Hi.\nIs it possible to get the total absolute memontum value of a particle at a particular hit/cell (not vector, which I suppose can only be estimated once a track is found to get the direction of the hit) given only the deposited charge(s) that is available in the cells dataset?\nThanks
", "messages": [ { "id": 328537, "postDate": "2018-05-14T15:22:16.927Z", "content": "Questions to physicists and CERN here :)
\n\nProviding you reconstruct the tracks and all, I would suppose after that you try to infer the following:
\n\norigin point (I would assume x,y = 0,0 and z a certain value)
particle momentum at origin point (px0,py0,pz0 are part of the helix equation)
its charge (direction of the helix)
mass (part of helix equation)
particle type ?
Am I wrong ?
\n\nI thought maybe as a second phase of validating predicted tracks, we could try to find these properties after which the total momentum can be estimated at a hit coordinate and then re-run DBSCAN (for instance).
\n\nAs a test, I assumed I have an estimated total momentum (root of sum of squares from truth file). I added it to x,y,z coordinates and re-run HDBSCAN. I got 0.467.
\n\nSo there might be some benefit trying to estimate the momentum...
", "rawMarkdown": "Questions to physicists and CERN here :)\n\nProviding you reconstruct the tracks and all, I would suppose after that you try to infer the following:\n\n- origin point (I would assume x,y = 0,0 and z a certain value)\n\n- particle momentum at origin point (px0,py0,pz0 are part of the helix equation)\n\n- its charge (direction of the helix)\n\n- mass (part of helix equation)\n\n- particle type ?\n\nAm I wrong ?\n\nI thought maybe as a second phase of validating predicted tracks, we could try to find these properties after which the total momentum can be estimated at a hit coordinate and then re-run DBSCAN (for instance).\n\nAs a test, I assumed I have an estimated total momentum (root of sum of squares from truth file). I added it to x,y,z coordinates and re-run HDBSCAN. I got 0.467. \n\nSo there might be some benefit trying to estimate the momentum...", "votes": 1, "replies": [ { "id": 328666, "postDate": "2018-05-14T21:18:20.153Z", "content": "Total momentum is almost conserved, so by attaching the total momentum (from the truth) to x,y,z coordinates, you're essentially tagging all x,y,z hits from the same true particle with the same float. No wonder this improve HDBSCAN !
", "rawMarkdown": "Total momentum is almost conserved, so by attaching the total momentum (from the truth) to x,y,z coordinates, you're essentially tagging all x,y,z hits from the same true particle with the same float. No wonder this improve HDBSCAN ! " }, { "id": 328670, "postDate": "2018-05-14T21:25:19.103Z", "content": "On one can be inferred from the reconstructed helix:\n - origin point : to a certain extent yes, one can chose (x,y) where the track crosses the plane z=0\n - momentum yes (so in total 5 parameters with the origin point)\n - mass : not really (for the same momentum, difficult to separate a low mass high speed particle from a higher mass, lower speed particle)\n - identity : no would need the mass
", "rawMarkdown": "On one can be inferred from the reconstructed helix:\n - origin point : to a certain extent yes, one can chose (x,y) where the track crosses the plane z=0\n - momentum yes (so in total 5 parameters with the origin point)\n - mass : not really (for the same momentum, difficult to separate a low mass high speed particle from a higher mass, lower speed particle)\n - identity : no would need the mass" } ] }, { "id": 328532, "postDate": "2018-05-14T14:57:06.010Z", "content": "Energy loss of ionizing particles is described by Bethe Bloch formula (Source). \nCheck the domain of \"Minimum Ionizing Particles\".
", "rawMarkdown": "Energy loss of ionizing particles is described by Bethe Bloch formula ([Source][1]). \nCheck the domain of \"Minimum Ionizing Particles\".\n\n [1]: http://pdg.lbl.gov/2009/reviews/rpp2009-rev-passage-particles-matter.pdf", "votes": 1 }, { "id": 327989, "postDate": "2018-05-13T04:49:12.233Z", "content": "Hi.\nIs it possible to get the total absolute memontum value of a particle at a particular hit/cell (not vector, which I suppose can only be estimated once a track is found to get the direction of the hit) given only the deposited charge(s) that is available in the cells dataset?\nThanks
", "rawMarkdown": "Hi.\nIs it possible to get the total absolute memontum value of a particle at a particular hit/cell (not vector, which I suppose can only be estimated once a track is found to get the direction of the hit) given only the deposited charge(s) that is available in the cells dataset?\nThanks\n", "votes": 1 }, { "id": 328797, "postDate": "2018-05-15T05:06:44.427Z", "content": "not sure if this is useful, but i am following equations from this site:
\n\nhttp://www-jlc.kek.jp/subg/offl/lib/docs/helix_manip/node3.html
\n\nhttp://www.hep.uniovi.es/TAE2009/presentations/100909-2-ATLAS-SMarti.pdf
", "rawMarkdown": "not sure if this is useful, but i am following equations from this site:\n\nhttp://www-jlc.kek.jp/subg/offl/lib/docs/helix_manip/node3.html\n\nhttp://www.hep.uniovi.es/TAE2009/presentations/100909-2-ATLAS-SMarti.pdf", "votes": 2 }, { "id": 328526, "postDate": "2018-05-14T14:41:45.720Z", "content": "Interesting idea. You can calculate total momentum from the truth data as p = sqrt(px^2 +py^2 +pz^2).\nThis momentum is related to the particle's energy by p^2= E^2/c^2 - m^2c^2
\n\nDunno how this relates to the value in the cells data. Use regression on the dataset and see if you can predict total momentum or total momentum loss from hit-to-hit from \"value\" in cells-data ? Would love to hear the result. Remember some detectors don't report this value, so you need to exlude this data.
