# Presentation: 937178

## Quasi-Elastic Neutrino Scattering measured with MINERvA

- Ronald Ransome

- Rutgers, The State University of New Jersey

- Piscataway, NJ

- Rutgers Seminar Oct. 13

## The MINERvA Collaboration

*D. Drakoulakos, P. Stamoulis, G. Tzanakos, M. Zois**University of Athens, Athens, Greece*
*C. Castromonte, H. da Motta, M. Vaz, J.L. Palomino **Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro, Brazil*
*D. Casper, C. Simon, J. Tatar, B. Ziemer**University of California, Irvine, California *
*E. Paschos**University of Dortmund, Dortmund, Germany*
*M. Andrews, B. Baldin, D. Boehnlein, C. Gingu, N. Grossman, D. A. Harris#, J. Kilmer, M. Kostin, J.G. Morfin*, J. Olsen, A. Pla-Dalmau, P. Rubinov, P. Shanahan **Fermi National Accelerator Laboratory, Batavia, Illinois*
*J. Felix, G. Moreno, M. Reyes, G. Zavala**Universidad de Guanajuato -- Instituto de Fisica, Guanajuato, Mexico*
*I. Albayrak, M.E. Christy, C.E. Keppel, V. Tvaskis**Hampton University, Hampton, Virginia*
*A. Butkevich, S. Kulagin**Institute for Nuclear Research, Moscow, Russia*
*I. Niculescu. G. Niculescu**James Madison University, Harrisonburg, Virginia*
*W.K. Brooks, A. Bruell, R. Ent, D. Gaskell, D. Meekins, W. Melnitchouk, S. Wood**Jefferson Lab, Newport News, Virginia*
*E. Maher**Massachusetts College of Liberal Arts, **North Adams, Massachusetts*

- R. Gran, C. Rude*University of Minnesota-Duluth, Duluth, Minnesota*
- A. Jeffers, D. Buchholz, B. Gobbi, A. Loveridge, J. Hobbs, V. Kuznetsov, L. Patrick, H. Schellman*Northwestern University, Evanston, Illinois*
- L. Aliaga, J.L. Bazo, A. Gago*Pontificia Universidad Catolica del Peru, Lima, Peru*
- S. Boyd, S. Dytman, I. Danko, D. Naples, V. Paolone*University of Pittsburgh, Pittsburgh, Pennsylvania*
- S. Avvakumov, A. Bodek, R. Bradford, H. Budd, J. Chvojka, M. Day, R. Flight, H. Lee, S. Manly, K. McFarland*, A. McGowan, A. Mislevic, J. Park, G. Perdue*University of Rochester, Rochester, New York*
- R. Gilman, G. Kumbartzki, R. Ransome#, E. Schulte*Rutgers University, New Brunswick, New Jersey*
- S. Kopp, L. Loiacono, M. Proga*University of Texas, Austin, Texas*
- H. Gallagher, T. Kafka, W.A. Mann, W. Oliver*Tufts University, Medford, Massachusetts*
- R. Ochoa, O. Pereyra, J. Solana*Universidad Nacional de Ingenieria, Lima, Peru*
- D.B. Beringer, M.A. Kordosky, A.G. Leister, J.K. Nelson*The College of William and Mary, Williamsburg, Virginia*
- * Co-Spokespersons# Members of the MINERvA Executive Committee

-  A collaboration of ~80 Particle, Nuclear, and Theoretical physicists from 23 Institutions

- Rutgers Seminar Oct. 13

**Notes:**
particle + nuclear physics

## MINERvA Experiment

**M**ain **IN**jector **E**xpe**R**iment **ν-A **(at Fermi-Lab)
- Placed upstream of MINOS near-detector in NuMI beam line
- Fully active detector designed to make high precision measurements of neutrino-nucleus interactions
- Built around central tracking volume of fine-grained scintillator
- Measure cross-sections
- Full event reconstruction
- Liquid 4He, C, Fe, and Pb nuclear targets

## NuMI Neutrino Flux

- Intense neutrino beam with broad energy range
- MINERvA will use mixture of LE, ME, HE beam

- Rutgers Seminar Oct. 13

## Neutrino-Nucleon Cross section

- NuMI flux range

- 1-20 GeV

- Rutgers Seminar Oct. 13

## Event Rates 13 Million total CC events in a 4 year run

- Assume 16**.0x**1020** in LE********ME, and HE configurations in 4 years**

**Fiducial Volume = 3 tons CH, ≈  0.6 t C, ≈ .6 t Fe  and ≈ .6 t Pb**
**Expected CC event samples:**
**8.6 M ******** events in CH**
**1.4 M ******** events in C**
**1.4 M ******** events in Fe**
** ****1.4 M ********events in Pb**

**Main CC Physics Topics with Expected Produced ******** ****Statistics in 3 tons of CH**
**Quasi-elastic**** ****	****	****	****	****0.8 M events **
**Resonance Production**** ****	****	****	****1.6 M total**
**Transition: Resonance to DIS****	****	****2 M events**
**DIS and Structure Functions**** ****	****	****4.1 M DIS events**
**Coherent Pion Production****	********85 K CC / 37 K NC**
**Strange and Charm Particle Production**** ****	****> 230 K fully**** ****reconstructed events**
**Generalized Parton Distributions**** ****	****	****order 10 K events****	**
**Nuclear Effects**** ****	****	****	****C:1.4 M, Fe: 1.4 M and Pb: 1.4 M**

