ALICE Calibration Requirements |
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TPC July 18 |
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Par # |
Parameter |
Data format/size
per channel |
Data size (Total)
Bytes |
Update freq |
Source |
Confirmed |
Run type / Trigger type |
# of required
events/sampling rate |
Processing
level: sub-event or event |
Results:
FEE/Archive |
Accessible by offline |
Calib. Procedure in AliRoot[1] |
use
case # |
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on FES |
in OCDB |
reference |
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Pad by pad calibration |
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1 |
Pedestal ALTRO |
1K (Time bin)
x10b value per pad |
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0 |
7.00E+08[2] |
run |
DAQ or HLT
(+Offline check) |
yes ? (Roland, Marian) |
Dedicated run
(with pedestal) |
100 black events |
Configure FEE through DIM/DDL.
Stored on pedestal file server(?) migrated to CASTOR. The pointer to the
Castor file is stored in DAQ Logbook. |
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no |
- |
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2 |
Pedestal |
4 By - one value per pad |
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2.40E+06[3] |
4.46E+08[4] |
run |
DAQ or HLT
(+Offline check) |
yes ? (Roland, Marian) |
Dedicated run (with
pedestal) |
101 black events |
subevent
(DAQ) |
DAQ or HLT FES / OCDB |
yes |
algorithm - rec usage - rec |
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3 |
Noise |
4 By - one value per pad |
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2.40E+06[5] |
run |
DAQ or HLT
(+Offline check) |
yes ? (Roland, Marian) |
Dedicated run (with
pedestal) |
102 black events |
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DAQ or HLT FES / OCDB |
yes |
algorithm - rec usage - rec |
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4 |
Gain calibration
of electronics |
4 B/channel |
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2.40E+06 |
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LHC period |
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yes ? (Roland, Marian) |
Pulser run |
- |
subevent
(DAQ) |
DAQ FES/ OCDB |
yes |
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5 |
Timing alignment
of electronics |
4B/channel |
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2.40E+06 |
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DAQ/HLT(Offline
check of algorithm) |
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Dedicated run (with pedestals) |
100 black events |
sub-event |
DAQ/HLT FES/ OCDB |
yes |
usaage -rec
01.09.06 |
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6 |
Gain calibration-per
pad or per group |
4 B/channel |
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2.40E+06 |
4.46E+08[6] |
month |
Offline |
yes ? (Roland, Marian) |
physics run |
1e6 pp events (minimal) 1e8 pp events |
- |
OCDB |
yes |
usage: sim
and rec |
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2.40E+06 |
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Offline |
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physisc run |
1e4 pp events |
- |
OCDB |
yes |
usage: sim
and rec |
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7 |
Tail
cancellation (CoG change) |
4Bx6(Parameters) |
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[7] |
1.30E+07[8] |
Rare |
Offline |
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Physics run (Black events) |
selected pulses out of 10M pp events (100TB) |
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OCDB |
yes |
Not needed
for reconstruction. CoG might be needed, but not yet clear |
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DCS values |
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6 |
Temperature
probes |
8B/channel |
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1.00E+06[9] |
DCS update
frequency ~0.1 Hz |
minute ( defined by deadband in compression ) |
DCS |
30/10/06 |
- |
- |
- |
DCS ArchiveDB/OCDB |
yes |
01.05.07 |
4 |
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7 |
Temperature
probes (FEC) |
8B/channel |
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1.00E+06[10] |
DCS update frequency ~0.1 Hz |
10 minutes (
defined by deadband in compression ) |
DCS |
30/10/07 |
- |
- |
- |
DCS
ArchiveDB/OCDB |
yes |
01.05.07 |
4 |
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8 |
Pressure |
4By
atmospheric pressure + 4By overpresure |
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1.00E+04[11] |
DCS update frequency ~0.1 Hz |
10 s (
defined by deadband in compression ) |
DCS |
30/10/08 |
- |
- |
- |
DCS
ArchiveDB/OCDB |
yes |
01.05.07 |
4 |
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9 |
Drift velocity monitor (Goofie) |
8By |
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200[12] |
- |
20 minutes |
DCS |
30/10/09 |
- |
- |
- |
DCS
ArchiveDB/OCDB |
yes |
01.05.07 |
4 |
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10 |
Gas gain 0, 1 (Goofie) |
8By |
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400[13] |
- |
DCS |
30/10/10 |
- |
- |
- |
DCS
ArchiveDB/OCDB |
yes |
01.05.07 |
4 |
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11 |
Gas composition (Goofie) |
8By (CO2 and N) |
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400[14] |
- |
DCS |
30/10/11 |
- |
- |
- |
DCS
ArchiveDB/OCDB |
yes |
01.05.07 |
4 |
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12 |
Gas composition
(Analyzer) |
8By (O2, H2O and CO2) |
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600[15] |
- |
DCS |
30/10/12 |
- |
- |
- |
DCS
ArchiveDB/OCDB |
yes |
01.05.07 |
4 |
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13 |
Chamber - HV
(Current) |
8By |
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5.00E+05[16] |
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DCS |
30/10/13 |
- |
- |
- |
DCS
ArchiveDB/OCDB |
yes |
01.05.07 |
4 |
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14 |
Chamber - HV
(Voltages) |
8By |
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5.00E+04[17] |
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DCS |
30/10/14 |
- |
- |
- |
DCS
ArchiveDB/OCDB |
yes |
01.05.07 |
4 |
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15 |
Drift - VHV
(Current) |
8By |
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2.00E+03[18] |
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DCS |
30/10/15 |
- |
- |
- |
DCS
ArchiveDB/OCDB |
yes |
01.05.07 |
4 |
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16 |
Drift - VHV
(Voltages) |
8By |
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200[19] |
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DCS |
30/10/16 |
- |
- |
- |
DCS
ArchiveDB/OCDB |
yes |
01.05.07 |
4 |
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Data stream and event trailer |
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1 |
Moving average
& zero suppression state ON/OFF |
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1 |
- |
Rare |
Event trailer |
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Dedicated run |
1-10 black events |
sub-event |
- |
yes |
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2 |
ALTRO frequency |
1 value/detector |
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- |
- |
Rare |
Event trailer |
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- |
- |
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yes |
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3 |
ALTRO
acquisition window |
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- |
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pp/HI |
