Just a snapshot of the amazing fauna that can be found in "our backyard". There was a playful group of these tiny monkeys at the hotel's garden one afternoon. Awesome!
Friday, August 13, 2010
Wonders of Joao Pessoa
Just a snapshot of the amazing fauna that can be found in "our backyard". There was a playful group of these tiny monkeys at the hotel's garden one afternoon. Awesome!
Halo nuclei
Last afternoon we heard about neutron halos in C nuclei, by Tobias Frederico. I was looking forward to this talk, as one of the projects I have lined up for my postdoc work is measuring radii of weakly bound light neutron rich nuclei (maybe even carbon; should read the proposal again!). The outline was there; the talks would start with explanations of the Thomas Collapse and some Efimov Effect that would somewhat pop up again later. I understood Thomas was working on physics around 1935, but what collapsed then was my interest in the talk! The speaker explained why the Thomas collapse happens, but failed to define or explain what the collapse of a quantum mechanical system is. I think he assumed it was something advanced undergrads would be very familiar with, but it's been too long since I'm one of those creatures.
However, after a few more slides I somewhat caught up with it and constructed a picture in my imagination that looked like this: Frederico constructed a simple model of a core + 2 neutrons using some energies of the system as 'scale parameters' (such thing is coming from Efimov). The parameters are just the binding energy between the two neutrons, or a neutron and the core, or the total binding energy of the system (the 4th one sounded just like being also the binding energy to me). Playing with these you can predict what type of halo nuclei you'll have, which are classified by the Latinamerican music they prefer to dance... tango, zamba (a tongue in cheek nomenclature for the possibility of having bound states between two of the three subsystems of the halo nuclei). With that models he obtained what accounts for a parameterization of the matter radius of the system on the binding energy, so he was quite excited with some of the first results from RIKEN on interaction cross sections. An attempt to compare his predicted binding energy with the known mass of 20C (or was it 19C) didn't go so well, but there were large error bars all over the place: in the end these are ultra neutron rich isotopes we're dealing with!
In conclusion, he'd love to see an experiment in 19C + n scattering and test his theory. We'd all love to see it, a 19C or a neutron target would be pretty cool things ... What about using this indirect 19C(d,p)20C things??
However, after a few more slides I somewhat caught up with it and constructed a picture in my imagination that looked like this: Frederico constructed a simple model of a core + 2 neutrons using some energies of the system as 'scale parameters' (such thing is coming from Efimov). The parameters are just the binding energy between the two neutrons, or a neutron and the core, or the total binding energy of the system (the 4th one sounded just like being also the binding energy to me). Playing with these you can predict what type of halo nuclei you'll have, which are classified by the Latinamerican music they prefer to dance... tango, zamba (a tongue in cheek nomenclature for the possibility of having bound states between two of the three subsystems of the halo nuclei). With that models he obtained what accounts for a parameterization of the matter radius of the system on the binding energy, so he was quite excited with some of the first results from RIKEN on interaction cross sections. An attempt to compare his predicted binding energy with the known mass of 20C (or was it 19C) didn't go so well, but there were large error bars all over the place: in the end these are ultra neutron rich isotopes we're dealing with!
In conclusion, he'd love to see an experiment in 19C + n scattering and test his theory. We'd all love to see it, a 19C or a neutron target would be pretty cool things ... What about using this indirect 19C(d,p)20C things??
Thursday, August 12, 2010
Fusion with rare isotope beams
The talk given by prof. Ernst Rhem was really nice. He is very kind and a good person to work. I'm his fan . : )
Ernst talked about the advantages and problems to use radioactive beams to perform fusion reactions. In his seminar, he aborded some techniques to produce radioactive beams and gave an overview for the future using rare isotope beams.
Ernst talked about the advantages and problems to use radioactive beams to perform fusion reactions. In his seminar, he aborded some techniques to produce radioactive beams and gave an overview for the future using rare isotope beams.
Identification of isomers- A tricky business
Ana Bacerril just gave an informative talk on the latest experimental program at NSCL-MSU aimed at pinning down the structure of isotopes in the 100Sn region. She gave a didactic introduction on nuclear isomerism and I finally understood the three mechanisms underlying this phenomenon (shape, spin-gap and K-isomers). The main highlights were the measurements of the half life of the beta decay of 96Cd, hints on isomer of 98In and new gamma lines for 96Ag. The latter result was compared against shell model calculations performed by B. A. Brown.
