I stumbled onto a great resource for understanding the Muon detection system at http://iopscience.iop.org/1748-0221/3/08/S08005/pdf/1748-0221_3_08_S08005.pdf, starting page 125.
\n\nQuestion:
\n\nwithin the test.csv data set of runs, the variables for detected muons are:
\n\nThe data seems to only tell you direction in 2 dimensions, ie. total momentum and transverse momentum. Is there a way to tell the direction of the muon in 3 dimensions and track it back to where it was created?
\n\nPerhaps I have missed something important here.
\n\nThank you, any ideas or comments welcome.
\n\nMuon detection from the article:
\n\n\n", "messages": [ { "id": "88117", "postDate": "08/03/2015 17:21:33", "content": "6.3 Muon System
\n \nMuon triggering and offline muon identification are fundamental\n requirements of the LHCb experiment. Muons are present in the final\n states of many CP-sensitive B decays, in particular the two\n gold-plated decays, B0 d → J/ψ (µ\n +µ −)K 0 S and B0 s → J/ψ (µ\n +µ −)φ [2]. They play a major role in CP asymmetry and oscillation measurements, since muons from semi-leptonic b decays provide a tag of\n the initial state flavor of the accompanying neutral B mesons. In\n addition, the study of rare B decays such as the flavour-changing\n neutral current decay, B0 s → µ\n +µ −, may reveal new physics beyond the Standard Model [163].
\n \nThe muon system provides fast information for the high-pT muon trigger\n at the earliest level (Level-0) and muon identification for the\n high-level trigger (HLT) and offline analysis.
\n
I stumbled onto a great resource for understanding the Muon detection system at http://iopscience.iop.org/1748-0221/3/08/S08005/pdf/1748-0221_3_08_S08005.pdf, starting page 125.
\n\nQuestion:
\n\nwithin the test.csv data set of runs, the variables for detected muons are:
\n\nThe data seems to only tell you direction in 2 dimensions, ie. total momentum and transverse momentum. Is there a way to tell the direction of the muon in 3 dimensions and track it back to where it was created?
\n\nPerhaps I have missed something important here.
\n\nThank you, any ideas or comments welcome.
\n\nMuon detection from the article:
\n\n\n", "rawMarkdown": "I stumbled onto a great resource for understanding the Muon detection system at [http://iopscience.iop.org/1748-0221/3/08/S08005/pdf/1748-0221_3_08_S08005.pdf][1], starting page 125.\r\n\r\nQuestion: \r\n\r\nwithin the test.csv data set of runs, the variables for detected muons are:\r\n\r\n - p0_pt - Transverse momentum of p0 muon.\r\n - p0_p - Momentum of p0 muon.\r\n - p0_eta - Pseudorapidity of p0 muon.\r\n - p0_IP - Impact parameter of p0 muon.\r\n - p0_IPSig - Impact Parameter Significance of p0 muon.\r\n\r\nThe data seems to only tell you direction in 2 dimensions, ie. total momentum and transverse momentum. Is there a way to tell the direction of the muon in 3 dimensions and track it back to where it was created?\r\n\r\nPerhaps I have missed something important here.\r\n\r\nThank you, any ideas or comments welcome.\r\n\r\nMuon detection from the article:\r\n\r\n> **6.3 Muon System**\r\n> \r\n> Muon triggering and offline muon identification are fundamental\r\n> requirements of the LHCb experiment. Muons are present in the final\r\n> states of many CP-sensitive B decays, in particular the two\r\n> gold-plated decays, B0 d → J/ψ (µ\r\n> +µ −)K 0 S and B0 s → J/ψ (µ\r\n> +µ −)φ [2]. They play a major role in CP asymmetry and oscillation measurements, since muons from semi-leptonic b decays provide a tag of\r\n> the initial state flavor of the accompanying neutral B mesons. In\r\n> addition, the study of rare B decays such as the flavour-changing\r\n> neutral current decay, B0 s → µ\r\n> +µ −, may reveal new physics beyond the Standard Model [163].\r\n> \r\n> The muon system provides fast information for the high-pT muon trigger\r\n> at the earliest level (Level-0) and muon identification for the\r\n> high-level trigger (HLT) and offline analysis.\r\n\r\n\r\n [1]: http://iopscience.iop.org/1748-0221/3/08/S08005/pdf/1748-0221_3_08_S08005.pdf", "votes": null }, { "id": "88370", "postDate": "08/04/2015 14:14:32", "content": "6.3 Muon System
\n \nMuon triggering and offline muon identification are fundamental\n requirements of the LHCb experiment. Muons are present in the final\n states of many CP-sensitive B decays, in particular the two\n gold-plated decays, B0 d → J/ψ (µ\n +µ −)K 0 S and B0 s → J/ψ (µ\n +µ −)φ [2]. They play a major role in CP asymmetry and oscillation measurements, since muons from semi-leptonic b decays provide a tag of\n the initial state flavor of the accompanying neutral B mesons. In\n addition, the study of rare B decays such as the flavour-changing\n neutral current decay, B0 s → µ\n +µ −, may reveal new physics beyond the Standard Model [163].
