# Presentation: 708756

##  Event LocationN. Saoulidou and G. TzanakosUniversity of Athens, Department of Physics,Div. Of Nuclear & Particle Physics
15771 Athens , Greece

**15771 Athens , Greece**

**DONUT Collaboration meeting**
**Pittsburgh PA 26-10-2001**

- N. Saoulidou & G. Tzanakos

## OUTLINE

**Event location**
**New slightly different approach **
**Attempted events **
**Results - Status**** **
**Conclusion - Ongoing work**

- N. Saoulidou & G. Tzanakos

## Event Location : Goal - Method

- Our goal is to be able to successfully **locate neutrino interactions** in order to :
**Locate the  period 3 new events.**
**Contribute to overall event location.**
- The **method** we have investigated and modified in certain points is **Bruce’s **code for event location.
- We have used **38 located events** with **existent location m-files** (unfortunately no more location m-files of located events exist) to **check our performance.**

- N. Saoulidou & G. Tzanakos

## Event Location : Logic

-  **Set track selection criteria :**
- Starting Tracks
- Tracks with 2 or more segments
**Tracks with good ****χ****2**** ( < 6 ) **
**Set two-track vertex selection criteria:**
- Vertex IP  < 5 μm
**At least one long vertex track (     3 segments)**
- Vertex no more than 2 plates upstream of the vertex track plates
**At least one emulsion track match with a spectrometer track**
**Add more tracks to the vertex that have IP < 10 ****μ****m:**
**Check if vertex tracks connect upstream.**
**Match emulsion vertex tracks to spectrometer tracks and visually scan candidate vertices to select  the best.**

**Change **

- N. Saoulidou & G. Tzanakos

## Event Location : Changes

- The result of the changes in the logic is that :
**Greater number** of  **two - track vertices** are formed in the first step.
- More **emphasis **is given on the **matching** of **emulsion tracks** with **spectrometer tracks** which finally reduces the number of formed vertices but keeps those **more related** to the **actual event**.

- N. Saoulidou & G. Tzanakos

## Results on 38 Located Events 

**EVENTS                                                             38**
**LOCATED (OUR VERSION)                          33**
** ****NOT  LOCATED (OUR VERSION)                 5**
** ****LOCATED (BRUCE’S CODE)                        28**
** ****NOT  LOCATED (BRUCE’S CODE)              10**
- The reasons for not locating the 5 events are :
- 2 events had **large IP** of tracks from vertex ~ > 10-15 microns
-      (Bruce’s code could not locate them either)
- 2 events had **primary tracks** with very **large ****χ****2**
-              (Bruce’s code located them)
- In 1 event  located by Carolyn we **could not find** one of the 2 **primary tracks** in the **daft file** (Bruce’s code did not locate it either)

- N. Saoulidou & G. Tzanakos

## Event  3040_13590

**Event  3040_13590**

- >>>>>>>>>>>>>>>>> Reconstructed Vertices in 3040_13590 <<<<<<<<<<<<<<<<<<<
- ivx=  1   vtx=    58620.55    16498.50   598162.56 chi=    0.12
- Errors                0.60        0.60        1.52 micron
-  -------------------------------------------------------------------------
-                                               IP     vtx   spect      trk         trk        dthet     dthet         thet        thet
-  _____trk______nseg__micron__chi___nht___chis___mom____U______V______U______V
-   3-241-0009703  8            0.28    0.17     13        5.2        4.6        -0.004  -0.004 -0.021  0.115
-   4-241-0009017  2            0.95    2.06      0         0.0        0.0         0.000   0.000  0.295  0.082
-  -------------------------------------------------------------------------

**Trk 1  u slope  v slope   **
**          ****- 0.024  0.110 **
**  ****exist in m-file (matched)**
**Trk 2  u slope  v slope  **
**         ****-0.248  0.539 **
**    ****does not exist in m-file**

- N. Saoulidou & G. Tzanakos

## Event  2879_12293

**Event  2879_12293**

- >>>>>>>>>>>>>>>>> Reconstructed Vertices in 2879_12293 <<<<<<<<<<<<<<<<<<<
- ivx=  1   vtx=  -174028.91  -104231.44   614721.31 chi=    0.14
- Errors                0.60        0.60        1.52 micron
-  -------------------------------------------------------------------------
-                                              IP     vtx   spect       trk        trk       dthet       dthet       thet         thet
- _____trk______nseg__micron__chi___nht___chis___mom____U______V______U______V
-   1-121-0035440  8             0.30   0.20    26       2.9       46.5      -0.004      0.001    0.007     -0.040
-   2-121-0036022 14            1.35   4.18    13       3.3         0.0       0.000     -0.001   -0.214      0.171
-   3-121-0036499  3             0.83   1.39    17       1.7         0.0      -0.001     -0.005   -0.118     0.362

