# Presentation: 140151

## A long-baseline experiment with the IHEP neutrino beam Y. Efremenko

**Presented by**

## Prospects to measure neutrino oscillation patternwith  very large area underground detectorat very long baselines

- V. Ammosov, V. Garkusha, A. Ivanilov, V. Kabachenko, E. Melnikov, F. Novoskoltsev, A. Soldatov, A. Zaitsev***IHEP, Protvino, Russia*****hep-ph/0205300**

## ConceptMeasurement of  disappearance with a very large baseline

**Concept****Measurement of ************ disappearance with a very large baseline**

-  **UNK tunnel -**** ****huge scintillator based muon counter (not calorimeter !)**
** ****Surrounding soil is a**** ****neutrino target**
** ****TOF and segmentation gives**** ****direction to the neutrino source**
** ****Location at 50 m underground gives good cosmic ray ****background suppression**
** ****Energy scan with Narrow Band neutrino beam to see**** ****oscillation pattern**

## Location

**~7600 km**

**~7000 km**

**~2000 km**

## Range for oscillation

**Range for oscillation**

**This set of L/E will let us to:**
**Observe the oscillation pattern**
**Give as precise measurement of ********m****2**** and mixing**
** ****Measure asymmetry in P(************) v.s. P(anti-************)  due to matter effect ******** ******** and ********13**** measurement**
**test CPT violation **

**For beam energy 1-15 GeV GSI, and JHF (or FNAL) are in right place to cover at least one full oscillation wave**

## Concept of neutrino beamNeeded energy resolution

**Concept of neutrino beam****Needed energy resolution**

**Blue line – mono energetic****	****Green line - ********E********/E********=15%****	**** ****Red line- ********E********/ E********=40% ****	**
** ********E********/ E********=15% (Narrow band beam) is adequate to see full oscillation wave**

## 2 graphite target
H1,H2 - 3 m parabolic horns ( 200 kA )
B1,B2 - 2 m dipoles with 400 mm gap
400 m  decay region ( 40 m target area)
 2 m decay pipe
Energy setting is tuned by  scaling dipole current and adjustment of  target location

**H1,H2 - 3 m parabolic horns ( 200 kA )**
**B1,B2 - 2 m dipoles with 400 mm gap**
**400 m  decay region ( 40 m target area)**
****** ****2 m decay pipe**
**Energy setting is tuned by  scaling dipole current and adjustment of  target location**

**Neutrino focusing system**

## Beam Simulations

**Proton energy 50 GeV**

**Beam Simulations**

**1.7, 3.5, 7.0, 10.5 and 14.0 GeV energy settings**
********** ****CC events -solid lines**
**anti-************ CC events - dashed lines**

**M**

## Concept of the Detector

**Concept of the Detector**

** ****Extruded polystyrene sc. plates (production in IHEP)**
** ****PMMA Kumarin-30 doped WL shifters**
** ****light collection from both ends via PMTs or APD**
** ****10 ph. el. per MIP**
** ****TDC and ADC for each readout channel**

**Not all parts of the tunnel is equally efficient. Some optimization is possible**

## Detector Acceptance (MC study)

**Detector Acceptance (MC study)**

**Conclusions:**
** ****background from NC as well as from ****ν****τ **** and ν****e ****is at a level of a few %**
**Ratio of an acceptances for neutrino and antineutrino does not depends of the energy**

**   ****Selection criteria:**** Two hits in different  scintillator  modules**
**	****            ****	****  ****Time difference between hits is greater than 10 ns (tunnel diameter 5 m.) **
**	****	****  ****Angle between neutrino and "track" directions is less than 30****0**
**	****	****  ****Only up going tracks**

## Expected Statistics

**Expected Statistics**

**Let consider How many POT we need to detect ****1000  ************  CC events (no oscillation) for the following beam settings**

**~10****21**** Protons on Target is enough !!!**

**Mixing**

**Realistic NB beam**

## Background

**Cosmic background < 50 events/year**
**Caveat: tunnel radioactivity have to be measured**

**If we can deliver 10****21**** POT during 10****7**** sec, with fact extraction,**
**Effective Detector life time could be ~ 1-10sec!**