- Rutgers Seminar Oct. 13

## Detector Design

**Fully Active ****Target: 8.3 tons**

**Nuclear Targets:**
**6.2 tons (40% scint.)**

**SideECAL**

**Fully Active Target**

**Downstream ECAL**

**Downstream****HCAL**

**Nuclear****Targets**

**Side HCAL (OD)**

**Veto Wall**

- Thin modules hang like file folders on a stand
- Attached together to form completed detector
- Different absorbers for different detector regions

- 108 Frames in total

- Rutgers Seminar Oct. 13

**Notes:**
consequent masses (QUICK)

## Active Scintillator Target

- Triangular scintillators are arranged into planes – Wave length shifting fiber is read out by Multi-Anode PMT

- Particle trajectory

- WLS fiber

- 2.5 mm resolution with charge sharing
- Light yield 6.5 photo-electron/MeV

- 1.7 cm

- 3.3 cm

- PMT

- WLS

- Scintillator

- Clear Fiber

- Rutgers Seminar Oct. 13

## Nuclear Target region

**Carbon**, **Iron**, **Lead – ****mixed elements in layers to give same systematics**

- XUXVXUXV (4 tracking points) between each layer

- Main detector

- Beam

- Rutgers Seminar Oct. 13

## Quasi-Elastic Neutrino Interactions (QE) 

- Charged current:

- n p

- cc~ c1GE2 + c2GM2 + c3FA2

- GE2 , GM2 extracted from electron-proton elastic scattering
-  **F****A****2 ****is the axial form factor** (extracted from neutrino-neutron scattering cross section)
- c1, c2, c3  kinematic factors
- c3FA2 accounts for about half of cross section

## Experimental Challenges

- No free neutron targets, _must use nuclei_!
- Need to isolate QE events from other processes
- Use of nuclei introduces complications:
- Non-zero total transverse momentum
- Fermi momentum
- Final state interactions (FSI)
- FSI:
- Particle production
- Proton Loss
- Non-QE processes can mimic QE
- Possible modification of form factor
- Projected to be a few percent (theoretical)
- Thick targets cause:
-  Particle absorption

## Quasi-elastic scattering

- Signature is p with no other final state particles and zero transverse momentum
- If reaction occurs in nucleus –
- Fermi momentum gives non-zero transverse momentum
- FSI can give additional particles
- Resonance and DIS can produce proton + unobserved neutrons, mimicking QE
- QE ranges from 30% of total cross section for 2 GeV neutrinos to less than 5% of total cross section for 10 GeV neutrinos
- Requires good background rejection

- Rutgers Seminar Oct. 13

## Quasi-elastic

- Question – what is the nuclear dependence of extracted form factor due to contamination and losses, i.e. experimental effects?
- Question – what is the effect due to nucleon being in nuclear medium, i.e. intrinsic modification?

- Rutgers Seminar Oct. 13

## Anticipated statistics on Axial FF 

- 800 K QE on C
- 150 K QE on Fe and Pb
- Comparisons in low Q2 better than 1% statistical uncertainty

- Rutgers Seminar Oct. 13

## Simulation

- Use GENIE:
- Neutrino event generator
- Uses combination of theoretical models and world neutrino data to generate events
- Generates events on multiple nuclei
- For this simulation – use fixed neutrino energies
- http://howto.genie-mc.org/
- Model Detector
- Check for track overlap (reduces observed multiplicity)
- Particles stopped in interaction target
- Count observed tracks
- For this simulation – assume perfect particle ID

## Analysis

- Analysis Cuts:
- Number of tracks
-  p – ideal case for QE event, or single muon
- Also looked at higher multiplicities – improves efficiency, decreases purity
- Particle ID: *Non-QE processes produce pions*
- Vetoed charged and neutral pions
- Q2 (GeV/c)2
- 0-1.2 (GeV/c)2 bins of 0.3 (GeV/c)2
- 1.2 (GeV/c)2 and greater
- Total Transverse Momentum
- Less than 0.25 GeV/c cut
- No Transverse Momentum cut for this simulation
- Event type (supplied by event generator)
**Efficiency **= QE with cuts/Total QE
**Purity** = QE with cuts/(all processes with cuts)

## or p events

- Rutgers Seminar Oct. 13

## Results

- Efficiency is high in low Q2 region (80-100%)
- Nearly identical for C and Pb
- Little energy dependence
- Purity – decreases with Q2 and neutrino energy
- Remains above 70%, even for 10 GeV neutrino
- C and Pb have similar Q2 dependence, with Pb 5-10% less than C

- Rutgers Seminar Oct. 13

## Conclusions

- Corrections for C and Pb are not dramatically different
- Relatively small energy dependence
- Magnitude of correction 30% or less
- Will need to compare actual data with GENIE output to determine accuracy of GENIE
- Expect that we can compare extracted cross sections to better than 5% systematics
- Comparison to He still underway

- Rutgers Seminar Oct. 13