Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Weakly-interacting massive particles wikipedia , lookup
Electron scattering wikipedia , lookup
ALICE experiment wikipedia , lookup
Eigenstate thermalization hypothesis wikipedia , lookup
Theoretical and experimental justification for the Schrödinger equation wikipedia , lookup
Searching for Lightly Ionizing Particles Searches for Lightly Ionizing Particles The low energy threshold allows us to search for energetic Lightly Ionizing Particles (LIPs) produced by cosmogenic processes. Opportunity: no prior search for e/q < 6! MACRO 2006 MACRO Collaboration (arXiv:hep-ex/042006) Perl, Lee, and Loomba, Annu. Rev. Nucl. Part. Sci. 59, 47 (2009). Searches for Lightly Ionizing Particles The low energy threshold allows us to search for energetic Lightly Ionizing Particles (LIPs) produced by cosmogenic processes. Opportunity: no prior search for e/q < 6! 7.6 cm LIP Search Livetimes: T2: 59.6 days T4: 142.4 days LIP Topology Requirement Hits all Detectors! •Relativistic, Energetic, Hits all Detectors! • Only 1 Tower Hit Relativistic, Hits all Detectors – in STRAIGHT LINE LIPs SIGNAL Only 1 Tower Hit Avoids Shower LIPs SIGNAL NOT signal NOT Signal LIP Topology: Background Reduction The topology requirement decreases the Compton background by about a factor of 105. Tower 2 Tower 4 Track Linearity and Energy Consistency Hitsallall Detectors in STRAIGHT •Relativistic, Relativistic, Hits Detectors – in–STRAIGHT LINE LINE • Deposit Similar Energy LIPs SIGNAL Plus, Basic criteria: Detector OK Signal >> Noise NOT Signal Expected LIP Energy Depositions The energy-deposition probability is given by: Where mc is the average number of collision, fn(E,v) is the nfold convolution of the single interaction spectrum, and E is the energy deposited by a charged particle with velocity v. Using Photo-Absorption-Ionization (PAI) model A method to improve tracking and particle identification in TPCs and silicon detectors Hans Bichsel (Nuclear Instruments and Methods in Physics Research A 562 (2006) 154–197). Expected LIP Energy Depositions The energy-deposition probability is then: The idea: look for energy depositions consistent with a LIP with a given fractional charge, f. Repeat for the next fractional charge, etc. Energy Consistency LIPs energy deposition in detectors INDEPENDENT DF1 DF0 Define an energy consistency criteria, Ec, that compares the expected “distance” in cumulative probability vs that measured: Energy Consistency DF1 = 0 LIPs energy deposition in detectors INDEPENDENT DF1 DF0 Define an energy consistency criteria, Ec, that compares the expected “distance” in cumulative probability vs that measured: Track Linearity Require the reconstructed event positions to be consistent with a linear track. LIPs pass straight, Backgrounds not! Estimate xy-position resolution using events with interactions on adjacent detectors. Neighboring Surface events 2 fit to tracks. Perform c provide detector-resolution Fit LIP Track Neighboring Surface Events Y-location (mm) Fit Compton Track X-location (mm) Combined LIP Background Rejection Tower 4: f = 1/15 Combined CDMSII LIP Results Tower 4: f = 1/15 No candidates observed, so we set a limit. LIP Limits CDMS Collaboration (arXiv:1409.3270) No candidates observed, so we set a limit. Future LIP Searches - Strategy Ways to improve upon the CDMSII LIP Search LIPs energy deposition in detectors INDEPENDENT • Increase the exposure (more towers, run longer) • Improved detection efficiency for LIPs with small fractional charges CDMSII An ultra-low threshold A thicker detector LIP Mass (eV) - LIP Fractional Charge, f LIP Search – Threshold is Key To get a feel for how small a value of f, we can probe, let’s consider LIPs energyenergy deposition in detectors INDEPENDENT the expected probability deposition distribution. CDMSII 2.5keV threshold Note: I assumed a 3.3cm LIP path length in germanium. LIP Search – Threshold is Key To get a feel for how small a value of f, we can probe, let’s consider LIPs energyenergy deposition in detectors INDEPENDENT the expected probability deposition distribution. 100eV threshold Note: I assumed a 3.3cm LIP path length in germanium. LIP Search – Threshold is Key To get a feel for how small a value of f, we can probe, let’s consider LIPs energyenergy deposition in detectors INDEPENDENT the expected probability deposition distribution. 10eV threshold Note: I assumed a 3.3cm LIP path length in germanium. MINER LIP PDFs • The expected energy depositions in Ge/Si are similar. LIPs energyenables deposition in detectors INDEPENDENT • Difference cross-checking of any potential signal. MINER Strategy Tower 4: f = 1/15 Energy Consistency powerful. More detectors = more power. Tracking less powerful and harder. MINER LIP Discovery Potential Sensitivity to MUCH smaller fractional charges! LIPs energy deposition in detectors INDEPENDENT State livetime assumed. MINER LIP Discovery Potential LIP Fractional Charge, f CDMSII MINER LIP Mass (eV) LIPs energy deposition in detectors INDEPENDENT