", "rawMarkdown": "Interesting idea. You can calculate total momentum from the truth data as p = sqrt(px^2 +py^2 +pz^2).\nThis momentum is related to the particle's energy by p^2= E^2/c^2 - m^2c^2\n\nDunno how this relates to the value in the cells data. Use regression on the dataset and see if you can predict total momentum or total momentum loss from hit-to-hit from \"value\" in cells-data ? Would love to hear the result. Remember some detectors don't report this value, so you need to exlude this data.\n\n", "replies": [ { "id": 328530, "postDate": "2018-05-14T14:52:30.973Z", "content": "Energy deposit in the silicons cells has nothing to do with the relativistic quadratic formula you mention. Additionally we are not aware of the mass of the particles.
", "rawMarkdown": "Energy deposit in the silicons cells has nothing to do with the relativistic quadratic formula you mention. Additionally we are not aware of the _mass_ of the particles. " }, { "id": 328550, "postDate": "2018-05-14T15:46:31.730Z", "rawMarkdown": "", "isDeleted": true }, { "id": 328562, "postDate": "2018-05-14T15:59:43.310Z", "content": "Since the width of the material is not given all I can provide is assumption in order to get an idea , 1 Minimum Ionizing Particle (mip) is ~20500 e~ taken from this source p.3
", "rawMarkdown": "Since the width of the material is not given all I can provide is assumption in order to get an idea , 1 Minimum Ionizing Particle (mip) is ~20500 e~ taken from this [source][1] p.3 \n\n\n\n\n [1]: http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/31/011/31011661.pdf" }, { "id": 328563, "postDate": "2018-05-14T16:03:23.757Z", "content": "Great
", "rawMarkdown": "Great" }, { "id": 328779, "postDate": "2018-05-15T04:14:44.537Z", "content": "For some approximate numbers, a minimum ionizing particle (MIP) will typically lose around 2 MeV / (g/cm^2). Silicon has a density of ~2.3 g/cm^3, so MIPs lose around 4.6 MeV / cm in Si. A typical silicon detector will have a width of a few hundred microns and the energy to create an electron-hole pair is 3.6 eV. Putting all this together, you get something on the order of 50k electron-hole pairs for a particle going perpendicular to the silicon.
", "rawMarkdown": "For some approximate numbers, a minimum ionizing particle (MIP) will typically lose around 2 MeV / (g/cm^2). Silicon has a density of ~2.3 g/cm^3, so MIPs lose around 4.6 MeV / cm in Si. A typical silicon detector will have a width of a few hundred microns and the energy to create an electron-hole pair is 3.6 eV. Putting all this together, you get something on the order of 50k electron-hole pairs for a particle going perpendicular to the silicon.", "votes": 2 } ] }, { "id": 328054, "postDate": "2018-05-13T08:38:31.790Z", "content": "I think that he deposited charges are essentially random, and averages depend on not only momentums but also on masses etc.
", "rawMarkdown": "I think that he deposited charges are essentially random, and averages depend on not only momentums but also on masses etc.", "replies": [ { "id": 328360, "postDate": "2018-05-14T04:18:10.430Z", "content": "What is exactly the deposited charge and in what unit is it?\nI noticed that when I sum charges from cells dataset by hit_id, I get rounded numbers for certain volumes or layers and third or 2 thirds on others (didn't check the whole file though, just sampling).
