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e661d480 | 1 | The Offline Condition DataBase is described extensively on ALICE Offline pages. |
2 | ||
3 | Here you'll find only information relevant to the MUONCDB.C macro, which defines | |
4 | a set of functions to read/write MUON information to this CDB. Those functions are | |
5 | not meant to be used as black boxes. Please have a closer look before using | |
6 | (especially the ones writing to the CDB...) | |
7 | ||
8 | ------- | |
9 | Calibration data objects | |
10 | ------- | |
11 | ||
12 | We've designed generic data containers to store calibration information, | |
13 | tailored to the way we usually access MUON tracker data, that is, indexed by the pair (detElemId,manuId). | |
14 | This container is called AliMUONV2DStore. You can attach a TObject to every and each pair (detElemId,manuId). | |
15 | For the moment, that TObject is generally of AliMUONVCalibParam type, | |
16 | which handles a given number of channels (64 typically) as a group. | |
17 | As the class names suggest, both classes are only interfaces. Concrete ones are AliMUON2DMap (used instead of a vector | |
18 | as detElemId are not contiguous) for the V2DStore, CalibParam1I (VCalibParam storing one integer per channel), and | |
19 | CalibParam2F (VCalibParam storing 2 floats per channel). | |
20 | ||
21 | One exception are the HV values from DCS, which are stored "as they come" from the shuttle-dcs interface, as a TMap, where | |
22 | the key is the aliasname (TString), and the value a TObjArray of AliDCSValue. | |
23 | ||
24 | For trigger, the same virtual container idea applies, except we're using 1D container (AliMUONV1DStore). | |
25 | ||
26 | -------- | |
27 | CDB location | |
28 | -------- | |
29 | ||
30 | One very important notion is that of the DefaultStorage (which you set with | |
31 | AliCDBManager::Instance()->SetDefaultStorage(path)), which tells the CDB library where | |
32 | the CDB is sitting (either locally on disk, or on the grid). | |
33 | ||
34 | For local tests, path will be most likely = local://$ALICE_ROOT/MUON (i.e. there is, in CVS a slim version of the calibration objects needed | |
35 | for running the MUON code), or local://$ALICE_ROOT/SHUTTLE/TestShuttle/TestCDB for Shuttle testing. | |
36 | ||
37 | ------- | |
38 | Writing to CDB | |
39 | ------- | |
40 | ||
41 | In write mode, this macro was/is used to populate the CDB with fake calibration objects for testing purposes. | |
42 | Real calibration data will normally be handled by the Shuttle (see READMEshuttle). | |
43 | ||
44 | writeGains() and writePedestals() functions may be used to populate MUON tracker information, | |
45 | and generateTrigger() for trigger parts. | |
46 | ||
47 | ------ | |
48 | Reading the CDB | |
49 | ------ | |
50 | ||
51 | The actual reading is encapsulated into AliMUONCalibrationData class. | |
52 | e.g. to read pedestals for run 4567, one would do : | |
53 | ||
54 | AliCDBManager::Instance()->SetDefaultStorage(cdbPath); | |
55 | AliMUONCalibrationData cd(4567); | |
56 | AliMUONV2DStore* ped = cd.Pedestals(); | |
57 | ||
58 | If you want to plot calibration data (not terribly usefull as it's a really global view), use the plot() function | |
59 | in MUONCDB.C, e.g. : | |
60 | ||
61 | plot(*ped,"pedestal") | |
62 | ||
63 | which will create 2 histograms : pedestal_0 (mean) and pedestal_1 (sigma). | |
64 | ||
65 | You might also be interested in the diff() method which generates an AliMUONV2DStore | |
66 | containing the difference (either absolute or relative) of two AliMUONV2DStore. | |
67 | ||
68 |