Qweak Delta

Expected results

The above Figure in EPS format :File:D Delta Qweak Error.eps

File:A d-delta-vs-Q2.xmgrace.txt

The above Figure in EPS format :File:Atot d Delta Qweak Error.eps

File:Atot d-delta-vs-Q2.xmgrace.txt

Media:LOI-03-105.pdf

Media:PCS_Report_4_LOI-03-105.pdf

Katherine's Table

Ratio of Elastic to Inelastic Region Rates = [math]\frac{650 MHz}{20 MHz + 50 MHz}[/math] = 9.3:1 = Rate ratio for QTOR=100% / 75%

In the denominator 20 MHz = Inelastic rate and 50 MHz is the elastic rate; according to the simulation

Elastic Aluminum Asymetry

The Aluminum asymmetry was measured to be [math]1.61 \pm 0.16[/math] PPM

0.2 MHz/nA using warm gas target

Warm gas contribution about same size as downstream aluminum window.

To do aluminum measurement we can't use warm gas cell.

Aluminum window dilution 0.022+/- 0.002

Transverse Aluminum in Elastic

A sin wave with amplitude of about 4 PPM

You can weight the yields so the transverse asymmetry gets averaged over all octants.

File:Shi-Lin Zhu hep-ph-0107076 2001.pdf

first Inelastic Data

Asym -vs- QTOR

From Logbook entry https://qweak.jlab.org/elog/Analysis+%26+Simulation/254

The inelastic region of interest is expected to line up o the quartz bars when QTOR ~ 0.85 of its value for elastics.

In Feb 2011, QTOR(elastic) = 8921.

=> QTOR(Delta) = 0.85 \times 8921 = 7582

Run 9908

1 hour run with HWP OUT

https://hallcweb.jlab.org/hclog/1102_archive/110211010249.html https://hallcweb.jlab.org/hclog/1102_archive/110211020513.html

Run 9905

1 hour run with HWP IN

https://hallcweb.jlab.org/hclog/1102_archive/110210233842.html https://hallcweb.jlab.org/hclog/1102_archive/110211002416.html

Combining 2 hour of data taking

QTOR= 6700 Amps

I_{beam} = 145 \mu A

[math]A_{raw} = 1.296 \pm 0.579[/math]= Asymmetry averaged over all Main Detectors

If I assume only having 50 \mu A then I would need to take 6 hours of data to get the same statistic as above.

If I take a week of data at 50 \muA then that would correspond to 28 runs like the above.

So the uncertainty would be reduced by [math]\sqrt{28} = 5.29[/math] The measurement would have an uncertainty of 0.579/sqrt{28} = 0.1 PPM

background

Dave Mack's technical note on Qweak Background contributions and propogating their error. File:Qweak Doc 965 v1.pdf

Regression

https://qweak.jlab.org/wiki/index.php/Q-weak_Regression_Wiki_Page

Data Analysis

getting Qweak data from the Silo

jcache -g hallc /mss/hallc/qweak/rootfiles/pass0/*run number here*

looking for GOOD runs in database

There is a GUI interface on cdaql4 which can be run to look at run numbers and see their quality as recorded in the data base.

On cdaql4 run

./good_for_GUI

Root file format

The Qweak root files contain 2 trees ( MPS_Tree and EL_Tree). As the names suggest, the MPS tree contains data from devices for each Helicity bin. The HLS tree constructs helicity differences and asymmetries for each device in the data stream.

The devices listed in each tree above are folders which have sorted the data into 4 time windows within the helicity gate.

In the MPS_Tree there is a Bock0, Block1, Block2, Block3.

Drawing tree elements

Mps_Tree->Draw("qwk_bcm1.hw_sum","ErrorFlag==0")

If you get an error try

.ls

or try going up to the file subdirectory

if you pass the filename on the command line then the file is opened under the name file(0) so

_file0->cd()

should take you to the main subdirectory.

I think using the old TBrowser(0 screws up the pointers. "cd" to the file pointer when that happens.