# Presentation: 415844

## Analysis Techniques & Status of the DONUT experiment

- Niki Saoulidou, Fermilab

- N. Saoulidou, Fermilab

## -Outline- 

**Introduction**
- Physics Motivation
**DONUT Experiment (Brief Review)**
**Spectrometer Analysis**
- Neutrino Event Selection (**A**rtificial **N**eural **N**etworks)
- Neutrino event Characterization (ANN)
**Emulsion Analysis**
- Neutrino Event Location
- Decay Search
- Signal from Background Separation (ANN)
**Conclusions**

- N. Saoulidou, Fermilab

## -Direct Observation of the vτ-

- Weak Isospin Lepton Doublets:
- The vτ  was not directly observed, the way the other two neutrinos have, through its CC interactions although there was plenty of indirect evidence that the tau lepton has a neutral, spin 1/2 weak isospin partner.
- E872 Experiment :  **D**irect **O**bservation of the **NUT**au  :

- N. Saoulidou, Fermilab

## -The  DONUT Collaboration -

*Aichi Univ. Of Education *
-                  K. Kodama, N. Ushida
*              **Athens University*
- C. Andreopoulos,  N. Saoulidou. G. Tzanakos
-        *California/Davis University*
-                           P. Yager
-                      *Fermilab *
-       B. Baller, D. Boehnlein, W. Freeman,
-       B. Lundberg, J. Morfin, R. Rameika
-            *Gyeongsang University*
-       J. S. Song, I. G. Park, S. H. Chung
-           *Kansas State University*
-      P. Berghaus, M. Kubanstev, N. W. Reay,
-        R. Sidwell, N. Stanton, S. Yoshida

-                          *Kobe University*
-                               S. Aoki, T. Hara
-                         *Kon-kuk University*
-                                        J.T. Rhee
-                          *Minnesota  University**** ***
-              D. Ciampa, C. Erickson, K. Heller, R. Rusack
-         R. Schwienhorst, J. Sielaff, J. Trammell, J. Wilcox
-                            *Nagoya University  *
- N. Hashizume, K. Hoshino, H. Iinuma, K. Ito, M. Kobayashi,
-    M. Miyanishi, M. Komatsu,  M. Nakamura, K. Nakajima,
-     T. Nakano, K.Niwa, N. Nonaka, K. Okada, T. Yamamori
-  *Pittsburgh University*
- T. Akdogan, V. Paolone
*Tufts University*
-                T. Kafka, W. Oliver, J. Schneps, T. Patzak

- N. Saoulidou, Fermilab

## -How the experiment is done -

**-How the experiment is done ****-**

**KINK**

- N. Saoulidou, Fermilab

## -Analysis Flow- 

**Calibrate plates**

**Vertex prediction from FT**

**Scan ****5x5x15mm****3**** ****volume**

**Vertex found from digital info**

**Scan again ****2.5x2.5x10mm****3**** ****for decay search**

**Look for kinks & tridents in 1****ry**** tracks**

**Special scans (momentum, electron ID)**

**Analysis  for ****τ****, charm**

***τ****** *****Sample**

***charm**** ***Sample**

**Reconstruct raw data**

**Software filter for “interesting events” **

**ANN & visual scanning    for “neutrino interactions”**

**Event Characterization with Spectrometer info.**

**4.0 x 10****6**

**4.0 x 10****4**

** ****1000**

- N. Saoulidou, Fermilab

## -Goals of the ANN analysis involving spectrometer information – 

** ****Use Artificial Neural Network techniques**** to identify and classify**** Neutrino Interactions into: **
** ****CC  ****ν****μ****   ****ν****e****   ****ν****τ**** **
** ****NC**
** ****Requirement****: MC should be capable of describing very well the neutrino data.**

- N. Saoulidou, Fermilab

## -Output of ANN2 (NC - ve CC )-

**-Output of ANN2 (NC - v****e**** CC )-**

**NC**

**v****e**** CC**

**cut **

- This network shows a quite good behavior and by choosing a **cut @ 0.5** we select  **signal (NC ) **and at the same time **background **events** (v****e**** CC)**  with :
-                               **NC           efficiency**** ****68 % -****  ****purity **** ****80 %**** **
**              ****v****e**** **** CC          efficiency ****86 % -****  ****purity****  76 % **

- N. Saoulidou, Fermilab

## -Expected number of neutrino interactions per  run period & per emulsion module- 

**Expected number        964 ± 235 **
**Observed number           909**
**Difference             55 ± 235**** **

**Ratios (%)             ****ν****μ**** ****CC         ****ν****e**** ****CC****	****     ****ν****τ**** ****CC          NC**
** ****expected     ****	**** 32.3±2.4     36.3±3.9        ------       31.4±2.0**** **
** ****observed     ****	**** 34.3±1.6     36.0±1.6        ------        29.7±1.5**** **
**Difference         2.0 ±2.9      0.3 ±4.0                         1.7 ±2.5**
**Numbers****	****    ****	****  ****ν****μ**** ****CC           ****ν****e**** ****CC****	****      ****ν****τ**** ****CC          NC**
** ****expected    ****	****312 ± 92      350 ±79        ------        303 ± 75**
** ****observed     ****	****312 ± 15      327 ±15         ------        270 ± 15**
**Difference            0 ± 93       23 ± 80                          33 ± 76**** **

