==> Next meeting: to be defined after PROSPERO run
Present:
B. Allongue CERN
G. Bianchetti CERN
J. Crotty CERN & RIVERSIDE
G. Dumont CERN
R. Frei IPNL/Lausanne
A. Fucci CERN
Z. Hajduk CERN & CRACOW
B. Hallgren CERN
R. Richter CERN & MPI
U. Schaefer MAINZ
W. v. Sprolant CERN
G. Stefanini CERN
W. v. Sprolant: Preparation of PS-test at PROSPERO
(hardware)
Ten different types of DC-DC converters, two units of each, are prepared
for this irradiation test. One unit of each will be exposed to a n-dose
which corresponds to the one at the outer circumference of the ATLAS cavern
(2*10^11 n/cm^2, E(n)>100 keV) in 10 years. The other unit will be tested
up to the maximum dose we can obtain (about 10^13 at 3 m distance), possibly
leading to destruction.
A readout system has been developed to operate and constantly monitor
all devices during the irradiation. Devices will be loaded with 75% of
the specified maximum. The following parameters will be monitored: voltage,
current (in and out), voltage ripple. To reduce cabling, a muliplexing
system with mechanical relays is foreseen. As the relays are matched to
50 Ohm, voltage ripple can be observed in the control room without significant
interference.- All electronics which go into the irrad. zone are housed
in a rack, in such a way that cabling at the facility can be kept to a
minimum.
A test of the complete system at CERN is scheduled for sept. 15th.
Comment: It would be nice to be able to monitor the internal frequency of the DC-DC converter, because it reflects conversion efficiency.- This was agreed, however, it is not clear whether it can be implemented in time.
B. Allongue: Preparation of PS-test at PROSPERO (software)
Bruno described the readout architecture and DAQ. Apart from the quantities
mentioned above, the noise on the output voltage can be monitored with
a scope and the pictures stored on disc at regular intervals. (At a later
stage a spectrum analyser could be added.) Data will be recorded before,
during and after irradiation. The user interface is based on LabView.
B. Hallgren: Dosimetry results from irrad. in TCC2
The two runs in the TCC2 area have now been analysed for n- and gamma
doses. Compared to the previous estimates (c.f. minutes of 5th meeting)
doses are 4
times higher, i.e. the devices under test have seen 10^11 n/cm^2 in
the first and 10^12 n/cm^2 in the second run. (Total gamma doses are below
10 krad.)
This means that most components in the DCS-LMBs (Local Monitor Boards) have survived 5 times the LHC dose. Exceptions were the Siemens Optocoupler IL206A, whose CTR (current transfer ratio) was reduced to 30% of the initial value, and the ATMEL Processor, where some devices acquired permanent changes in some memory locations.
These devices will be submitted to the PROPERO test, where they can be operated and read out during irradiation.
Bjoern mentioned that the circuit design for the application of the Siemens Optocoupler could be modified in such a way as to allow operation with 30% CTR.
G. Stefanini: LV-power supplies in CMS
Giorgio announced that he was going to set up a task force on LV-PSs
and cable distribution in CMS. He is seeking a maximum of coordination
and co-operation with EES (electronics pool).
Z. Hajduk: Contacts with CAEN on HV and LV power supplies
Zbyszek has visited CAEN and had discussions with the staff. CAEN is
working on a new "universal" control crate for HV and LV. It can supply
up to 2250 W and will exist in 4U and 8U size. Various protocols will be
supported and there is also a variety of power supplies available. Work
is also going on on units, however the companies needs a clearer view on
LHC needs.
Discussion: Support from companies suffers from the fact that specs
have not yet been agreed on by the LHC community in any consistent way.
E.g.: protocols for voltage readout could be decided soon, as there is
no problem with bandwidth or any other critical parameter. Also experiments
could bundle their requests on HV-ranges and HV-current needs, to see whether
units can be designed for large volume production, satisfying many users.
