Difference: L0ConfHCalAndTStations (6 vs. 7)

Revision 72006-06-08 - MalcolmJohn

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META TOPICPARENT name="HadronAlley"

L0 Confirmation using the T stations (Hadron alley)

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  On the use of S-curve corrections in the ECAL
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First a decision has to be made on the theshhold above which we assume the energy deposit in the ECAL is associated to the hadron shower. As a guide, we look at the S-curves in the ECAL as a function of energy (not E_T!) cut-off. Where no cut-off is applied, additional energy is seen occuring on only one cell. Visually this 'noise' is represented as tails away from the S-curve. These tails are seen to reduce with large cut on the ECAL energy deposit considered.
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As above, an s-Curve correction can be applied. The parameters and observed improvement are recorded in the following table.
 
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  • S-curves (y_rec vs. y_mc) for a 2x2 cell group from the inner ECAL. Four energy threshholds shown.:
    S-curves (y_rec vs. y_mc) for a 2x2 cell group from the inner ECAL. Four energy threshholds shown.
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  inner ECAL middle ECAL outer ECAL
  x y x y x y
A 8.3 9.3 13 13 22 22
B 0.063 0.063 0.042 0.040 0.021 0.021
C -1.3(l)/1.8(r) -1.0(u)/1.1(l) -3.0(l)/1.1(r) -1.7(u)/0.6(l) -6.7(l)/3.7(r) -2.0(u)/-1.1(l)
RMS (before) 16.6 16.7 21.7 20.6 42.3 41.0
(after) 16.5 16.4 21.3 20.1 41.4 39.9
sigma (before) 9.5 9.2 14.3 13.6 28.0 27.7
(after) 8.7 8.6 12.7 12.1 22.0 21.5

The corrective effect of the S-curve correction is can be visualised here: (before correction), (correction applied).

Finally a decision has to be made on the theshhold above which we assume the energy deposit in the ECAL is associated to the hadron shower. As a guide, we look at the S-curves in the ECAL as a function of four energy (not E_T!) cut-offs. To partially remove the noise tails seen at the edges of the curves, a energy cut of 1000MeV and 500MeV is applied for the inner and middle part of the ECAL. No cut is deemed necessary for the outer part.

Predicting the particle track into the T-stations

To predict the track of the L0 Candidate, it is assumed the particle has followed a straight line from the IP (0,0,0) in y. For x, the deviation from a straight line due tothe magnetic field is assumed to be inversely proportional to the particle's energy. See the following sketch by Herve...

magFieldParam.jpg

The parameter "alpha" is obtained from a 350k minimum bias Monte Carlo sample and is recorded in the following table:

x10^6 T1 T2 T3
IT OT IT OT IT OT
HCAL 2.80 2.78 2.52 2.47 2.21 2.15
ECAL 2.56 2.52 2.25 2.20 1.92 1.85
 
META FILEATTACHMENT attr="h" comment="S-Curves for the HCAL" date="1149702268" name="sCurveHcalBefore.gif" path="sCurveHcalBefore.gif" size="10204" user="mjohn" version="1.1"
META FILEATTACHMENT attr="h" comment="S-Curves for the HCAL (correced)" date="1149702242" name="sCurveHcalAfter.gif" path="sCurveHcalAfter.gif" size="13003" user="mjohn" version="1.1"
META FILEATTACHMENT attr="h" comment="1st line :Before... 2nd line: After correction" date="1149703359" name="sCurveHcalImprovement.gif" path="sCurveHcalImprovement.gif" size="13253" user="mjohn" version="1.1"
META FILEATTACHMENT attr="h" comment="S-curves (y_rec vs. y_mc) for a 2x2 cell group from the inner ECAL. Four energy threshholds shown." date="1149788053" name="sCurveVsEthreshhold.gif" path="sCurveVsEthreshhold.gif" size="16153" user="mjohn" version="1.1"
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META FILEATTACHMENT attr="h" comment="ECAL sCurves (before)" date="1149794054" name="sCurveECAL_before.gif" path="sCurveECAL_before.gif" size="15159" user="mjohn" version="1.1"
META FILEATTACHMENT attr="h" comment="ECAL sCurves (after)" date="1149794086" name="sCurveECAL_after.gif" path="sCurveECAL_after.gif" size="15358" user="mjohn" version="1.1"
META FILEATTACHMENT attr="h" comment="" date="1149800384" name="magFieldParam.jpg" path="magFieldParam.jpg" size="38559" user="mjohn" version="1.1"
 
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