", "rawMarkdown": "What is exactly the deposited charge and in what unit is it?\nI noticed that when I sum charges from cells dataset by hit_id, I get rounded numbers for certain volumes or layers and third or 2 thirds on others (didn't check the whole file though, just sampling). " }, { "id": 328533, "postDate": "2018-05-14T15:03:09.103Z", "content": "could be energy deposited dE for a particular silicon strip with width dx . Some other times it's measured in ADC counts (proportional to the electrons generated)
", "rawMarkdown": "could be energy deposited _dE_ for a particular silicon strip with width _dx_ . Some other times it's measured in ADC counts (proportional to the electrons generated) " }, { "id": 328544, "postDate": "2018-05-14T15:28:58.410Z", "content": "Thanks agerom. If this is the case, given dE (as a proportion of generated electrons), I should be able to calculate the drop in momentum, am I right ?
", "rawMarkdown": "Thanks agerom. If this is the case, given dE (as a proportion of generated electrons), I should be able to calculate the drop in momentum, am I right ?" }, { "id": 328549, "postDate": "2018-05-14T15:46:16.967Z", "content": "Hi, the drop in momentum is a very small effect, indeed.
", "rawMarkdown": "Hi, the drop in momentum is a very small effect, indeed.", "votes": 1 } ] } ], "comments": [ { "id": 328537, "author_name": "Riad Souissi", "author_url": "", "post_date": "2018-05-14T15:22:16.927000", "content": "Questions to physicists and CERN here :)
\n\nProviding you reconstruct the tracks and all, I would suppose after that you try to infer the following:
\n\norigin point (I would assume x,y = 0,0 and z a certain value)
particle momentum at origin point (px0,py0,pz0 are part of the helix equation)
its charge (direction of the helix)
mass (part of helix equation)
particle type ?
Am I wrong ?
\n\nI thought maybe as a second phase of validating predicted tracks, we could try to find these properties after which the total momentum can be estimated at a hit coordinate and then re-run DBSCAN (for instance).
\n\nAs a test, I assumed I have an estimated total momentum (root of sum of squares from truth file). I added it to x,y,z coordinates and re-run HDBSCAN. I got 0.467.
\n\nSo there might be some benefit trying to estimate the momentum...
", "votes": 1, "replies": [ { "id": 328666, "author_name": "David Rousseau", "author_url": "", "post_date": "2018-05-14T21:18:20.153000", "content": "Total momentum is almost conserved, so by attaching the total momentum (from the truth) to x,y,z coordinates, you're essentially tagging all x,y,z hits from the same true particle with the same float. No wonder this improve HDBSCAN !
", "votes": 0, "replies": [] }, { "id": 328670, "author_name": "David Rousseau", "author_url": "", "post_date": "2018-05-14T21:25:19.103000", "content": "On one can be inferred from the reconstructed helix:\n - origin point : to a certain extent yes, one can chose (x,y) where the track crosses the plane z=0\n - momentum yes (so in total 5 parameters with the origin point)\n - mass : not really (for the same momentum, difficult to separate a low mass high speed particle from a higher mass, lower speed particle)\n - identity : no would need the mass
", "votes": 0, "replies": [] } ] }, { "id": 328532, "author_name": "Art", "author_url": "", "post_date": "2018-05-14T14:57:06.010000", "content": "Energy loss of ionizing particles is described by Bethe Bloch formula (Source). \nCheck the domain of \"Minimum Ionizing Particles\".
", "votes": 1, "replies": [] }, { "id": 328797, "author_name": "hengck23", "author_url": "", "post_date": "2018-05-15T05:06:44.427000", "content": "not sure if this is useful, but i am following equations from this site:
\n\nhttp://www-jlc.kek.jp/subg/offl/lib/docs/helix_manip/node3.html
\n\nhttp://www.hep.uniovi.es/TAE2009/presentations/100909-2-ATLAS-SMarti.pdf
", "votes": 2, "replies": [] }, { "id": 328526, "author_name": "maka", "author_url": "", "post_date": "2018-05-14T14:41:45.720000", "content": "Interesting idea. You can calculate total momentum from the truth data as p = sqrt(px^2 +py^2 +pz^2).\nThis momentum is related to the particle's energy by p^2= E^2/c^2 - m^2c^2
\n\nDunno how this relates to the value in the cells data. Use regression on the dataset and see if you can predict total momentum or total momentum loss from hit-to-hit from \"value\" in cells-data ? Would love to hear the result. Remember some detectors don't report this value, so you need to exlude this data.
", "votes": 0, "replies": [ { "id": 328530, "author_name": "Art", "author_url": "", "post_date": "2018-05-14T14:52:30.973000", "content": "Energy deposit in the silicons cells has nothing to do with the relativistic quadratic formula you mention. Additionally we are not aware of the mass of the particles.
