# Presentation: 007085

## Neutrino Possibilities at the SNS

## Motivation

**For me as an experimentalist motivation is two fold**

**On this workshop we have nice theory talks about motivation**

**New exciting, unexplored opportunities !!!**

## Neutrino Spectra

**Neutrinos from SNS are in the same energy range as neutrinos from Supernovae !**

**Supernovae**

**SNS**

********

********

******e**

**Normalized spectra**
**N(********e****) = ( 12 / W****4****) E****2********  ****( W - E******** ****)**
**N(************) = ( 6 / W****4****) E****2******** **** ( W - 2 / 3 E******** ****)**
**W=52.83 MeV**
********** ****is monoenergetic at ~ 30 MeV**

## SNS layout

**1.3 GeV proton linear accelerator**

**Accumulator ring**

**2 MW Mercury target**

## SNS Parameters

**Primary proton beam energy - 1.3 GeV**
**Intensity - 9.6 ******** 10****15**** protons/sec**
**Pulse duration - 380ns(FWHM)**
**Repetition rate - 60Hz**
**Total power – 1.4 MW**
**Liquid Mercury target**
**Number of neutrinos produced ~ 1.9********10****22****/year**

## Present status

**Present status**

## Target building

**Proton Beam**

## Mercury target

**Mercury Inventory – 20 t**
**Flow rate 340 kg/sec**
**V****max**** 3.5 m/sec**
**T****in**** 60****0****C**
**T****out**** 90****0****C**

**Mercury lasts the entire 40 year lifetime of SNS with no change out required**
**Stainless steel vessel should be replaced a few times per year**

## Neutrino Production

**Neutrino Production**

## Comparison of SNS with others stop pion facilities

| Facility | LANSCE | ISIS | SNS |  SNS Advantage |
| --- | --- | --- | --- | --- |
| Beam energy | 0.8 GeV | 0.8 GeV | 1.3 GeV | 1.7 |
| Beam current | 1.0 mA | 0.2 mA | 1.1 mA |  |
| Coulomb delivered per year to the target | 6500
(LSND) | 2370
(KARMEN) | 22000 | 103.5 |
| Beam structure | Continues | Two 200 nsec bunches separated by 300 nsec repetition rate - 50 Hz  | 380 nsec FWHM
pulses at 60 Hz | Separation 
 from e, better BG suppression |
| Target | Various | Water cooled Tantalum | Mercury
 | Source compactness |

## Some Details of Interaction in the Target

**Average interaction energy is ~1.1 GeV**

**Average interaction depth ~11 cm**

- Proton interacts at the front part of the target

## DIF vs. DAR

**200 MeV/c pions range in mercury is ~ 5 cm**
**Very few pions have a chance to decay before coming to the rest**

**Pion Spectra**

**Because of the bulk Mercury target, SNS is a Decay At Rest facility !!**

## Actual spectra of neutrinos from SNS

**Energy****	****             ****	****	****Time**

## Neutrino Rates

**Number of protons on the target for 1.1 mA is 0.687****·****10****16 ****sec****-1**
**Number of each flavor  neutrino produced by one proton  is 0.13**
**Lets assume SNS live time is 2/3 of the year**
**Number of each flavor of neutrinos produced at SNS is 1.9****·****10****22 ****year****-1**
*Caveat:*
*There is larger flux of antineutrinos from decay of radioactivity in the target*
*However: their energy is a few MeV*

## Cross Sections

**Reaction**
******e****e****-**** ******** ********e****e****-**
**********e****-**** ******** ************e****-****	**
******e****12****C ******** ****12****N****gs**** e****-**
******e****12****C ******** ********e ****12****C*******
**********12****C ******** ************12****C*******
******e****56****Fe ******** ****56****Co e****-****	**

- Integrated Cross Section
**0.297********10****-43**** cm****2**
**0.050********10****-43**** cm****2**
**0.92********10****-41**** cm****2**
**0.45********10****-41**** cm****2**
**0.27********10****-41**** cm****2**
**~2.5********10****-40**** cm****2**

**SNS will deliver ~ 1.9****·****10****22**** neutrinos per year**

## Necessary detector mass

**One should take into account: efficiency and fiducial mass**

**Efficiency ~ 30 %**

**Time measurement ~ 1 Year, statistics 1000 events**

## Possible detector location

**Possible detector location**

## Limiting Factors

**Time to build – it looks like any time is feasible. SNS at full power - 2008**
**Distance from the target – 18.3 ******** 22 m**
**Available foot print ~ 4****·****6 m****2**** **
**Available head room – 6-7 m**
**Detectors and Shielding mass – Floor loading limitations**
**BG from SNS – Initially looks OK. Need more study**