Breit Idea
Title: Breit Equation in Nuclear Physics
Victim: Marek Nowakowski
Here comes the experimentalist-on-theorist tough love.
16.03 Marek plans on being paced appropriately, but we’ll see, eh?
16.06 3 eqn. on second slide, including GR notation. Nope. Didn’t make it.
16.07 Shit 6-7 eqn. Ok, buckle in, kiddies. Rough ride ahead. Reaching for Excedrin.
16.08 "Bump-tail" parameter. Mind is wandering. And he hates experimentalists, clearly. What did we do to him? I'm searching my memory....
16.10 An eqn with 24 terms filling the slide. Are you serious? If you didn’t want me to pay attention, just write talk in red on blue or yellow on white, and I’ll get the picture. No need to be passive aggressive about it.
16.11 H atom: consider final size of proton (“one of the smallest known corrections”) To that big equation? Corrections to energy, apparently.
16.14 dE ~2.396E-9 eV for binding energy. Why do we care then??? So small!!
16.14 Confirms my assessment- sooooooo small. HOWEVER, QED corrections to recoil on order of E-9. Readiative recoil correction is E-11. Three loops E-15. Holy cow.
16.15 Hyperfine splitting 1S hyperfine frequency—precise enough to see correction due to finite size of proton… quoted as -37.7 kHz
16.16 Hardonic atoms”capture of ...” whoah- slide is gone. Will have to catch it on the wiki.
16.18 Electromagnetic binding of atoms corrections from strong int (shifts energy levels). Look- if you say "atoms" you imply that you are talking about the electrons, not the nucleons.
16.25 In summary, talked about nuclear finite-size effects arising due to electromagnetic form factors.
Ernesto asks about that article that was recently published in which the size of the proton was measured 4% off from expectations—Marek says they need a correction term. There is no time to clarify whether this is a matter of interpretting their data to extract the radius or if there was an issue elsewhere.
Victim: Marek Nowakowski
Here comes the experimentalist-on-theorist tough love.
16.03 Marek plans on being paced appropriately, but we’ll see, eh?
16.06 3 eqn. on second slide, including GR notation. Nope. Didn’t make it.
16.07 Shit 6-7 eqn. Ok, buckle in, kiddies. Rough ride ahead. Reaching for Excedrin.
16.08 "Bump-tail" parameter. Mind is wandering. And he hates experimentalists, clearly. What did we do to him? I'm searching my memory....
16.10 An eqn with 24 terms filling the slide. Are you serious? If you didn’t want me to pay attention, just write talk in red on blue or yellow on white, and I’ll get the picture. No need to be passive aggressive about it.
16.11 H atom: consider final size of proton (“one of the smallest known corrections”) To that big equation? Corrections to energy, apparently.
16.14 dE ~2.396E-9 eV for binding energy. Why do we care then??? So small!!
16.14 Confirms my assessment- sooooooo small. HOWEVER, QED corrections to recoil on order of E-9. Readiative recoil correction is E-11. Three loops E-15. Holy cow.
16.15 Hyperfine splitting 1S hyperfine frequency—precise enough to see correction due to finite size of proton… quoted as -37.7 kHz
16.16 Hardonic atoms”capture of ...” whoah- slide is gone. Will have to catch it on the wiki.
16.18 Electromagnetic binding of atoms corrections from strong int (shifts energy levels). Look- if you say "atoms" you imply that you are talking about the electrons, not the nucleons.
16.25 In summary, talked about nuclear finite-size effects arising due to electromagnetic form factors.
Ernesto asks about that article that was recently published in which the size of the proton was measured 4% off from expectations—Marek says they need a correction term. There is no time to clarify whether this is a matter of interpretting their data to extract the radius or if there was an issue elsewhere.
Good Will Newton
Any relation, Will? To Newton?
Title: Towards a Better Understanding of Nuclear Matter: Synthesizing Neutron Star Observations and Nuclear Experiment
10.00 Choco- bacon. Seems to be for shock effect. Didn’t have breakfast this morning, so it has a slightly different effect on your blogger.