**Already located !**

- N. Saoulidou & G. Tzanakos

## Event  2881_06913

**Event  2881_06913**

-             >>>>>>>>>>>>>>>>> Reconstructed Vertices in 2881_06913 <<<<<<<<<<<<<<<<<<<
- ivx=  1   vtx=  -183913.48  -195943.50    41269.38 chi=    0.00
- Errors                0.60        0.60        1.52 micron
-  -------------------------------------------------------------------------
-                                               IP     vtx    spect      trk        trk       dthet       dthet        thet        thet
-  _____trk______nseg__micron__chi___nht___chis___mom____U______V______U______V
-   2- 71-0030960  6         3.36        8.05    17       1.8        0.0      -0.014      0.006        0.103  0.058
-   3- 71-0030975  6         1.72        2.20    20       2.7        0.0      -0.009      0.003       -0.037  0.072
-   4- 71-0031400  5         3.93      10.10    16       4.0        0.0       0.006       0.007        0.209  0.205
-  -------------------------------------------------------------------------

- N. Saoulidou & G. Tzanakos

## Event  2884_14149

**Event  2884_14149**

**Incomplete Daft file <=> Emulsion tracks connect upstream (Carolyn) ... **

- ivx=  1   vtx=   112680.38    63582.50   570966.75 chi=    0.01
- Errors                0.60        0.60        1.52 micron
-  -------------------------------------------------------------------------
-                                              IP     vtx    spect     trk        trk          dthet     dthet       thet         thet
-  _____trk______nseg__micron__chi___nht___chis___mom____U______V______U______V
-   1-441-0022686 11   0.08   0.01   20    4.9     5.0 -0.001 -0.011  0.036 -0.005
-   2-441-0022887 12   0.09   0.01   12    3.2     0.0  0.004  0.008 -0.012  0.055
-  -------------------------------------------------------------------------

- N. Saoulidou & G. Tzanakos

## Event  2913_05064

**Event  2913_05064**

- >>>>>>>>>>>>>>>>> Reconstructed Vertices in 2913_05064 <<<<<<<<<<<<<<<<<<<
- ivx=  1   vtx=   -75485.93      738.37   570843.88 chi=    0.00
- Errors                0.60        0.60        1.52 micron
-  -------------------------------------------------------------------------
-                                             IP     vtx      spect     trk       trk        dthet       dthet        thet      thet
- _____trk______nseg__micron__chi___nht___chis___mom____U______V______U_____V
-   3-441-0008709 14         0.23     0.09    15       7.4         0.0      -0.009      0.000    -0.048 -0.056
-   4-441-0008602 13         1.03     1.52      0       0.0         0.0        0.000     0.000     0.007 -0.084
-   5-441-0008729 14         1.11     2.01      0       0.0         0.0        0.000     0.000     0.120 -0.053
-  -------------------------------------------------------------------------

- N. Saoulidou & G. Tzanakos

## Event  3073_18731

**Event  3073_18731**

- >>>>>>>>>>>>>>>>> Reconstructed Vertices in 3073_18731 <<<<<<<<<<<<<<<<<<<
- ivx=  1   vtx=  -146124.30    32467.28    10818.54 chi=    0.00
- Errors                         0.60            0.60             1.52 micron
-  -------------------------------------------------------------------------
-                                             IP     vtx     spect      trk        trk       dthet      dthet       thet       thet
- _____trk______nseg__micron__chi___nht___chis___mom____U______V______U____V
-   1-301-0017295  6         1.16     2.20      21       4.7      183.1     0.004      0.002    0.002  0.020
-   2-291-0015743  2         1.56     3.06        8       1.7          0.0    -0.003     -0.005  -0.071 -0.065
-   3-301-0017067  6         1.19     3.20        8       2.0          0.0     0.005     -0.009    0.012 -0.172
-  -------------------------------------------------------------------------

- N. Saoulidou & G. Tzanakos

## Event Location : Ongoing work

- Using this method we are **attempting event location** of not-located events.
- We are also using our procedure for obtaining vertex predictions to **examine** whether the **scan volume** for these events is the correct one.
- We are working on **ideas **(**as we gain experience**) on **possible improvements** on the **event location procedure.**

- N. Saoulidou & G. Tzanakos

## Conclusions

- We have **became familiar** and **slightly modified** **Bruce’s code** for **event location.**
- We have **tested ** our **performance** on **38** already **located** events with **satisfactory results**.
- We are now **attempting  location** of  **not-located events.**

- N. Saoulidou & G. Tzanakos