Event trailer |
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- |
- |
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yes |
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state pp/HI |
1 value/detector |
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1 |
- |
pp/HI |
Event trailer |
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- |
- |
- |
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yes |
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4 |
Active channel
list |
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- |
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Data stream |
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- |
- |
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yes |
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Space point corrections |
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1 |
Drift velocity
map |
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1.00E+06 |
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Rare |
Offline |
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- |
- |
- |
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2 |
ExB map |
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1.00E+06 |
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Rare |
Offline |
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Dedicated runs with laser for
various value of B |
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3 |
Space charge map |
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2.00E+06 |
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Offline |
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2.04E+07 |
1.61E+09 |
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TPC calibration |
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Raw DATA volume: |
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Black
event : |
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Number of pads x number of
time bins x 10 bit |
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557568x1Kx10b ==> 700 MB |
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Zero suppressed event: |
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1
MBy (pile-up of 5 events – ALICE
Computing TDR) |
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…. |
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Events per year ~ 10^9
pp |
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Size of histograms pad x pad
calibration : |
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557568
pads x 100 bins (non equidistant binning) x 2By ~ 111 MBy |
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Histograms stored in CDB |
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Calibration per pad: |
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Nevents
x Ntracks x Nrows/Npads = X |
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Nevents
– Number of events to get statistic X for pad calibration |
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Ntracks
– number of tracks per event – for pp ~ 8 |
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Nrows - number of rows per track ~ 150 |
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X - required statistic per pad
calibration |
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Nevents
= X x (Npads/ (Ntracks*Nrows)) ~ X x 500 |
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--------------------------------------------------------------- |
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Nevents
x Ntracks /(Npadsmax*NSector) = X |
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Npadsmax
– maximal number of pads per row ~ 140 |
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NSectors - 36 |
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Nevents
= X x (Npadsmax*NSector/Ntracks) ~ X x 630 |
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Calibration per bin (pad –
pad row grouping): |
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Nevents
x Ntracks x Nrows / (Nbinspad x Nbinspadrow x Nsectors) = X |
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Nbinspad ~ 10 |
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Nbinsrow ~ 10 |
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Nsectors 72 |
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Nevents
= X x (Nbinspad x Nbinspadrow x Nsectors)/
(Ntracks x Nrows) ~ X x 6 |
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Gain Calibration (pad by
pad): |
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Needed statistic determined
by required precision of gain calibration ~ relative uncertainty 3 sigma ~ 1 % |
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Lwidth
- Relative width (sigma) of landau distribution ~ 30 % |
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W =
Lwidth/sqrt(X) |
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Number of points in
histogram X ~ 1000 Landau distribution of amplitudes |
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Minimal Required number of events ~
0.5 x10^6 pp events |
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Source : OFFLINE,
HLT (?) |
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Algrithm: |
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OFFLINE histograming of normalized amplitude
spectra (Normalization to the track length). Postprocessing of ESD files
after reconstruction. |
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Gain calibration with Kr,
another possibility. |
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Calibration of parameters for
tail cancellation: |
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Needed statistic determined
by required precision of gain calibration ~ 5 % -W |
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Pwidth
- Relative width of Gaussian distribution ~ 20 % but + outliers |
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W =
Pwidth/sqrt(X) |
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Number of points in
histogram X ~ 50 (Gaussian distribution of values) |
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Cuttof
factor - only signal over threshold ~ 150 ADC ~ 20 |
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Pad by
pad: |
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Required number of events
~ 0.5 x10^6 pp black events |
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Data
volume to process ~ 10^3 TBy |
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Pad grouping: |
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Required number of events
~ 0.5 x10^4 pp black events |
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Data
volume to procces ~ 10 TBy |
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Source : OFFLINE |
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Neccesity of pad- by pad
calibration will be tested during TPC commisioing with laser pulse. |
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Defualt approach – calibration
for group of pads |
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Algorithm: |
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Update frequency: year
(voltage setting, gas mixture) |
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Sim rec - NO |
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DCS values: |
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Array of pair of time
stamps, values |
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Maximal writing rate : 1 Hz,
precision of time stamp value -1 s |
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Reading rate from DCS