**Good agreement (within ~ 1 ****σ****)**

- N. Saoulidou, Fermilab

## -Decay Search- 

**1.  Long Decays**
** ****parent measured**
** ****kink resolved**
** ****τ**** ******** no 1****ry *****lepton***
** ****~75%**

**2.  ****Short Decays**
** ****IP wrt 1****ry**** vertex**
** ****only daughter meas. **
** ****daughter seen in spect.**
** ****~25%**

- N. Saoulidou, Fermilab

## - Signal & Background -

**Charm background**
**Interactions (scattering)**
**Tau ***** *****signal **

***D*****+**

**Lepton missed**

- N. Saoulidou, Fermilab

## -ANN vτ CC - hadron scattering results on the 37 recognized kinks- 

**-ANN v****τ**** ****CC - hadron scattering results ****on the 37 recognized kinks-**** **

_**EVENTS THAT EXCEED THE 0.5 CUT IN THE ANN OUTPUT FUNCTION**_
_**RUN  EVENT  P**__**d**__**      **__**θ**__**d**__**            **__**P**__**T**__**      L**__**d**__**        **__**θ**__**p**__**     **__**Δφ   **__**Probabilities**_
**3263 25102  1.900  0.1300  0.247 1890.1  0.1772  0.176   0.136*****
**3024 30175  2.900  0.0936  0.271 4504.8  0.0279  1.027   ****0.971   **
**3039  1910  4.600   0.0895  0.412  276.5  0.0653  2.684   ****1.000**
**3333 17665 21.400  0.0130  0.278  564.6  0.0154  2.806   ****1.000**

**Data**

** ****MC**

**Δ****p/p=30%**

- N. Saoulidou, Fermilab

## -DONUT Status- 

**-DONUT Status-**

-                                     **PHASE 1     ****PRESENT**
- Neutrino Interactions      **698  (898)  **     **909  (1026)**
- Emulsion Digitized Info     **499 **                **650**
- Located                                   **262**                 **432**
- Decay Search                             **203**                 **432**
- Tau Events                              **         4 **                   **6* **** **

- N. Saoulidou, Fermilab

##  (ντ CC 1-prong observed     : Ns= 4.00 Bkg= 0.34 PT cut)  

**ν****τ**** ****CC 1-prong observed  :  N****s****=3.00 ** ***individual event probabilities***
-  (ντ CC 1-prong observed     : **N****s****=** 4.00 **Bkg=** 0.34 ***P******T****** cut) ***
- 		                                                   **K. Kodama et al., Phys.Lett.B504:218-224,2001**
**	****	****	****	****      ****R. Schwienhorst et al., Phys.Lett.B513:23-29,2001 **
***Poisson Probability of the Background fluctuating to the Signal Level :***
*** ******2.6 x 10******-8****** ******( 4 x 10******-4 ******)***
*** ***ντ CC 1-prong expected   :  5.3 ± 1.6
**ν****τ**** ****CC**** ****candidates observed :  6**
-  ντ CC  expected   	       : 6.3 ±1.8
**Total Charm events observed : 8   **
- Charm events expected             : 6.9 ±1.8
**Charged Charm events observed : 4 ***** ***
- Charged Charm events expected    : 3.0 ±1.2
**Charged Charm 1-prong events observed : 3  **
- Charged Charm 1-prong events expected      : 1.3 ±0.5

**-Tau neutrino CC and Charm interactions- backup**

- N. Saoulidou, Fermilab

## Slide 15

- N. Saoulidou, Fermilab

## -Conclusions-

** **
**ANN techniques have been successfully used in**
**     ****the following parts of the analysis:**
**  ****- Neutrino event selection**
**  ****- Neutrino event characterization**
**  ****- Signal selection and Background estimation**
**The ANN analysis is consistent with expectations.**
**The second Phase of the analysis  is continued and expected to finish soon.**

- N. Saoulidou, Fermilab

## Slide 17

## -Example of a neutrino event- ?

**-Example of a neutrino event- ?**

- N. Saoulidou, Fermilab

## - Characteristics of Selected ANN events- backup 

**- Characteristics of Selected ANN events- backup**** **

**P****T**** of experimental kinks**** **

**P****T**** of MC kinks for hadron scattering events (red) and tau decays (black)**

- N. Saoulidou, Fermilab

## - Characteristics of Selected ANN events cont.- backup

**MC, Hadron scattering: Black  ****MC, Tau decays: Yellow ****Data, Selected candidates : Red**

**Decay Length**

**Daughter momentum**

**Daughter P****T**

**Parent angle**

**Daughter angle**

**Δ****φ**

- N. Saoulidou, Fermilab