10.01 Blaming Google for his representation of nuclear physicists. Crowd appreciates the friendly start to the talk. A little chit chat is nice before… you know. Take note, kids.
10.02 Arrows everywhere. Interdependence between subfields. We get it. It takes a village.
10.02 J0737-3039 Double pulsar, A & B. Looks like my flight number. 22.7 ms and 2.77 s rotational periods for the two pulsars, respectively. Opposites attract, I guess.
10.03 Did someone say--- muuuurder?? My idea of using crime as a metaphor for nuclear physics is being carried to fruition here. I was thinking more along the lines of a mafia syndicate ande cooked books to describe the discrepencies between the Hamiltonians we construct and what Nature uses.
10.06 e-capture is Will's fall guy for pulsar B formation, and crime of double homicide. There is no statute of limitations here. He is going to lay out the case and take it to the jury. Who killed Pulsar B??
10.10 Wrapping up SNe feature list.
10.13 Distinguishing the rest mass and measured mass of pulsar, which is going to include gravitational binding energy of star. EOS is relevant. M_0/R is relevant here.
10.15 Aw- I really don’t feel like listening to EOS crap. Shouldn’t do that to people before noon, Will. Ya- I’m talking to you, man. EOS slides are ALWAYS boring. It is the only thing worse than spectroscopic factors.
10.16 Isospin asymmetries are “alpha.” Should be nice and confusing.
10.18 Symmetry energy discussed, with list of recent studies.
10.21 Zero minutes left warning is interpreted by Will as ~ 5 minutes left. Common approximation for theorists and crazies. (He's a theorist.) Will made the mistake of assuming the session chair was giving other warnings, too. Ahem.
10.24 Constraints are zeroing in on symmetry energy and mass….
10.26 “…final note,….”
10.27 Questions: tolerance for fallback? Simulations of the SNe explosion give E-3 M_solar if any at all. Will recommends seasoning his slides with salt. You should take most of what he says with a grain of salt: he's Brittish. Hendrik: wouldn’t we expect this to happen more frequently given how common e-capture SNe are? Zach: difference in frequencies for A and B…? Spin up of one from L transfer from the other. (Zach is a shoo-in for the student with the most zeal for asking questions. It is a cry for help- just not the kind you think.)
Title: Towards a Better Understanding of Nuclear Matter: Synthesizing Neutron Star Observations and Nuclear Experiment
10.00 Choco- bacon. Seems to be for shock effect. Didn’t have breakfast this morning, so it has a slightly different effect on your blogger.
10.01 Blaming Google for his representation of nuclear physicists. Crowd appreciates the friendly start to the talk. A little chit chat is nice before… you know. Take note, kids.
10.02 Arrows everywhere. Interdependence between subfields. We get it. It takes a village.
10.02 J0737-3039 Double pulsar, A & B. Looks like my flight number. 22.7 ms and 2.77 s rotational periods for the two pulsars, respectively. Opposites attract, I guess.
10.03 Did someone say--- muuuurder?? My idea of using crime as a metaphor for nuclear physics is being carried to fruition here. I was thinking more along the lines of a mafia syndicate ande cooked books to describe the discrepencies between the Hamiltonians we construct and what Nature uses.
10.06 e-capture is Will's fall guy for pulsar B formation, and crime of double homicide. There is no statute of limitations here. He is going to lay out the case and take it to the jury. Who killed Pulsar B??
10.10 Wrapping up SNe feature list.
10.13 Distinguishing the rest mass and measured mass of pulsar, which is going to include gravitational binding energy of star. EOS is relevant. M_0/R is relevant here.
10.15 Aw- I really don’t feel like listening to EOS crap. Shouldn’t do that to people before noon, Will. Ya- I’m talking to you, man. EOS slides are ALWAYS boring. It is the only thing worse than spectroscopic factors.
10.16 Isospin asymmetries are “alpha.” Should be nice and confusing.
10.18 Symmetry energy discussed, with list of recent studies.
10.21 Zero minutes left warning is interpreted by Will as ~ 5 minutes left. Common approximation for theorists and crazies. (He's a theorist.) Will made the mistake of assuming the session chair was giving other warnings, too. Ahem.