## Targets

- 2d, 12C, 16O, 127I, ** **51V, 27Al, 9Be, 11B, 52Cr, 56Fe, 59Co, 209Bi, 181Ta

** ****One objective of this workshop is to establish a shopping list of targets**
**In addition we need:**
** ****to set priorities for target studies**
**to know how accurately we have to measure cross sections**

**Is following list is good enough to start with?**

## Two detector concept

**To have maximum flexibility to measure variety of various isotopes we suggest a  two detector concept **

**Homogeneous – for targets that can be made in liquid (transparent) form**

**Heterogeneous – for all other targets**

## Homogeneous detector

**Liquid targets**
- 2d, 12C, 16O, 127I

**Hermetic vessel with capability of good photon collection**

- ~ 15 t fiducial mass

**3 m**

**Scintillation / Cherenkov detector**

## Questions for the Homogeneous detector

- Shape  - rectangular vs. Spherical
- Photon detectors – PMT vs. PD or APD
- Necessary energy and space resolution
- Photon detector coverage?
- Directionality
- Number of electronic channels
- Requirements for electronics and DAQ
- PID capability
- Purification system
- Cost

## Heterogeneous detector

**Designed to handle metals or other solid targets**
- 51V, 27Al, 9Be, 11B, 52Cr, 56Fe, 59Co, 209Bi, 181Ta

**Requirements:**
**Targets should be easily replaceable**
**Mass of the sensitive part of the detector should be less than target mass**
**Modular structure**

## Heterogeneous detector II

**Active detector – straw gas tubes**
**Energy measurement - by range**

**e**

**Expected energy resolution for tubes 10mm and 0.5 mm at 30 MeV is ~ 25%**
**Detector size for 20 t fiducial mass is – 3.0 ******** 2.3 ******** 2.3 m****3**
**Number of channels ~50000**

## Questions for the Heterogeneous detector

- Is it the right technology
- Is energy resolution is good enough
- How easy/fast is it to replace targets
- Can we achieve good 3 dimensional resolution
- PID
- Number of electronic channels
- Requirements for electronics
- How complicated is a gas system ?
- Cost

## Proposed enclosure

- S

**Detector 1**

**Detector 2**

- Shielding

**Veto**

## Detectors + Shielding Mass

**Footprint under enclosure can support only 138 t.**

**For the reference:**
**Karmen Detector - 57t**
**Shielding - 7000t**

**We can get a few credits:**
**there is 2 m less in concrete slab thickness because the footprint is in the pit**
** ****we can distribute the weight around**

**According to Initial estimations: we can have – 380 t**
**It is preliminarily OK with SNS engineers, however serious structural analysis is required **

**= 6.7 t / m****2**

## Cosmic rays BG estimation

**SNS duty factor  is 4********10****-4**
**This effectively reduce  flux to  10****5**** muons and ~600 neutrons per day entering enclosure**
**We need one meter of steel overburden to reduce hadronic component of atmospheric showers**
**and**
**hermetic veto with efficiency of  99%**
**Our estimations shows that expected number of untagged neutrons events in the detector is a few per day. **
**This is below expected neutrino event rates**
**Extra factor is expected  from PID in detectors****.**

## SNS induced BG

**Most dangerous B.G. is from SNS  neutrons**
**Analysis is complicated because many uncertainties still exist.**
**We know for sure that environment is OK for humans.**
**However neutrinos detectors are much more sensitive then humans!**

## Proton beam tunnel (HETB) cross cut

**Neutrino**
**enclosure**

**Beam**

**3.6 m of steel**

## SNS induced neutron flux

**High energy neutrons**
**can be eliminated using ****time cut**
**To reduce low energy neutrons (neutron gas), ****extra shielding and neutron absorbers are required**
**PID from detectors is welcome **

**This is a very conservative estimations**

## Shielding and detectors mass

**Our initial assessments shows:**
**We need 1 m of  steel shielding on the top**
**And at least 0.5 m from the front the and right sides + some structural from the left and from the back**
**This gives us ~ 340 tons for shielding and 40 tons for detectors.**
**Total 380 tons looks OK, however there is no margin**

**Need very diligent BG simulations, and careful engineering !!!**

## Possible Schedule

**Formal Proposal to DOE - January 2004**
**Detectors R&D and design - 2004 - 2006**
**Detectors Construction - FY 2006 - 2007**
**Shielding Enclosure Erection - 2007**
**Detectors Installation Completed - Spring 2008**
**Detectors Commissioning- Summer 2008**.

## Conclusion

**We have a good opportunity to start a program to use neutrinos from world most powerful intermediate energy neutrino source to collect unique data**
**Nuclear, Astrophysics, and Particles Physics communities need this data**
**Lets do it !!!**