# Quality Checks

## Run Summary Table

The table below uses a characteristic DST file to try and estimate the sample size for a semi-inclusive analysis of pion electroproduction. The column marked "cuts" below indicates the number of events kept when the standard EC based electron identification cuts, described above, are used: and
. The next step will be to compare unpolarized pion production rates in order to evaluate the CLAS detectors efficiencies for measuring charged pions with different torus polarities. The question is whether you get the same rates for negatively charged pions in one torus polarity to positively charged pions using the opposite torus polarity.

Beam Energy Torus Current Target Begin Run End Run file used # trig() events remaining after cuts(%) expected # evts() events remaining after and cuts(%) expected # evts() events remaining after and cuts(%) expected # evts()
4239 2250 NH3 28205 28277 /cache/mss/home/nguler/dst/dst28205_05.B00 1108.72 60.8 674.1 8.3 92.02 3.24 35.92
ND3 28074 28190 /cache/mss/home/nguler/dst/dst28187_05.B00 1117.87 59.6 666.25 7.99 89.32 3.3 36.9
-2250 NH3 28407 28479 /cache/mss/home/nguler/dst/dst28409_05.B00 1013.57 24.2 245.28 0.12 1.22 0 0
ND3 28278 28403 /cache/mss/home/nguler/dst/dst28400_05.B00 1556.04 23.9 371.89 0.02 0.31 0.05 0.51
5735 2250 NH3 27074 27195 /cache/mss/home/nguler/dst/dst27095_05.B00 1442.25 57.7 832.18 9.3 134.13 3.8 59.13
ND3 27116 27170 /cache/mss/home/nguler/dst/dst27141_05.B00 624.55 59.1 369.10 9.53 59.52 3.9 24.36
-2250 NH3 26911 27015 /cache/mss/home/nguler/dst/dst26988_05.B00 900.93 80.7 727.05 7.14 64.33 9.9 89.19
ND3 27022 27068 /cache/mss/home/nguler/dst/dst27055_05.B00 711.53 80 569.22 6.97 49.59 10.1 71.86

## Rates

### Unpolarized Pion electroproduction

#### Rates from other experiments in our Kinematic range

##### Center of Mass Frame Transformation

We have proton and electron. In the Lab frame electron is moving along the x-axis with momentum ; and proton is at rest. The 4-vectors are:

Lab Frame
(,,0,0) and for proton :(,0,0,0)
CM Frame
:(,,,) and for proton :(,,,)
Find such that

Using the last two equations we will get the following for x component:

##### Example of the Missing Mass Calculation for the following reaction

: electron mass is neglibible
: Mass of a proton

Electron

Proton

Missing Mass
Conservation of the 4-momentum gives us following

Solving it for the final proton state

In our case 4-vectors for particles are

Plug and chug

] [ + - -

##### Example of the Missing Mass Calculation for the following reaction

Used file dst27095_05.B00. Target , Beam Energy 5.735 GeV and Torus Current +2250. Event_number=3106861

: electron mass is negligible
: Mass of a proton
: Mass of a neutron

Electron

Neutron

Missing Mass Calculation
Below is the conservation of the 4-momentum

Solving it for the final neutron state

The 4-vectors for the particles in this event

] [ + - -

##### Missing_Mass(experimental data)

The mean value of the missing mass is around 2.056 GeV.

##### angle
###### angle for electrons and pions () in lab frame ,
 Electron fiducial cut at electron momentum range : 2.15 < < 2.53 GeV for sector 1. The histograms on the right show the < distributions at two values of . The highlighted area in the center indicates the selected fiducial range. [1]

###### Phi angles

Below is shown histograms before changing angles by sectors for pions and electrons.

ELECTRON SECTOR vs ELECTRON ANGLE
dst27095_05.B00, B>0, target material NH3, Target Polarization (78.19) and Beam energy 5.7 GeV dst26988_05.B00, B<0, target material NH3, Target Polarization (-67.82) and Beam energy 5.7 GeV dst27109_05.B00, B>0, target material NH3, Target Polarization (-69.81) and Beam energy 5.7 GeV

ANGLE DISTRIBUTION FOR ELECTRONS AND PIONS(in each event we have just two particles eelctron and positive pion), FILE dst27095_05
ELECTRONS PIONS(prt_id=4)

SECTOR_VS_ FOR ELECTRONS AND PIONS, FILE dst27095_05
ELECTRONS PIONS(prt_id=4)

Graph  for Pions hitting paddle #7.  The y-axis should be pion counting rate in units of pions per nanCoulomb.