10.24 Constraints are zeroing in on symmetry energy and mass….
10.26 “…final note,….”
10.27 Questions: tolerance for fallback? Simulations of the SNe explosion give E-3 M_solar if any at all. Will recommends seasoning his slides with salt. You should take most of what he says with a grain of salt: he's Brittish. Hendrik: wouldn’t we expect this to happen more frequently given how common e-capture SNe are? Zach: difference in frequencies for A and B…? Spin up of one from L transfer from the other. (Zach is a shoo-in for the student with the most zeal for asking questions. It is a cry for help- just not the kind you think.)
Dark Blog
First up today, the final Thursday of the conference, is Pedro Alevino with "Dark matter and dark energy: a review and prospects"
9.05 He is not a nuclear physicist - he's a cosmologist.
9.11 Hubble expansion implies an age of the universe of 14Gyr. Completely wrong of course - Genesis tells us it's only around 6,000 yrs old. I've seen the dinosaur footprints next to the human footprints.
9.13 Need an accelerating universe to give an age of universe greater than 10Gyr. This is puzzling to me - from my cosmology course I distinctly remembering solving the Friedmann-Robertson-Walker equations and getting a universe age of 13Gyr without any dark energy. Hmmmm...
9.14 And now the FRW equations and EoS of the universe are flashed up. We're introduced to omegas:
Omega_m - density of matter/critical density of matter
Omega_e - density of dark energy/critical density of matter
9.16 Critical density: smaller - expand forever, greater - collapses at some point. This is without dark energy.
9.17 Dark energy has already been assumed to exist. Evidence to follow...
9.20 Primordial nucleosynthesis, when T < 0.1MeV. From nucleosynthesis, we can derive that 5% of matter density of universe is baryonic.
9.24 Cosmic Microwave Background is shown. Most perfect black body spectrum known. Not totally perfect though, there are observed temperature fluctuations due to density fluctuations in the plasma of the early universe.
9.25 Size of fluctuations consistent with flat universe.
9.26 These fluctuations are responsible for large scale structure formation - we can see their echo in the distribution of galaxies.
9.27 I get the feeling that the speaker is going for a shock and awe approach to the talk. Cosmologists do simulations with more particles than there are people on Earth!
9.29 Here comes the Type Ia SN evidence. He skips over the fact that the data appears consistent with no dark energy as well as dark energy.
9.31 Dark matter! Evidence: rotation curves of galaxies. He mentions changing gravity, but this doesn't work in explaining galaxy cluster collisions (e.g. the Bullet cluster). I have been to talks by Modified Gravity people claiming that it can.
9.36 The next slide loses me, partly because I missed the definition of the 'w' parameter which tells us about the dark energy EoS. 9.37 More long equations. Shock and awe.
9.38 Not natural to have w = constant, apparently. Indeed, it's illegal in 13 states in the US.
9.39 What the ?&$%? I wouldn't want to look at that slide on hallucenogenics. I'm stuggling with just coffee.
9.40 I have absolutely no idea what these domain wall networks are. But they can provide dark energy.
9.41 Relativistic and non-relativistic colored splotches are shown. They both look the same. Nevertheless one is ruled out.
9.42 Unified dark matter and dark energy! What are we going to call this unholy union?
9.45 The Planck satellite is going to constrain some of this stuff by measuring the CMB to unprecedented accuracy.
9.46 Summary: everything is known, except for what is dark matter and dark energy?
9.47 I'm waiting for the promised connection to nuclear physics in any useful way for this audience.
9.50 Questions. Modifying gravity is asked about. Its is more complicated, but it can be made to explain observations - this is a little different to what was said earlier.
9.52 Carlos asks about the black hole contribution to dark matter. The black hole mas in the universe is rather uncertain.
9.54 Some English dude asks about the Type Ia supernovae data - that the data, by eye, appears to be consistent with no-dark energy as well as dark energy. He agrees, but statistically, when combined with other data, it favors dark energy. So its no good on its own, apparently.