Adolfo Fucci said that the ESS (electronics pool) would be ready to
take a coordinating role if there is sufficient input from the experimental
community. It was suggested that the power supply convenors of the experiments
undertake a new effort to evaluate the needs of the subdetectors.
It was also mentioned that there is potentially a large cost penalty
if decisions are delayed and standardisation is not achieved inside reasonable
limits.
R. Richter: Planning of the n-irrad. at PROSPERO, sept.
29/30
(As for the technical information this is partly a repetition of the
previous minutes.)
Sept., 29th: installation of test-equipment in hall, cabling to control
room, pre-rad tests.
Sept., 30th: irrad. (see below)
Working time at the site is 8:30h to 16:30h; it is not possible to
work at the site outside working hours.
All material will be controlled for activation after the irradiation.
Depending on dose and material's mass and composition, a cool-down of up
to a few days may be necessary. Cleared material will be sent to CERN by
mail. TIS says that military safty limits exceed CERN's so there will be
no problem for CERN rad-safety.
Cabling between hall and lab:
There is a patch-panel available with 13 BNC and 15 type C connectors
between hall and lab which can be used. There are also 2 DEUTCH connectors
with 37 pins. Length=24 m.
User-made cables:
Length: about 7 m in hall, 5 m in lab and 25 m in-between, therefore
35-40 m should be foreseen.
Diameter: ALL user-made cables have to go through a tube of 50 mm inner
diameter and about 3 m length (passage between hall and basement).
Flat-pack multi-twisted pair cables are most difficult to pass WITH
connector, therefore tools for putting connectors on AFTER passage should
be brought along, the same for LV-DC supply cables.
Power cables:
There is a sufficient number of power plugs (220 V) on the wall of
the hall. Remember swiss (CERN) plugs are incompatible with french plugs!
Dimensions of hall:
width 8m, length 10 m; reactor at 2.40 m from wall in longitudinal
direction, leaving 7.60 m to other wall. In other coordinate reactor is
at 4.2 m from wall. Maximum practical distance from reactor is about 6
m, corresponding to 2*10^11 n/cm^2/h at 100% reactor power.
Irrad. will proceed as follows:
1) 1 hour @ 50% reactor power, giving about 2*10^11 n/cm^2 at 3 m
2) pause of about 30 min for cool down and access for about 15 min to remove irradiated material
3) 5 hours @100%, giving 10^13 n/cm^2 at 1.5 m and 2*10^12 at 3 m
So the total duration is about 7 hours (9h to 16h).
Users can, of course, tune the dose by selecting the appropriate distance.
No access will be allowed during 2) for people without a MEDICAL EXAMINATION (blood test), so please do your routine check at CERN soon!
Participants in test:
Name
Institute Device under
test
Personal coord.
(brackets: passive test)
known for site
admittance
------------------------------------------------------------------------------------------------
V. Bartheld
MPI
ALMY sensors, (MDT tubes)
yes
H. v.d. Graaf
NIKHEF CCDs for RASNIK, DCS-LMBs
no
E. Marschalkowski Mainz
LAr electronics
no
G. Ielapi
Mainz
no
B. Hallgren
CERN
DCS-LMBs
yes
W. d. Sprolant
CERN LV-power supplies
yes
B. Allongue
CERN
yes
P. Farthouat
CERN
yes
R. Richter
CERN
yes
only passive test:
(K. Hashemi) Brandeis
(CCDs)
(R. Frei) Lausanne
(line drivers)
A photocopy of you passport should be FAXed to the following number:
from outside FRANCE: 0033-3 8023 5216
from CERN:
10-03 8023 5216
Please send it to Mr. Zyromski, referring to our test on sept. 29/30.
Please do this by sept., 7th, latest to be shure to get clearance for
the run. Remember: this requires 3 weeks of administrative work on which
the people at PROSPERO have no influence.
The site is located about 30 km north of Dijon and can be reached from Geneva in about 3 hours by car.
We will organise car transport from CERN.
Robert Richter