# Presentation: 860498

## PNN2 Beam Background

- Benji Lewis
- Department of Physics & Astronomy
- University of New Mexico

- 3 May 2006
- PNN2 Analysis Meeting

## 1-Beam

- Backgrounds
- K+ decay in flight
- Beam 
- 1-Beam Sample
- Select  in B4
- Reverse B4DEDX (*b4abm_atc* < 1.0)
- Measure Rejection of *DELCO*
- E787-PNN2 used *DELCO*-6
- E949-PNN1 used *Delc* (nominally *DELCO*~2)
- Currently using PNN1-*Delc* cut to prevent looking in box.

## 1-Beam Rejection Bifurcations

- Loosen Cuts in an attempt to get more statistics

- Select incoming 

- Measure Rejection of *DELCO*

**branch #1**

**branch #3**

**branch #2**

## 1-Beam Normalization

- Invert *DELCO*

- Simple method:
- Invert measured cut and apply all other cuts.

**Branch #1**

## 1-Beam Normalization

- Apply setup cuts

- Invert *DELCO*

- Remove ’s from K
- Remove K’s from 

- bifurcate

- PNN2 are limited in statistics
- in the -bifurcation.

**branch #3**

**branch #2**

**branch #4**

**branch #5**

## 1-Beam Background

- Used DELC (~2ns), in final will use DELCO~6ns
- Values reported are scaled to 3/3 sample.
- Additional documents
- PNN2 (cpi-veto + ps16) _bmbkg___tables_pnn2.__pdf_
- PNN2 (cpi-veto only) _bmbkg___tables_pnn2cpi.__pdf_
- PNN2 (cpi-veto+ps16 using only e949 cuts) _bmbkg___tables_pnn2e949.__pdf_
- N1BM = 0.00210 ± 0.00210 (with CPI-veto online bit applied)
- N1BM = 0.00040 ± 0.00040 (all PNN2 triggers)
- E949-PNN1:  N1BM = 0.00383 ± 0.00236
- E787-PNN2:  N1BM = 0.00166 ± 0.00166
- Small, consistent with e949-PNN1 & e787-PNN2
- -branch bifurcation in Normalization has no events left.
- Use Branch 1 (no bifurcation), i.e. apply all cuts & invert *Delc*.
- Unable to verify normalization as PNN1 was able to do.
- PNN1: Branch 1 was consistent with norm. results from Branches 2-5
- Satisfied with results for now.

## 2-Beam

- Background
- KK type
- K++ K+ decay in flight
- Ktype
- K++ Beam 
- Rejection Sample
- Obtain events with beam particles entering at decay time.

- Obtain KK’s by removing K’s
*Cpitrs*Cpitail*
- B4DEDX (cut ’s)
- Measure Rejection of
*BWtrs*Cktrs*Cktail*

- Obtain K’s by removing KK’s
*Cktrs*Cktail*
- B4DEDX (cut K’s)
- Measure Rejection of
*BWtrs*CpiTRS*CpiTAIL*

## 2-Beam Rejection Bifurcations

- Remove Ke4, multiple body decay by inverting *TARGF*
- Tag two beam events in B4

- Select KK events by removing K
- Select K events by removing KK

- Measure Rejections

**branch #1**

**branch #2**

## 2-Beam Normalization Bifurcations

- Select KK events by requiring a hit in either BWTRS or Ck
- Select K events by requiring a hit in either BWTRS or C.
- LOOPHOLE!!!
- If an event has a BW hit w/o a hit in Ck or Cpi, then double counting will occur.

- Double counting not big effect in PNN1, due to higher statistics.

**branch #3**

**branch #4**

**branch #2**

**branch #1**

## PNN2 Trigger

- Problem for 2-BM K sample.
- We are able to correctly measure rejection of *CpiTRS* offline if we require
- Use ps16 sample for the K bifurcation.

## 2-Beam Background

- Values reported are scaled to 3/3 sample.
- KK
- N2BMkk = 0.139 ± 0.098 (with CPI-veto online bit applied)
- N2BMkk = 0.139 ± 0.099 (all PNN2 triggers)
- E949-PNN1:  N2BMkk = 0.000983 ± 0.000983
- E787-PNN2:  N2BMkk = 0.1459     ± 0.1459
- K
- N2BMkp = 0.898     ± 0.740     (with CPI-veto online bit applied)
- N2BMkp = 0.00884 ± 0.00720 (all PNN2 triggers)
- E949-PNN1:  N2BMkk = 0.000106 ± 0.000106
- E787-PNN2:  N2BMkk = 0.0197     ± 0.0197
- Too Large!!!
- KK is x140 larger than PNN1, consistent with e787-PNN2.
- K  is x80 (x8000) larger than PNN1, consistent with (larger than) e787.
- Determine cause of large increases (May 20th).

## Built automated scripts.
Obtain latest & greatest cuts that have been optimized by other studies.
Much less overhead and removes the need to relearn scripts a months later
Reproduced Jingliang’s e949-PNN1 study.
Additional document bmbkg_tables_pnn1.pdf

- Obtain latest & greatest cuts that have been optimized by other studies.
- Much less overhead and removes the need to relearn scripts a months later
- Reproduced Jingliang’s e949-PNN1 study.
- Additional document _bmbkg___tables_pnn1.__pdf_

- Status 1

## Status 2

- Applied additional cuts used only by PNN2.
- TG-scattering cuts
*tgktim, tgenr, chi567, npitg, verrng, chi5max, angli, allkfit, epionk, ccdpul, timkf*
- Invert *targf* for 2-BM Rej. Sample
- Removes multiple charged particle decays
- Ke4, K2-scatter w/ Dalitz decay of
- Could escape front of target which could result in a B4 hit.
- Observed by Milind in e787.
- Not verified in e949
- Observe events in pawphoto (May 10th).
- Verify & Know values of cuts parameters (beam cuts May 15)
- What is more appropriate Bipul’s cut positions or PNN1?
- Need to go thru every cut and determine the appropriate cut position.
- Acceptance & Rejection of all beam cuts.
*epitg* is currently ETG fiber > 5MeV (PNN1 value).  Bipul’s > 3MeV.

## Summary

- N1bm measured and ‘good’.
- N2bm measured and not good yet.
- 1st draft numbers ready in 3 weeks (May 23).
- As cuts are modified and/or finalized, I can push the button to get updated values.
- What is next for me?
- Acceptance studies
- Help with target fitter