pdf with assignments

• The physics motivation and why it is important
  • Text by Mani is fine for now. Polish later.

Traditionally, underground experiments estimate their neutron backgrounds using extensive simulation normalized to a handful of events in their well-shielded target mass. This leads to large error bars and systematic uncertainties between technologies. A better strategy is to choose a few experiments which are uniquely sensitive to aspects of CMINB and use them to improve the physics and implementation of the simulation package(s) used by all experiments. The current status of these experiments is outlined below.

• Older Results from LSD and LVD: Finalized text: Monica, Vitaly, Prisca In good shape.
• New Results from LVD: Monica, Vitaly, Prisca Finished, except any new results from LVD
• Borexino: Text by Toni with edits by Prisca Needs either new results or allowable details
• Kamland: Who will do this?
• Zeplin II/Boulby: Text mostly by Vitaly K Prisca edited and added parts from Monica
• Edelweiss/LSM: Text mostly by Vitaly Prisca edited. More details may be included if new results.
• SNO: (Andrew) No text yet.
• Soudan (NMM) Text by Melinda pretty much finished, except for a statement of results

The two simulations in general use by the physics community are Geant4 [12–13] and FLUKA [14–15]. Geant4 is a C++ based toolkit of physics processes, geometry constructors and processing methods used to transport charged particles through matter. It is written, maintained, and validated by the Geant4 collaboration, which consists of high-energy physicists, space scientists, medical physicists and software engineers. The origin of FLUKA (FLUktuierendeKAskade) goes back to 1962 in the context of understanding shielding requirements for a new proton accelerator at CERN. FLUKA is an official project supported by CERN and INFN. It is a fully integrated particle physics Monte Carlo simulation package based on micro-physics models which are benchmarked and tuned against experimental data.

[Geant4] S. Agostinelli, et al. (the Geant4 collaboration), Nuclear Instrumentation Methods A 506 (2003) 250; J. Allison, et al. (the Geant4 collaboration), IEEE Transactions on Nuclear Science 53 (2006) 270.

[FLUKA] A. Ferrari, P.R. Sala, A. Fassò, and J. Ranft, FLUKA: a multi-particle transport code, CERN-2005-10 (2005), INFN/TC_05/11, SLAC-R-773; G. Battistoni, et al. The FLUKA code: Description and benchmarking, American Institute of Physics Conference Proceedings 896 (2007) 31.

1. Description of the Groom Parameterization and the parameter choices made by Mei&Hime (Andrew)
2. Summary of measurements made in caverns.⇒ (Chao)
   • partial text by Chao on using some scaling applied to muons vs depthsummary of muon measurement (Chao)
3. Description of the MUSUN program and how it works Prisca combined VK texts and edited
   • above includes uncertainties due to rock density/composition/distribution
4. Comparisons with Groom parameterization vs MUSUN simulations.
   • MUSUN results from Boulby and Gran Sasso and how they improved things(Vitaly)
   • MUSUN vs Groom at Soudan (and Homestake, if we have info) (Angie)
5. Comparison of doing muons thru geant vs MUSUN ⇒ (Chao) Edited Summaryupdate Version 3

update Version 4 update Version 6

1. Intro: Start with general description of secondary processes and what is involved. [AV: I think we should be very specific about the models here, it's not always clear to people how these processes are executed, and it matters since people might have better ideas or at least be aware of deficiencies in the microscopic physics ]
2. Compare and contrast how well the Simulations matched data in the experiments called out in II, identifying the differences and problems. For now, just make sure such details are in II, so we can write a summarizing paragraph here later.
3. Parameterizing Results (Andrew will write a short intro to Mei & Hime methodology)
   • Some text and plots from Variation in Particle Generation with Muon Energy may fit here
4. Status and Outstanding Issues: Explain where sims work well and where they don’t. What fits M&H and what doesn’t.
5. New Advances in Geant and FLUKA.Proposed text by Melinda Updates and comments by Anthony
   • a. Geant4: more neutrons and improved multiplicity (Angie, Soudan Geant4). Muon production of neutrons in scint and lead (Melinda or Anthony) [AV: I think this should be pretty specific about the updates to the models building off of what is in the intro to this section]
   • b. Fluka: What has changed in FLUKA since M&H? Tony
   • c. Comparing Geant4 and FLUKA: In terms of muon-induced neutrons (Anthony, Melinda, Tony). In terms of direct comparison at Homestake (Angie, using Raul's FLUKA files)
   • d. Comparing both to data, referencing experiments from the earlier section (where the experimental limitations are explained and cited in detail)

1. Intro: Describe the geometries of the Ge and LXe and LAr setups and our methodology
   • Ge: Angie
   • LXe: Monica
   • LAr: Chao
2. Table of nuclear recoils, giving a definition of the cuts decided upon
3. Veto strategies and resulting reduction in background
4. Singles cuts, energy deposition, Detector specific issues (LAr v Ge v LXe)
5. Predicted event rates and sensitivity reach

• Intro to general effects of going shallow: Soudan Underground Laboratory is at a depth of 2.0 km.w.e., a factor of 1/2.2 that of Homestake 4850. The total muon flux at Soudan is then a factor of 50 higher. However, the expected neutron flux scaling is lower than a factor of 50 due to the lower average muon energy at Soudan. Convolving the Soudan and Homestake muon energy spectra with the typical multiplicity per muon energy, the neutron flux at Soudan is reduced by a factor of 0.89 (*work in progress* – probably too high) from the raw muon flux scaling. This leaves a factor of 45 total increase.
• Compare Sims to CDMS Soudan full MC (plots from CDMS and Angie)
• Results from the Neutron Multiplicity Meter (Melinda)

• Intro to general effects of going deep, with examples from SNOLAB: For facilities deeper than Homestake, spectral shape varies little, as described above. The overall SNOLAB flux is a factor 1/12 below the Homestake flux. The increase in average muon energy results in a negligible factor of 1.03 (*work in progress*) in expected flux.

• This is a Major Work ! Is David still gong to do this??? David implements a scaling scheme and test it using Chao's files, then scale to Soudan and compare to Angies files
• Use this to discuss advantages of depth and how shallow you can go.

What did we learn about Depth and Uncertainties remaining? List and prioritize needs for the future - what bkgd experiments and sims are needed.