000). Unfortunately in cooling down with
LN2, two of the three glass fiber tubes started to leak. They were inspected
after opening the test vacuum vessel and cracks were seen close to the
Leak and flow tests at room temperature showed (Dec 1999 - Jan 2000)
that the cryostat is ok. One epoxy feed through from still was leaking to
vacuum, but was easy to fix.
A cryogenic leak test was be done in
March 2001. The leak rate stayed at 10^-9 mbar l/s and isolation vacuum
pressure below 10^-7 mbar during the one week period that the cryostat
was cold. The minimum temperature obtained was only about 0.25 K due to
missing 4 K radiation shield, i.e. only 80 K radiation shield was used.
More careful technical run will be needed to verify proper operation
of heat exchangers and to check thermometer calibration.
Due to new focusing of the muon beam from 50 mm diameter to 30 mm diameter, the
polarized target had to be moved 20 m down stream compared to its position
in the SMC experiment.
A new pump hut
had to be constructed and new pumping lines welded.
The cooling water circuit for the pumps
and pressurized air for electro-pneumatic valves are both ready
The roots blowers were tested (Feb - Mar 2001). The test included
purging by pumping dry nitrogen for several days, helium leak tests and
pumping of helium gas for a week to see how much air impurity is accumulated
into LN2 trap.
was responsible of the testing.
4He pumps were tested after the roots blowers.
The 4He pumping and exhaust tubes were installed with
bypass and overpressure valves and manometers.
The control panel has new purifier
cartridges and the LN2 trap new charcoal in it. Both are kept under vacuum
when the dilution cryostat is not run. The trap and purifiers were
also leak tested before they were put in to use.
The 3He tanks were connected to
A new hermetic pump from Alcatel 2033H was bought for reliable recovery of
3He (which has value of about 250 kCHF) in all conditions.
Mixture inventory was made 15th of March 2001 by AT/ECR/Cryolab.
1387 l NTP of
3He gas was found. In addition we have 7198 l NTP of
Diagram of the pumping system status 2004 (A1 size PDF file).
PLC main page (only from CERN). Slow and needs right version of Java Runtime Environment.
PLC still heater interlock.
PLC LN2 trap.
PLC microwave interlock.
PLC LHe and LB2 levels.
PLC flows and temperatures.
Has been tested to give 75 l/h of helium liquid to the 2000 l buffer dewar.
This has be boosted to 100 l/h or more, with LN2 cooled on line purifier
The cold box was upgraded with parts coming from LEP experiment
(Jan 2001). Oxygene level of returning helium gas was measured to be
on the level of 10 ppm when both the magnet and dilution cryostat
were operated simultaneously (Aug 2001).
The cryostat needs 15 - 40 l/h depending on the 3He flow and
the magnet about 10 - 20 l/h at full field.
The helium recovery goes back to the cold box. In case of a quench
the evaporating helium gas is vented to the experimental hall
through the over pressure valves of SMC magnet.
of COMPASS cold box for information about liquid helium available for
Polarized target needs liquid nitrogen for precooling of the magnet. The
precooling of SMC magnet takes about 5 days. When the target material is being
loaded, it is stored into a liquid nitrogen bowl at target loading
platform. During the operation of the dilution cryostat the LN2 is used
in the cold trap to prevent impurities coming from roots blowers from
blocking the 3He return line inside cryostat.
NMR Polarization Measurement
The old Liverpool Q-meters are used. The NMR-coils embedded into
target material in 2001 were saddle coils 10 mm diameter and 70 mm long for
deuterium target. Each target cell had 5 coils. The coils were made from
1.6 mm diameter CuNi tube, which was covered with a PTFE tube. To improve
the target material packing factor the coils were mounted on the outside of
the target cells for the runs 2002 - 2004. Four coils were used on each target
cell. In addition there was one or two coils embedded into the target material
close to the microwave stopper. The coils were made of 1.0 mm diameter
resistive CuNi tube. Saddle shape was used with length of 60 mm and diameter
of 32 mm. For more info see
To analyse the NMR data you can check the
NMR tools HOWTO.
Photos of the Liverpool Q-meters.
Main concern was the new very thin microwave stopper. In the SMC cryostat the
stopper was made of several 1 mm copper plates. It had about 3 kg of copper.
Such amount of material could not be accepted for the COMPASS. Thus it was
important to study how well a thin 100 um foil could separate the two
target halves. The results were much worse than expected from simple skin
depth (about 1 um at 70 GHz for Cu). The reason in tests turned out be poor
contact of the foil to the surrounding cavity. Finally the leak was around
0.1 uW level, which was also the measurement limit. It is not possible to
measure better isolations than this with the microwave table. We would
need more powerful microwave source or more sensitive power meter.
For more info see Nagoya Polarized Target Group.
Electricity and pressurized air was available on the
platform from Jan 2001. Connections and tubes for normal and demineralised
cooling water have been installed. Demineralised cooling water was
available from Apr 2001.
The LHe transfer line to buffer dewar and
support arm for cables
are both installed and ready.
Platform power September 2005.
Platform power January 2006.
The control room has all the racks inside.
The instrumentation and cabling for flow controllers, flow meters, pressure
transducers, pressure gauges, resistance and diode thermometers is ready
and operational. Most important parameters are captured to the "multireg"
chart recorder, which also generates alarms if certain parameters go outside
their normal operation range (roots backpressure, LN2 trap level,
isolation vacuum, evaporator level).
The control software for the target cryostat and NMR is done with
LabVIEW in Windows NT.
It controls and monitors cryostat and NMR system through GPIB bus and a
VME crate. For the NMR a dedicated PC is installed. During the cool down
of the cryostat the
PC was used to record the different parameters
of the cryostat. The
present status of the target
can be seen on the web. For the SMC magnet the old Sun system is used for
See Bochum Polarized Target Group. They are working on 6LiD.
See COMPASS web camera if
you want to know what is happening right now in the experimental area.
Inventory February 2003.
Inventory April 2005.
Leak test September 2005.
Inventory February 2007.
Leak test February 2007.
Inventory March 2009.
Leak test March 2009.
Sharipov's gas flow in
Adixen(former Alcatel Vacuum Technology)
Agilent Technologies(former HP).
Emerson & Cuming
ET System electronic
Laboratory of Lightweight Structures
Norit activated carbon
Oxford Instruments Cryospares
Ziehl industrie-elektronik GmbH+Co
(tell me the missing names)
J-M Le Goff
This page was updated February 11 2016 by