\n \nThe muon system provides fast information for the high-pT muon trigger\n at the earliest level (Level-0) and muon identification for the\n high-level trigger (HLT) and offline analysis.
\n
The variables p, pt and eta are related by the following formula: p = pt*cosh(eta), and eta is related to the polar angle theta by eta = -ln(tan(theta/2)). Information to extract the azimuthal angle phi (which would be very useful) appears to be missing from the data (I'm not aware of a way to infer it from the information that is present). This information is needed to determine the 3D trajectory of the muon. Look here:\nhttps://en.wikipedia.org/wiki/Pseudorapidity
", "rawMarkdown": "The variables p, pt and eta are related by the following formula: p = pt*cosh(eta), and eta is related to the polar angle theta by eta = -ln(tan(theta/2)). Information to extract the azimuthal angle phi (which would be very useful) appears to be missing from the data (I'm not aware of a way to infer it from the information that is present). This information is needed to determine the 3D trajectory of the muon. Look here:\r\nhttps://en.wikipedia.org/wiki/Pseudorapidity", "votes": null }, { "id": "88394", "postDate": "08/04/2015 16:03:07", "content": "Thanks, I agree. There are also the 3 variables:
\n\nUnfortunately there is no unit for the variable (ie. are they 10^-6 meters or 10^-15 meters??). These variables don't seem to make any sense since they have a fairly even distribution (although biased to the high side). I would have expected them to be either 0 (the two muons were created at the same time and place) or non-0 (one muon was created then a second one created a little ways away in time and space from the by-product of the first muon creation event).
\n\nCan anyone add to the understanding, maybe the admins? Are these real variables or only tossed into the mix as noise?
", "rawMarkdown": "Thanks, I agree. There are also the 3 variables:\r\n\r\n - DOCAone - Distance of Closest Approach between p0 and p1.\r\n - DOCAtwo - Distance of Closest Approach between p1 and p2.\r\n - DOCAthree - Distance of Closest Approach between p0 and p2.\r\n\r\nUnfortunately there is no unit for the variable (ie. are they 10^-6 meters or 10^-15 meters??). These variables don't seem to make any sense since they have a fairly even distribution (although biased to the high side). I would have expected them to be either 0 (the two muons were created at the same time and place) or non-0 (one muon was created then a second one created a little ways away in time and space from the by-product of the first muon creation event).\r\n\r\nCan anyone add to the understanding, maybe the admins? Are these real variables or only tossed into the mix as noise?", "votes": null }, { "id": "88703", "postDate": "08/06/2015 18:48:02", "content": "The DOCAs are reconstructed quantities, so the true value is smeared out by the detector resolution. These are real variables ;)
\n\nCheers,\nMarcin
", "rawMarkdown": "The DOCAs are reconstructed quantities, so the true value is smeared out by the detector resolution. These are real variables ;)\r\n\r\nCheers,\r\nMarcin", "votes": null } ], "comments": [ { "id": 88370, "author_name": "andrewjohnlowe", "author_url": "", "post_date": "08/04/2015 14:14:32", "content": "The variables p, pt and eta are related by the following formula: p = pt*cosh(eta), and eta is related to the polar angle theta by eta = -ln(tan(theta/2)). Information to extract the azimuthal angle phi (which would be very useful) appears to be missing from the data (I'm not aware of a way to infer it from the information that is present). This information is needed to determine the 3D trajectory of the muon. Look here:\nhttps://en.wikipedia.org/wiki/Pseudorapidity
", "votes": null, "replies": [] }, { "id": 88394, "author_name": "edguy99", "author_url": "", "post_date": "08/04/2015 16:03:07", "content": "Thanks, I agree. There are also the 3 variables:
\n\nUnfortunately there is no unit for the variable (ie. are they 10^-6 meters or 10^-15 meters??). These variables don't seem to make any sense since they have a fairly even distribution (although biased to the high side). I would have expected them to be either 0 (the two muons were created at the same time and place) or non-0 (one muon was created then a second one created a little ways away in time and space from the by-product of the first muon creation event).