###### angle in the Center of Mass Frame

The variables below are in Lab Frame:

From from CLAS

 Kinematics of single electroproduction

From the above picture we can write down the momentum x,y and z components for pion in terms of angle and total momentum.

where and are the x and y components of the pion momentum.

- Initial electron 4-momentum
- Target Nucleon 4-momentum
- Scattered electron 4-momentum
- Meson final state 4-momentum

, for

In Inclusive

Then The Missing Mass

In Exclusive

Then Missing Mass

Conservation of 4-momentum gives

- 4-momentum of the exchanged virtual photon()

###### axis rotation

First the coordinate system is rotated around z-axis by angle and then around y-axis by angle. Below is presented the transformation matrix.

###### Phi rate
 |[3]Differential cross section vs in the region at fixed for different bins in

 start calculating cross -section

###### Luminosity Calculation for NH3(Ammonia) target

The target materials are located in the target cells. They are made out of polychlorotrifluoroethylene with a thickness of 0.2 mm. The cells itself are in diameter 15 (15.7) mm and in length 10 (12.7) mm, with 0.025 mm aluminum entrance windows and 0.05 mm kapton exit windows. [4]

Media:fill.factor.ps NH3 Filling Factor Evaluation, R. De Vita, July 1999

[5]
For file dst27095_05.B00 beam current is

electrons per second

The luminosity of the continuous electron beam was [7] [8]

Cross Section Calculation

where

is the Luminosity.
is the number of interactions.
is the total cross section.
is the differential solid angle.
is the differential cross section.

#### Pion Rates -vs- Paddle for opposite sign Torus fields

using all events in which the first particle (the one which caused the trigger) is defined as an electrons and passes the
##### sc_paddle vs X_bjorken 5.7 GeV Beam Energy
no cuts cuts no cuts cuts
Electrons B > 0 B<0
B > 0 B<0
B > 0 B<0
B>0 B<0
B>0 B<0
##### sc_paddle vs Momentum 5.7 GeV Beam Energy
There is a curvature problem.  When B > 0 then I expect the high momentum electrons to hit the lower
paddle numbers   (inbending).   I can see this when I look at the B>0 plot for electrons with cuts.
When B < 0 then the electrons  are bending outwards which makes me expect the the higher momentum
electrons will high the higher numbered paddles.  I do not see this for B>0 with electron cuts.

no cuts cuts no cuts cuts
Electons B > 0 B<0
B > 0 B<0

B > 0 B<0

##### sc_paddle vs Momentum with cuts 5.7 GeV Beam Energy(number of events=2)
B>0 B<0
B>0 B<0

Used file dst26988_05.B00(Energy=5.7GeV and Torus=-2250)

##### Paddle 7 Rates and statistics

The number of events per trigger is measured for the respective DST file above and then the Total number events in the data set is estimated from that.

(B>0) (B<0)
Total Number Events Number events per triggers Total Number Events Number events per trigger
0.1 5.1 71 24.6 547
0.2 6.9 96 13.7 305
0.3 3.7 51 6.2 137
0.4 3.3 45 2.7 60
0.5 0.9 13 0.99 22
##### Paddle 17 Rates and statistics
(B<0) (B>0)
Total Number Events Number events per trigger Total Number Events Number events per trigger
0.1 6.2 137 4.6 64
0.2 3.5 79 4.9 67
0.3 1.7 39 2.6 36
0.4 0.3 7 2.1 29
0.5 0.1 2 0.6 8
##### Paddle 5 and 8 Rates and statistics for electrons
Total Number Events Number events per trigger Total Number Events Number events per trigger
0.1 384.9 5.314 1665.2 3.706
0.2 382.5 5.282 977.8 2.176
0.3 264.9 3.657 567.1 1.262
0.4 159.5 2.202 328.6 0.7313
0.5 99 1.367 218.2 0.4856
##### Histograms for 5.7 GeV Beam Energy
Electron energy/momentum Electron Theta () Electron Qsqrd Electron X_bjorken