The first look at sagitta resolution vs momentum

(F. Cerutti –E. Meoni –S. Rosati - A. Policicchio- S. Ventura)First measure of sagitta resolution on barrel and beam momentum for a data set

Operating conditions: Energy beam 250 GeV, MDT Main Ths -40mV- Trigger 10X10 –

BIL Rot ON/OFF- Magnet current 0A/600 A

Run number: 600681(73Kevt) – 600682(97Kevt) – 600722(30Kevt)-600723(50Kevt)- 600724(32Kevt)- 600725(71 Kevt)

In particular: 600724 MBPL magnet at 600A BIL rotation OFF (P and sagitta measur.)600725 MBPL magnet at 0A BIL rotation OFF (Alignment BIL rot. vs. Barrel )

T0 fitsBIL rot ml=1 mezzanine=2BIL2 ml=2 mezzanine=2

BML2 ml=2 mezzanine=2 BOL2 ml=2 mezzanine=3

T0 fits computed grouping TDC spectra of channels inthe same mezzanine

Fermi-Dirac distribution

Applied a cut on ADC counts:accepted hits withADC > 45

Residual Distributions

BIL rot ml=1 BOL2 ml=2

mm

mmmmmm

R-T relation produced by Rome3 with calib for the run 600379:BIL Rot ON, ± 10degree, 18 June.(for drift distences smaller than 2mm used a linear r-t relation)

Events reconstructed with athena 8.5.0

Systematic error at level of 50m related to temperatureeffects and t0 effects

mm

mm

BIL2 ml=1 mm

mm

Barrel sagitta

mm

BOL

BML

BIL

Selected track segments in the jura-side chambers (most illuminated)

Sigma 68 m

Beam Profile on RPC phi-strips

BML2 rdoublr=1 BML2 rdoublr=2

We select the most illuminated phi-strips: at least one hit in this strip for RPC rdoublr=1 (behind the MDT)and one for RPC rdoublr=2 (beyond the MDT) in BML station.

P measurement B(600A) B(0A)

Momentum

GeV

)0,()600,()(3.0)(

ABABTmBLGeVP

entbilrotsegmentbarrelsegm

Mean=233 GeVSigma=15 GeV

BL=3.54 Tm

Sagitta Distribution (RPC cuts + Pcut)

ooo XxXxp ln0038.01MeV6.13 osm ZZ

ZZZZS tan13

2312..

Multiple scattering contribute to sagitta resolution:

For p=233 GeV (Sms)=29 m

Sigma 63 m

P > 215 GeV

mSSS msmeasi 56)()()( 22

mm

Final observation…

Phi-strip position (mm)

Sagi

tta(

m)

The mean value of the sagitta has a maximum spread of 2.5 m on four phi-strip (the most illuminated ones) …….we can remove RPC cuts onour study