database: ~ 1000 values per second |
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Data size: 8 Bytes per entry pair (time stamp, value) |
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Update
frequency: Defined by interpolation precision – deadband in DCS, highest frequency ~ 1 Hz. |
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Deadband
defined as critical change of the current measured value in respect with
previously stored one. |
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CDB storage: Graph of DCS
values (value, time stamp), respectively fitted values (linear or parabolic
fit for a range of time) |
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Temperature probes: |
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Deadband
value: Required precision ~ 0.05 C, The accuracy of temperature measurement ~
0.05 C |
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Update frequency: |
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10 s update frequency in DCS (minimum is 5
second) |
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1
minutes for offline |
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500
channels - No deadband
used. Old/New comparison (exact
matching). |
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5 sensors
for chamber x 36 |
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6x 18 –
outer cylinder |
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6 x 2 +
inner cylinder |
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2 x
12 - conical section |
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44 - inside
conical volume |
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4500
FEC channels: Deadband precision ~ 0.1 C |
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Depends on the resolution of
temperature sensors and on the variation of temperature during day. Day variation, switch on-off detector
electronic (~ 1 degree ?). To be compressed (fitted) on minute level in
Shuttle. |
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Source: (DCS Archive DB)
temperature probes |
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Number of channels
(sensors): ~ 4500 FEC and ~ 500 distributed on the surface of detector. |
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Expected data volume per
run: 5000(sensors) x 4 (hours) x 60 (minutes) x 8 Bytes (9MBy) |
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Reading time from DCS: 20
min |
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Pressure probes: |
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Deadband
value: Defined by required precision of drift velocity correction, and gas
gain correction ~ 0.1 mbar |
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Wd
~ E/p |
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Townsend coefficient alpha =
f(E/p) |
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Typical
variation of gain ~ -0.3 % per mbar |
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Deadband
value: 0.1 mbar |
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Update
frequency: Defined by deadband value and by variation during day (~ 15
mbar), minimum ~ 10 s |
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DCS - defined only by deadband value 0.1 mbar |
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Offline
– combination of deadband around linear fit |
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Source: DCS, pressure probes |
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Number of channels: 2 |
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1 – atmospheric pressure |
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2. -
overpressure |
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Expected
data volume: ~ kBy per run |
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Reading time from DCS:
bellow 1 s |
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GAS composition & Drift velocity monitor: |
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Deadband
value: |
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Analysers:
CO2: 0.1% deadband, update frequency according to this. |
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O2,
H2O: 1 ppm deadband |
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Goofie:
Update frequency: ~20 min |
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Values: Vd, Gain1, Gain2, CO2, N2, Pressure,
Temp, Time stamp. |
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No
deadband – |
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Vd - precision ~0.05% |
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Gain1 and Gain2 ~ 0.1 % |
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Co2 and Nitrogen content calculated form
vd and Gain (corrected for pressure and temperature) precission ~ 0.1 % |
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DCS - not yet connected |
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Number of channels: 1 - CO2 content – CO2 analyzer |
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Deadband
value: relative 10^-4 – too optimistic
– what is the resolution? |
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I will put
there +-3 sigma of resolution |
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Expected
data volume: ~ kBy |
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Expected
data volume: ~ kBy |
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High voltage (HV - ISEG): |
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Source: DCS |
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OFFLINE usage: monitoring |
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Number of channels: three
per sector |
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Dead band value: |
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New value on change,
Frequency 1 Hz |
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Required precision |
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Voltage: minimum step of
power supply ~ 0.5 Volt |
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Current:
~ resolution 4 nA |
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Update frequency: voltage ~
run |
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Current ~ ? |
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Expected data volume: |
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Number of
samples * Nchannels |
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Very High voltage (VHV): |
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Source:
DCS (Joachim) - Heinzinger |
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Number of channels: 1 |
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Deadband
value: |
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Measured precision ~ 10
bits ? |
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Required precision |
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Voltage: relative change
(reproducibility) ~ 10 ^-3 |
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Stability ~ 10^-5 |
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Mesurement ~ 10^-4 |
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Current: relative change
~ 0.01 |
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Update frequency: voltage ~
run |
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Current |
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Expected data volume: |
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Number of
samples * Nchannels |
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