\n\nCan anyone add to the understanding, maybe the admins? Are these real variables or only tossed into the mix as noise?
", "votes": null, "replies": [] }, { "id": 88703, "author_name": "albercik1905", "author_url": "", "post_date": "08/06/2015 18:48:02", "content": "The DOCAs are reconstructed quantities, so the true value is smeared out by the detector resolution. These are real variables ;)
\n\nCheers,\nMarcin
", "votes": null, "replies": [] } ], "raw_markdown_by_id": { "88117": "I stumbled onto a great resource for understanding the Muon detection system at [http://iopscience.iop.org/1748-0221/3/08/S08005/pdf/1748-0221_3_08_S08005.pdf][1], starting page 125.\r\n\r\nQuestion: \r\n\r\nwithin the test.csv data set of runs, the variables for detected muons are:\r\n\r\n - p0_pt - Transverse momentum of p0 muon.\r\n - p0_p - Momentum of p0 muon.\r\n - p0_eta - Pseudorapidity of p0 muon.\r\n - p0_IP - Impact parameter of p0 muon.\r\n - p0_IPSig - Impact Parameter Significance of p0 muon.\r\n\r\nThe data seems to only tell you direction in 2 dimensions, ie. total momentum and transverse momentum. Is there a way to tell the direction of the muon in 3 dimensions and track it back to where it was created?\r\n\r\nPerhaps I have missed something important here.\r\n\r\nThank you, any ideas or comments welcome.\r\n\r\nMuon detection from the article:\r\n\r\n> **6.3 Muon System**\r\n> \r\n> Muon triggering and offline muon identification are fundamental\r\n> requirements of the LHCb experiment. Muons are present in the final\r\n> states of many CP-sensitive B decays, in particular the two\r\n> gold-plated decays, B0 d → J/ψ (µ\r\n> +µ −)K 0 S and B0 s → J/ψ (µ\r\n> +µ −)φ [2]. They play a major role in CP asymmetry and oscillation measurements, since muons from semi-leptonic b decays provide a tag of\r\n> the initial state flavor of the accompanying neutral B mesons. In\r\n> addition, the study of rare B decays such as the flavour-changing\r\n> neutral current decay, B0 s → µ\r\n> +µ −, may reveal new physics beyond the Standard Model [163].\r\n> \r\n> The muon system provides fast information for the high-pT muon trigger\r\n> at the earliest level (Level-0) and muon identification for the\r\n> high-level trigger (HLT) and offline analysis.\r\n\r\n\r\n [1]: http://iopscience.iop.org/1748-0221/3/08/S08005/pdf/1748-0221_3_08_S08005.pdf", "88370": "The variables p, pt and eta are related by the following formula: p = pt*cosh(eta), and eta is related to the polar angle theta by eta = -ln(tan(theta/2)). Information to extract the azimuthal angle phi (which would be very useful) appears to be missing from the data (I'm not aware of a way to infer it from the information that is present). This information is needed to determine the 3D trajectory of the muon. Look here:\r\nhttps://en.wikipedia.org/wiki/Pseudorapidity", "88394": "Thanks, I agree. There are also the 3 variables:\r\n\r\n - DOCAone - Distance of Closest Approach between p0 and p1.\r\n - DOCAtwo - Distance of Closest Approach between p1 and p2.\r\n - DOCAthree - Distance of Closest Approach between p0 and p2.\r\n\r\nUnfortunately there is no unit for the variable (ie. are they 10^-6 meters or 10^-15 meters??). These variables don't seem to make any sense since they have a fairly even distribution (although biased to the high side). I would have expected them to be either 0 (the two muons were created at the same time and place) or non-0 (one muon was created then a second one created a little ways away in time and space from the by-product of the first muon creation event).\r\n\r\nCan anyone add to the understanding, maybe the admins? Are these real variables or only tossed into the mix as noise?", "88703": "The DOCAs are reconstructed quantities, so the true value is smeared out by the detector resolution. These are real variables ;)\r\n\r\nCheers,\r\nMarcin" }, "source": "meta" }