FORWARDS FIT

negative phi

(1) |

Ne = Number events/100000

4 layers in negative phi used to find values of D and C

X fixed =1

VAR | VALUE | ERROR | |

D1 | 12.9681 | 0.843960 | |

D2 | 31.4216 | 1.19890 | |

D3 | 27.1672 | 1.10404 | |

D4 | 5.55769 | 0.564706 | |

C1 | -8.75987 | 0.962665 | |

C2 | -19.2786 | 1.37036 | |

C3 | -14.2078 | 1.26846 | |

C4 | -1.07452 | 0.655159 |

see attachments below ForwardsFitNegPhi.eps

C negative (not exactly what want) But this shows that range |Eta|<1 material varies as 1/sin Theta

Then in positive phi

add linear term to X

To account for extra material of 0.5-1.5% Interaction lengths in SCT2

Fix Ds and Cs

VAR | VALUE | ERROR |

m | 0.0782631 | 0.0115899 |

c | 0.0366751 | 0.0661413 |

see attached nModmEtaPlusc.pdf

4-12% extra ??

(~4% at eta =0 increasing to ~12% at |eta|=1)

This does not take into account brem seen in next layer.

Ntuple kindly sent from Pat Ward: Mean number interaction lengths traversed by particle through SCT barrel. I fitted 8/sinTheta - could then presume each SCT layer contributes 2% interaction lengths

see SCTInteractionLengths.eps

OR

If consider each SCT layer has silicon thickness 285 microns ~0.61% radiation lengths ~ 3% interaction lengths

(Silicon radiation length 21.82 gcm-2, nuclear interaction length 108.4gcm-2)

So my 4% extra material seen at eta=0 corresponds to 4% of 2.5% = 0.1% interaction length

(Expecting 0.5% interaction length which corresponds to 1% radiation length carbon))

I said it wasn't clever!

Oh. And you know its in SCT 2 because when you look at Backwards fit, it totally obvious.

see attachments below

-- SueCheatham - 9 Sept 2009

I | Attachment | History | Action | Size | Date | Who | Comment |
---|---|---|---|---|---|---|---|

eps | ForwardsFitNegPhi.eps | r1 | manage | 53.1 K | 2009-09-09 - 20:01 | SueCheatham | Negative Phi SCT layers fitted with 1/sinTheta. Same fit shown on positive phi |

eps | NumberHitsSCT.eps | r1 | manage | 53.3 K | 2009-09-09 - 20:18 | SueCheatham | Number of hits in positive phi clearly more than in negative phi |

eps | NumberHitsSCTBackwards.eps | r1 | manage | 50.6 K | 2009-09-09 - 22:30 | SueCheatham | Backwards Fit |

eps | SCTInteractionLengths.eps | r1 | manage | 13.1 K | 2009-09-10 - 00:06 | SueCheatham | SCT material budget in interaction lengths |

nModmEtaPlusc.pdf | r1 | manage | 26.2 K | 2009-09-09 - 20:03 | SueCheatham | Parameters from negative phi fit fixed. Linear term added to positive phi to account for extra material. |

Topic revision: r7 - 2009-10-13 - SueCheatham

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