9.56 Unbelievable - the same English dude has sneaked a second question in. He asks about the reason for the historical preference for dark matter rather than MOND. Why has, overwhelmingly, so much more effort has been devoted to dark matter than modifying gravity? Is it philosophical? The answer refers to modern evidence, which rather misses the point.
9.58 The English guy has finally shut up, and the talk ends.
9.05 He is not a nuclear physicist - he's a cosmologist.
9.06 The beginning of dark energy: Einstein's famous 'greatest mistake'- the cosmological constant introduced into his gravitational field equations to give a static universe. By doing this he missed the opportunity to theoretically predict the expanding universe discovered by Hubble in 1929 from redshifted spectral lines from galaxies. Einstein really was a bit dim, wasn't he?
9.11 Hubble expansion implies an age of the universe of 14Gyr. Completely wrong of course - Genesis tells us it's only around 6,000 yrs old. I've seen the dinosaur footprints next to the human footprints.
9.13 Need an accelerating universe to give an age of universe greater than 10Gyr. This is puzzling to me - from my cosmology course I distinctly remembering solving the Friedmann-Robertson-Walker equations and getting a universe age of 13Gyr without any dark energy. Hmmmm...
9.14 And now the FRW equations and EoS of the universe are flashed up. We're introduced to omegas:
Omega_m - density of matter/critical density of matter
Omega_e - density of dark energy/critical density of matter
9.16 Critical density: smaller - expand forever, greater - collapses at some point. This is without dark energy.
9.17 Dark energy has already been assumed to exist. Evidence to follow...
9.20 Primordial nucleosynthesis, when T < 0.1MeV. From nucleosynthesis, we can derive that 5% of matter density of universe is baryonic.
9.24 Cosmic Microwave Background is shown. Most perfect black body spectrum known. Not totally perfect though, there are observed temperature fluctuations due to density fluctuations in the plasma of the early universe.
9.25 Size of fluctuations consistent with flat universe.
9.26 These fluctuations are responsible for large scale structure formation - we can see their echo in the distribution of galaxies.
9.27 I get the feeling that the speaker is going for a shock and awe approach to the talk. Cosmologists do simulations with more particles than there are people on Earth!
9.29 Here comes the Type Ia SN evidence. He skips over the fact that the data appears consistent with no dark energy as well as dark energy.
9.31 Dark matter! Evidence: rotation curves of galaxies. He mentions changing gravity, but this doesn't work in explaining galaxy cluster collisions (e.g. the Bullet cluster). I have been to talks by Modified Gravity people claiming that it can.
9.36 The next slide loses me, partly because I missed the definition of the 'w' parameter which tells us about the dark energy EoS. 9.37 More long equations. Shock and awe.
9.38 Not natural to have w = constant, apparently. Indeed, it's illegal in 13 states in the US.
9.39 What the ?&$%? I wouldn't want to look at that slide on hallucenogenics. I'm stuggling with just coffee.
9.40 I have absolutely no idea what these domain wall networks are. But they can provide dark energy.
9.41 Relativistic and non-relativistic colored splotches are shown. They both look the same. Nevertheless one is ruled out.
9.42 Unified dark matter and dark energy! What are we going to call this unholy union?
9.45 The Planck satellite is going to constrain some of this stuff by measuring the CMB to unprecedented accuracy.
9.46 Summary: everything is known, except for what is dark matter and dark energy?
9.47 I'm waiting for the promised connection to nuclear physics in any useful way for this audience.
9.50 Questions. Modifying gravity is asked about. Its is more complicated, but it can be made to explain observations - this is a little different to what was said earlier.
9.52 Carlos asks about the black hole contribution to dark matter. The black hole mas in the universe is rather uncertain.
9.54 Some English dude asks about the Type Ia supernovae data - that the data, by eye, appears to be consistent with no-dark energy as well as dark energy. He agrees, but statistically, when combined with other data, it favors dark energy. So its no good on its own, apparently.
9.56 Unbelievable - the same English dude has sneaked a second question in. He asks about the reason for the historical preference for dark matter rather than MOND. Why has, overwhelmingly, so much more effort has been devoted to dark matter than modifying gravity? Is it philosophical? The answer refers to modern evidence, which rather misses the point.
9.58 The English guy has finally shut up, and the talk ends.
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