", "votes": 0, "replies": [] }, { "id": 328550, "author_name": "", "author_url": "", "post_date": "2018-05-14T15:46:31.730000", "content": "", "votes": 0, "replies": [] }, { "id": 328562, "author_name": "Art", "author_url": "", "post_date": "2018-05-14T15:59:43.310000", "content": "Since the width of the material is not given all I can provide is assumption in order to get an idea , 1 Minimum Ionizing Particle (mip) is ~20500 e~ taken from this source p.3
", "votes": 0, "replies": [] }, { "id": 328563, "author_name": "maka", "author_url": "", "post_date": "2018-05-14T16:03:23.757000", "content": "Great
", "votes": 0, "replies": [] }, { "id": 328779, "author_name": "MuonNeutrino", "author_url": "", "post_date": "2018-05-15T04:14:44.537000", "content": "For some approximate numbers, a minimum ionizing particle (MIP) will typically lose around 2 MeV / (g/cm^2). Silicon has a density of ~2.3 g/cm^3, so MIPs lose around 4.6 MeV / cm in Si. A typical silicon detector will have a width of a few hundred microns and the energy to create an electron-hole pair is 3.6 eV. Putting all this together, you get something on the order of 50k electron-hole pairs for a particle going perpendicular to the silicon.
", "votes": 2, "replies": [] } ] }, { "id": 328054, "author_name": "Victor", "author_url": "", "post_date": "2018-05-13T08:38:31.790000", "content": "I think that he deposited charges are essentially random, and averages depend on not only momentums but also on masses etc.
", "votes": 0, "replies": [ { "id": 328360, "author_name": "Riad Souissi", "author_url": "", "post_date": "2018-05-14T04:18:10.430000", "content": "What is exactly the deposited charge and in what unit is it?\nI noticed that when I sum charges from cells dataset by hit_id, I get rounded numbers for certain volumes or layers and third or 2 thirds on others (didn't check the whole file though, just sampling).
", "votes": 0, "replies": [] }, { "id": 328533, "author_name": "Art", "author_url": "", "post_date": "2018-05-14T15:03:09.103000", "content": "could be energy deposited dE for a particular silicon strip with width dx . Some other times it's measured in ADC counts (proportional to the electrons generated)
", "votes": 0, "replies": [] }, { "id": 328544, "author_name": "Riad Souissi", "author_url": "", "post_date": "2018-05-14T15:28:58.410000", "content": "Thanks agerom. If this is the case, given dE (as a proportion of generated electrons), I should be able to calculate the drop in momentum, am I right ?
", "votes": 0, "replies": [] }, { "id": 328549, "author_name": "Andreas Salzburger", "author_url": "", "post_date": "2018-05-14T15:46:16.967000", "content": "Hi, the drop in momentum is a very small effect, indeed.
", "votes": 1, "replies": [] } ] } ], "raw_markdown_by_id": { "328537": "Questions to physicists and CERN here :)\n\nProviding you reconstruct the tracks and all, I would suppose after that you try to infer the following:\n\n- origin point (I would assume x,y = 0,0 and z a certain value)\n\n- particle momentum at origin point (px0,py0,pz0 are part of the helix equation)\n\n- its charge (direction of the helix)\n\n- mass (part of helix equation)\n\n- particle type ?\n\nAm I wrong ?\n\nI thought maybe as a second phase of validating predicted tracks, we could try to find these properties after which the total momentum can be estimated at a hit coordinate and then re-run DBSCAN (for instance).\n\nAs a test, I assumed I have an estimated total momentum (root of sum of squares from truth file). I added it to x,y,z coordinates and re-run HDBSCAN. I got 0.467. \n\nSo there might be some benefit trying to estimate the momentum...", "328532": "Energy loss of ionizing particles is described by Bethe Bloch formula ([Source][1]). \nCheck the domain of \"Minimum Ionizing Particles\".\n\n [1]: http://pdg.lbl.gov/2009/reviews/rpp2009-rev-passage-particles-matter.pdf", "327989": "Hi.\nIs it possible to get the total absolute memontum value of a particle at a particular hit/cell (not vector, which I suppose can only be estimated once a track is found to get the direction of the hit) given only the deposited charge(s) that is available in the cells dataset?\nThanks\n", "328797": "not sure if this is useful, but i am following equations from this site:\n\nhttp://www-jlc.kek.jp/subg/offl/lib/docs/helix_manip/node3.html\n\nhttp://www.hep.uniovi.es/TAE2009/presentations/100909-2-ATLAS-SMarti.pdf", "328526": "Interesting idea. You can calculate total momentum from the truth data as p = sqrt(px^2 +py^2 +pz^2).\nThis momentum is related to the particle's energy by p^2= E^2/c^2 - m^2c^2\n\nDunno how this relates to the value in the cells data. Use regression on the dataset and see if you can predict total momentum or total momentum loss from hit-to-hit from \"value\" in cells-data ? Would love to hear the result. Remember some detectors don't report this value, so you need to exlude this data.\n\n", "328054": "I think that he deposited charges are essentially random, and averages depend on not only momentums but also on masses etc." } }