## Expected Sensitivity

**1.5 10****-3 ****ev****2**** < ********m****2**** **** < 4.0 10****-3 ****ev****2**** **
**Expected accuracy in parameters measurements**
**For GSI:  ************m****2**** = 2.7********10****-5 ****ev****2 ****,  ********Sin****2****2******** = 0.01 **
**For JHF: ************m****2**** = 1.5********10****-5 ****ev****2 **** ,****  ******** ****Sin****2****2******** = 0.01**
**This is ~1% error  !!!**
**If we can do the same for antineutrinos say with 2% accuracy, then:**
**Test of CTP on the 3% level **
**by compare**** ********m****2**** ****for neutrinos with**** ********m****2 ****for antineutrinos**** **
**Sensitivity to matter effects on the 3% level**
**For ******** = P(************ ) -- P(anti-************ )**

**Expected Sensitivity**

## Terrestrial Matter Effects

**| ******** *****m*****32****2****| = 2.5****·****10**** -3**** eV****2**
******23**** = 40****o**
****** ****13**** = 13****o**** (*****s*****13****2**** = 0.05)**

******* ******m*****21****2**** = 1.4****·****10 ****-4**** eV****2**
****** ****12**** = 35****o**

**Calculations correspond to:**

**Conclusions:**** **
**Beam spread************E/E = 0.15 is sufficient.**
**There are “significant” terrestrial effects**
**For 7000 km baseline matter effects become dramatic!**

**GSI**

**JHF**

**vacuum,** no smearing

**Vacuum, **smearing
*******E*****/*****E***** = 0.15**

**matter **********

**matter anti- **********

## TME: asymmetry ACPT

**Black:     *********m*****32****2**** > 0**
**Blue:       *********m*****32****2**** < 0**
**Solid:       ******** = 0****o**
**Dashed:   ******** = 180****o**

**GSI**

**JHF**

**Conclusions:**** **
**determination of the ****sign of *********m*****32****2***** *****by the sign of asymmetry *****A******CPT *****is possible**
**Some information of the CP phase could be obtained as well**

## Conclusion

**•   ****Observation of oscillation patterns for ************ ****and ****anti-************ disappearance in the range ****0.5****·****10****-3**** < *********m*****2**** < 6.0****·****10****-3**** eV****2**
**Measurement of *********m*****2**** and *****I************ ****** *****with accuracy of****  ~ 1%**
**Search for ****genuine**** *****CPT***** violation**** in neutrino sector  with accuracy of**** ~ 3%**** for the ********=*********m*****2 ****(************)- *********m*****2****(anti-************ ****)**
**Observation of the matter effects**
**Unambiguous determination of the ****sign of *********m*****32****2***** *****by the sign of asymmetry *****A******CPT***

**For the very long baseline, narrow band beam, coarse Mt size detector, and ~10****21**** POT it is possible to:**

## Phase vs. Theta13

**TME: ************vs.  *****s*****13****2****  measurement:**
- at  ***E***** = 1 GeV** in dependence on **** and    ***s*****13****2**
-  for *******m*****21****2**** = 1.4****·****10 ****-4**** ** and  **2.7****· ****10 ****-4**** eV****2**** eV****2**
- One point corresponds to ***s*****13****2 ****= 0** (black circle)
- and five points with ******= 0****o****, 45****o****, 90****o****, 135****o**   and
**180****o**** **(marked by the same symbols) are
- plotted for the values of   ***s*****13****2 ****= ****0.01** (boxes),
**0.03** (circles) and **0.05** (diamonds).
- Straight line grid presents  ***A******CPT***** = 0**  (blue
- line),  ******0.04,********0.08,  ...**  (brown lines).
- Errors are for point  (***s*****13****2 ****= 0.03, ********= 45****o**) and
- correspond to statistics of  **10****3** events in the
- absence of oscillations.
**Conclusion:  ******** and *****s*****13****2**** can be measured with the use of *****A******CPT   *****(terrestrial effect)**